.::: Cystic Masses of the Spleen: Radiologic- - RadioGraphics

.::: Cystic Masses of the 

Ri:::: Spleen: Radiologic- 

‘:: Pathologic Correlation1 

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Maribel Urrutia, MD 

Patricia j Mergo, MD 

Luis H. Ros, MD 

Gladys M Torres, MD 

Pablo R. Ros, MD 

Many focal splenic lesions may appear to be cystic at cross-sectional imaging. 

In this article, the following types of cystic splenic masses are discussed: 

congenital (true cyst), inflammatory (abscesses, hydatid cyst), 

vascular (infarction, peliosis), posttraumatic (hematoma, false cyst), and 

neoplastic (hemangioma, lymphangioma, lymphoma, metastasis). The 

key fmdings at ultrasound, computed tomography, and magnetic reso- 

nance imaging can be correlated with underlying gross and microscopic 

pathologic findings. Although tissue sampling is still required in many 

cases to yield a definitive diagnosis, recognition and understanding of 

the spectrum of imaging and pathologic features of these lesions often 

help narrow the differential diagnosis. 

U INTRODUCTION 

Cystic masses do not commonly occur in the spleen. However, in addition to “splenic 

cysts” (either true epidermoid or false posttraumatic cysts), there is a spectrum of le- 

sions that have a predominantly cystic appearance at imaging. Cystic splenic masses 

may be congenital, inflammatory, vascular, posttraumatic, or neoplastic. 

An understanding of the underlying pathologic changes in each entity aids the radiologist 

in evaluating these splenic lesions. We review a range of cystic splenic lesions 

to heighten the radiologist’s awareness of these lesions. In addition, we present a classi- 

fication of these masses based on their pathologic features (Table 1). Each entity is dis- 

cussed, with a definition and a summary of the key microscopic and gross fmdings that 

determine its imaging characteristics. The imaging features are discussed with a pathologic 

correlation approach to emphasize the key differences that in many cases can 

help narrow the differential diagnosis. 

Index terms: Spleen, abscess, 775.2054, 775.2056, 775.2057, 775.21 #{149} Spleen, cyst, 775.3121 #{149} Spleen, infarction, 

775.795 . Spleen, injuries, 775.412 #{149} Spleen, neoplasms, 775.3194, 775.33, 775.34 

RadioGrapb.ics 1996; 16:107-129 

I From the Department of Radiology (MU., P.J.M., G.M.T., P.R.R.), University of florida College of Medicine, 1600 SW Ar- 

cher Rd, Box 100374, Gainesville, FL 32610-0374; the Department of Radiology, Complejo Hospitalario de Ia Caja de 

Seguro Social, Panama, Republic of Panama (MU.); Hospital Miguel Servet, Universidad de Zaragoza, Zaragoza, Spain 

(LH.R.); and the Department of Radiologic Pathology, Armed Forces Institute of Pathology, Washington, DC (P.R.R.). Re- 

cipient of a Certificate of Merit award at the 1994 RSNA scientific assembly. Received February 21 ,1995; revision re- 

quested April 3 and received June 6; accepted June 7. Address reprint requests to PJ.M. 

cRSNA, 1996 

107

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Figure 1. True cyst. (a) Photomicrograph (original 

magnification, x4; hematoxylin-eosin stain) shows a 

large cyst (*) with a true endotheial lining (arrows) 

in the inner surface of its wall. (b) Photograph of a 

cut section of the spleen shows a large cyst with thin 

trabeculae (arrows). (C) Contrast material-enhanced 

CT scan of an asymptomatic patient with a left-upperquadrant 

mass shows a well-defined, low-attenuation 

mass with thin peripheral septations located posteriorly 

(arrows). 

. CONGENITAL MASSES 

. True Cyst 

True cyst, also called congenital and epider- 

moid cyst, is defmed by the presence of an in- 

ncr endotheial lining. It is developmental in 

origin, and its lining is formed secondary to an 

infolding of peritoncal mesotheium or collec- 

tions of peritoneal mesotheial cells trapped 

within the splenic sulci (1). 

Pathologic Features.-At microscopic examination, 

the inner wall is lined with a thin layer 

of endotheium (Fig ia). At gross examination, 

usually a large cyst with glistening, smooth 

walls and occasional trabeculae or septations is 

seen (2,3) (Fig ib). 

C. 

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- - 

Table 1 

Classification of Cystic Masses of the Spleen 

Classification Cystic Entity 

Congenital True cyst 

Inflammatory Pyogenic abscess, echino- 

coccal cyst, fungal abscess 

Vascular Infarction, peliosis 

Posttraumatic Hematoma, false cyst 

Neoplastic 

Benign Hemangioma, lymphangioma 

Malignant Lymphoma, metastasis 

108 U Scientific Exhibit Volume 16 Number 1 

‘:‘ 

-I

a. b. 

Figure 3. Pyogenic abscess. (a) Photomicrograph (original magnification, x12; hematoxylin-eosin stain) of the 

wall of an abscess shows severe inflammatory infiltrate and hemorrhage (arrows), with destruction of the normal 

splenic tissue. Internal debris also can be seen (arrowheads). (b) Photograph of a cut section of the spleen 

shows a large abscess with irregular nodular borders in the superior aspect of the spleen. Disruption of the capsule 

can be seen (arrows). 

Figure 2. True cyst. T2-wcighted MR image (2,500/ 

80) [repetition time msec/echo time mscc]) shows a 

well-defmed, rounded mass with high signal intensity 

(arrows) that corresponds to a small splemc 

cyst. 

Imaging Features.-On ultrasound (US) images, 

a wdll-defmed, anechoic mass is seen, 

with occasional low-level internal echoes see- 

ondary to the deposition of cholesterol crystals. 

True simple cysts of the spleen meet the US 

and computed tomographic (CT) criteria for 

cysts, as do cysts in the kidney and liver (1,2,4). 

CT typically shows a large, low-attenuation, 

unilocular mass with imperceptible walls; the 

attenuation of the mass is in the range of that of 

water (Fig ic). No enhancement is seen after 

the administration of contrast material, except 

possibly in the internal trabeculac (5). Magnetic 

resonance (MR) images show a well-defmed, 

round mass. On T2-weighted images, the mass 

has markedly high signal intensity, a character- 

istic fmding of a cyst (6) (Fig 2). 

. INFLAMMATORY MASSES 

. Pyogenic Abscess 

A splenic abscess is a localized collection of pus 

that most commonly is caused by the hematogenous 

spread of infection (75% of cases). Other 

causes include penetrating trauma (15%) and 

prior splcnic infarction (10%) (1). Pyogenic ab- 

scesses can be single or multiple. The clinical 

fmdings of fever, chills, and left-upper-quadrant 

pain and tenderness arc seen in less than half of 

the cases. 

Pathologic Features .-Suppuration or liquefactive 

necrosis can be seen, depending on the 

time course, within the abscess at microscopic 

examination (Fig 3a). At gross examination, ab- 

scesses can be seen to have irregular borders 

January 1996 Urrutia et al U RadioGraphics U 109

a. b. 

Figure 5- Pyogenic abscess. (a) Photograph of a cut section of the spleen shows an intrasplenic abscess (arrows) 

with a subcapsular collection of pus (arrowheads). (b) Postcontrast CT scan shows a low-attenuation 

mass with irregular borders (arrows). Subcapsular, low-attenuation collections (arrowheads) due to extension 

of the infectious process also can be seen. 

and no capsule or pseudocapsule (Figs 3b, 4, 

5). Rupture of the abscess into the perisplenic 

or subcapsular space sometimes occurs. 


a. 

Imaging Features.-Abscesses appear at US 

as poorly defined hypoechoic or anechoic 

masses (Fig 6), depending on the degree of proteinaccous 

fluid within the lesions. If gas has 

formed within the abscess, high echogenicity 

associated with distal “dirty” shadowing can be

Figure 7. Fungal abscess. (a) Photomicrograph (original magnification, x4; hematoxylin-cosin stain) shows 

multiple, small, rounded lesions with the typical target appearance (arrows). The dead hyphae of candidal organisms 

form the pale center of the target (*). The dark blue periphery represents the viable hyphae sur- 

rounded by a light, thin rim (arrowheads) of inflamed, compressed splenic parenchyma. (b) Photograph of a 

cut section of the spleen shows multiple white nodules of variable size (arrows) throughout the parenchyma 

that correspond to candidal abscesses. Scale is in centimeters. 

Figure 6. Pyogenic abscess. Sonogram shows a 

large, hypoechoic mass with internal low-level echoes 

and irregular borders (arrowheads). 

seen. However, CT is the most reliable method 

of identifying small amounts of gas (Fig 4b) 

(5,7,8). CT scans show a more well-defmed lesion 

than is typically shown on US images. No 

internal contrast enhancement is evident at CT 

(Fig Sb). Attenuation measurements range from 

20 to 40 HU; layers of different attenuation val- 

ues, secondary to layering of the proteinaceous 

material within the abscess, arc frequently 

noted. Rim enhancement may be shown, although 

it is seen less often in these lesions than 

in hepatic abscesses. 

. Fungal Abscess 

Fungal abscesses arc almost always multiple 

and occur most commonly in immunocompromised 

individuals. The most frequently encoun- 

tered pathogens are Candida albicans, As- 

pergillusfumigatus, and Cryptococcus neoformans 

(1,8). 

Pathologic Features . -At microscopic exami- 

nation, concentric rings can be seen with central 

necrotic hyphac; these rings are surrounded 

by viable hyphae and a rim of peripheral inflam- 

mation (Fig 7a) (2,3). At gross examination, the 

entire spleen may be seen to have innumerable 

small (less than 5 mm in diameter) fungal de- 

posits (Fig 7b). 

January 1996 Urrutla et al U RadioGraphics U 111

a. b. 

Figure 8. Fungal abscess in a 45-year-old man with 

known acute myeloid leukemia. (a) Sagittal sonogram 

shows multiple, subtle hypoechoic areas throughout 

the spleen (arrows). (b) Contrast-enhanced CT scan 

depicts multiple, well-demarcated, low-attenuation 

splenic lesions (arrows). (C) Proton density-weighted 

MR image (2, 100/45) shows multiple, well-defined, 

rounded areas of high signal intensity that are well demarcated 

from the adjacent splenic parenchyma. 

Imaging Features .-Multiple hypoechoic ar- 

eas (Fig 8a) with a “target” appearance are typi- 

cally seen at US; these findings correlate with 

the microscopic fmdings. The central nidus of 

necrotic hyphac is hypoechoic and is surrounded 

by a hypcrcchoic concentric band of 

viable fungal elements, which is in turn en- 

cased by a hypoechoic zone of inflammation 

(9). This structure results in the “wheel-withina-wheel” 

pattern (2,8). Small, low-attenuation 

areas that are usually well demarcated and that 

range from a few millimeters to 2 cm in size are 

shown at CT (2,6). Rim enhancement is not 

seen (Fig 8b). 

At MR imaging, the fungal deposits appear as 

multiple, round foci, which are hypointense on 

Tl-weightcd images and hyperintense on T2weighted 

images (8) (Fig 8c). 


C. 

. Echinococcal Cyst 

Hydatid cyst usually involves the liver or lungs 

but occasionally may also involve the spleen. It 

is not often seen except in areas where it is endemic, 

including Argentina, Greece, and Spain. 

It is almost always caused by Echinococcus 

granulosus (1,3). Clinical fmdings are nonspecific 

and frequently include abdominal pain, fever, 

and splenomegaly. 


the wall of the hydatid cyst is seen to be 

composed of an inner germinal layer and an

10. 

e) 

outer laminated membrane. These layers are 

surrounded by a thin band of fibrotic, compressed 

spleen, called pericyst. Scolices and 

fragments of the germinal layer constitute the 

so-called hydatid sand within the cyst (2,3). At 

gross examination, the cysts arc seen to be cither 

unilocular or multiocular. Loculi form in 

the periphery, due to invaginations in the germinal 

layer, and result in the formation of 

daughter cysts (Fig 9a). 

Imaging Features.-Most splenic hydatid 

cysts appear as cystic lesions at US, with small 

daughter cysts in the periphery of the main 

cyst. A mixed pattern of echogenicity, pro- 

9b. 

‘ . .. 

Figures 9, 10. Hydatid cyst. (9a) Photograph of a cut 

section of the spleen shows a large, uniocular hydatid 

cyst. Note the white, laminated membrane attached to 

the spleen (straight arrows). The germinal layer has 

been peeled off (arrowheads). A single daughter cyst 

can be seen (curved arrow). (9b) Contrast-enhanced CT 

scan shows a well-demarcated, low-attenuation mass in 

the spleen that contains two daughter cysts (arrows). 

(Courtesy of Tomas Franquet, MD, Hospital St Pau, 

Barcelona, Spain.) (10) Contrast-enhanced CT scan 

shows a round splenic mass that is sharply marginated 

and has rimlike calcifications (arrowheads). Hydatid 

sand can be seen within the mass (*), as can the peripheral 

budding of a daughter cyst that also is calcified 

(straight arrows). The lesion on the right (curved arrows) 

represents an additional hydatid cyst that extends 

up to the inferior aspect of the liver. 

duced by the presence of infolding membranes 

and hydatid sand, can be seen occasionally 

(2,10). CT demonstrates a sharply marginated, 

round or ovoid mass that has attenuation in the 

range of that of water (Fig 9b). Ringlike calcifi- 

cations may be seen in the periphery, within 

the pericyst. Higher attenuation within the le- 

sion is frequently encountered and may occur 

secondary to the formation of daughter cysts or 

as a result of the collection of dense debris (hy- 

datid sand) within the cyst (Fig 10) (2,6). 


Figure 11. Infarction. (a) Photograph of a cut see- 

tion of a massively infarcted spleen. Multiple cystic ar- 

eas with irregular borders can be seen throughout the 

spleen. These areas correspond to a cystic form of 

splenic infarction. (b) Transverse sonogram of the 

same patient shows a heterogeneous, complex splemc 

mass and scattered, rounded, hypoechoic areas 

throughout the parenchyma (arrows) caused by the 

hemorrhagic debris of infarction. (c) Contrast-enhanced 

CT scan shows multiple areas of low attenua- 

tion (*), secondary to infarction and necrosis. 

b. c. 

. VASCULAR MASSES 

. Infarction 

Infarction can be either arterial or venous; arte- 

rial infarction occurs secondary to occlusion of 

the splenic artery or its branches, and venous 

infarction is caused by thrombosis of the sple- 

nic sinusoids, which also occurs in patients 

with massive splenomegaly. In the first instance, 

arterial occlusion leads to infarction because 

the vessels are endarteries and there is no 

intercommunication for the reestablishment of 

arterial supply (1). Causes of arterial occlusion 

include thromboembolic diseases, such as 

hemolytic anemias and endocarditis, which may 

be seen in patients who are abusing intravenous 

drugs or who have valvular heart disease, 


a. 

systemic lupus erythcmatosus, arteritides, or 

pancreatic carcinoma. In patients with venous 

infarction, massive splenomegaly results in 

marked reduction of the splenic blood flow, 

which causes sinusoidal thrombosis. Patients 

with arterial or venous infarction present cmically 

with splenomegaly and acute upper quad- 

rant pain, which worsens on deep inspiration. 


necrotic, infarcted areas may be either 

ischemic (arterial) or hemorrhagic (venous). 

Occasionally, infarctions may be cystic, espe- 

cially in the acute phase. In late phases, the ar- 

eas of infarction become fibrotic (3). At gross 

examination, infarctions have a varied appear- 

ance, depending on their stage of evolution. 

Acute infarctions frequently have an increased 

volume due to edema; chronic infarctions have 

a reduced volume secondary to fibrosis. Lique-

a. b. 

Figure 12. Infarction in a 24-year-old woman with a hypercoagulable state related to pregnancy. (a) Longitudinal 

sonogram shows a well-defmed, hypoechoic mass in the inferior splenic pole (straight arrows). A large 

area of infarction also can be seen in the superior pole. The infarction is heterogeneous and predominantly 

hyperechoic (curved arrow), revealing that it is not truly cystic but is full of hemorrhagic, necrotic debris, as 

seen at pathologic examination. (b) Contrast-enhanced CT scan shows a well-defined area of low attenuation 

corresponding to the area of infarction in the superior portion of the spleen and mimicking a cystic lesion (the 

inferior pole infarction had a similar CT appearance, although it is not shown). 

factive necrosis sometimes occurs, in which 

case the areas of infarction contain scrosanguin- 

eous material, which causes the masses to have 

a cystic appearance (Fig 1 ia) (2,6). 

Imaging Features .-Areas of decreased 

echogenicity with ill-dcfmed margins arc 

shown at US, without the sonographic characteristics 

of a true cyst (Figs 1 1 , 1 2a). With time, 

areas of infarction become more rounded and 

better delineated, secondary to the ensuing fi- 

brotic reaction (1 i). 

CT features of splenic infarction also vary, 

depending on the phase of infarction. In the 

acute phase, well-dcfmcd areas of decreased at- 

tenuation are present (Fig 1 2b) (8). In the subacute 

phase, these areas have markedly low at- 

tenuation, which makes differentiation from 

other cystic masses difficult (Fig 1 ic) (1). In 

these cases, US can be used to help narrow the 

differential diagnosis because it shows that the 

lesions are not truly cystic (Fig 12a) (2,6). 

MR images will show varying signal intensity 

characteristics, depending not only on the stage 

of infarction but also on the hemorrhagic or 

nonhcmorrhagic nature of it. The appearance of 

subacute or chronic arterial infarction would be 

similar to that of a cyst, with low signal intensity 

on Ti-weighted images and high signal in- 

tensity on T2-wcightcd images. The signal intensity 

of venous infarction will vary with the 

phase of evolution of the blood products. 

. Peliosis 

This rare entity is characterized by the presence 

of widespread blood-filled cystic spaces within 

the splenic parenchyma. These cavities vary in 

size and may or may not contain an endothelial 

lining. Thrombosis within the blood-filled 

spaces also may occur. The cause of splenic 

peliosis is unknown, although it may be associ- 


Figure 13. Peliosis in a patient who underwent splenectomy after experiencing blunt ab- 

dominal trauma. (a) Photomicrograph (original magnification, xi2; hematoxylin-eosin stain) 

shows hemorrhage within the vascular cavities (arrows), a finding that is typical of peliosis. 

No endothelial lining is present. (b) Photograph of a cut section shows diffuse, multiple cystic 

cavities of variable size filled with clotted blood (arrows). (c) Contrast-enhanced CT scan 

shows multiple low-attenuation, rounded lesions of different sizes throughout the splenic parenchyma; 

these lesions were thought to be intrasplenic hematomas preoperatively. Note 

also the hemoperitoneum (*), which occurred secondary to other traumatic abdominal insult 

and was unrelated to the splenic peliosis. Scale is in centimeters. 

ated with malignant hematologic diseases (such 

as Hodgkin disease and mycloma), disseminated 

cancer, tuberculosis, use of anabolic and contraceptive 

steroids, prior thorium dioxide (Thor- 

ii6 U Scientific Exhibit Volume 16 Number 1 

a. 

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otrast) injection, and certain viral infections 

(1 2). Patients with splenic peliosis arc usually 

asymptomatic. It is usually detected incidentally 

from imaging studies or at autopsy. 

Pathologic Features-At microscopic exami- 

nation, vascular channels, which are typically 

filled with blood, are seen with or without an

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endothelial lining (Fig 1 3a). In peliosis, the cystic 

cavities are closely spaced without inter- 

posed connective tissue septa, unlike in hemangiomas 

(12). At gross examination, peliosis fre- 

quently is seen to involve the entire spleen, 

with multiple, small, blood-filled, cystic spaces 

(Fig 13b). 

Imaging Features.-On US images, multiple 

hypoechoic or hyperechoic lesions without 

sharply demarcated borders are seen; these lesions 

may occupy the entire spleen. CT simi- 

larly shows multiple low-attenuation foci (Fig 

1 3c). The enhancement pattern is similar to 

that of hemangiomas, with dynamic images 

showing low-attenuation lesions immediately after 

intravenous administration of contrast mate- 

rial, with eventual slow centripetal enhancement 

(2). The MR imaging appearance of 

peiosis in the spleen is not well established. 

I 

Figure 14. Multiple intrasplenic hematomas due to 

trauma. (a) Photomicrograph (original magnification, 

x6; hematoxylin-cosin stain) of a specimen slice reveals 

fragments of normal splenic parenchyma (*) and 

large collections of blood (arrows). Multiple concen- 

tric layers due to differing stages of clot formation can 

be seen. ,) Sagittal sonogram depicts a heterogeneous 

spleen, with multiple hypoechoic collections of 

blood, especially in the lower pole (arrows). (C) Contrast-enhanced 

CT scan of the same patient as in b 

shows multiple, well-defined, low-attenuation foci 

scattered throughout the spleen and corresponding to 

regions of hematoma. 

I POS1TRAUMA11C MASSES 

. Hematoma 

Intrasplenic hematoma is diagnosed when 

extravasated blood is present within the splenic 

pulp. Clinical symptoms may include pain and 

left-upper-quadrant tenderness after blunt or 

penetrating abdominal trauma, splenic biopsy, 

or anticoagulation therapy. 

Pathologic Features.-At microscopic exami- 

nation, blood in different stages (from wellformed 

clot to lysed serosanguincous fluid) can 

be seen within the spleen (2,3). There is no delincating 

cell layer between the fluid contents 

and the surrounding normal splenic pulp (Fig 

i4a). At gross examination, blood is seen within 

the spleen and frequently tracks into the subcapsular 

or perisplenic spaces. 


a. b. 

Figure 15. False cyst. (a) Photomicrograph (original magnification, x6; hematoxylin-cosin stain) shows the 

thick wall of a false splenic cyst (double-headed arrow) surrounded by compressed splenic parenchyma (arrowheads). 

The inner surface of the wall has no lining. (b) Photograph of a gross specimen shows a 7-cm, unilocular 

cyst filled with brownish, cloudy fluid. The thick, fibrous wall (arrows), as well as the smooth, nontrabeculated, 

inner surface, can be seen clearly. 

Imaging Features.-US images show a welldefined, 

hypoechoic focus within the splenic 

parenchyma (Fig i4b) (13). At CT, a low-attenuation, 

nonspecific, cystic lesion with clear-cut 

margins is seen (14, 1 5). Hematomas do not enhance 

but are more apparent on contrast-en- 

hanced images because the attenuation of the 

normal splenic parenchyma increases, which 

increases the lesion-to-spleen contrast (Fig i4c) 

(16). 

The MR imaging characteristics differ depending 

on the phase of evolution of the hema- 

toma. After 3 weeks, a hematoma appears as a 

cystic mass with low signal intensity on Ti- 

weighted images and high signal intensity on 

T2-weighted images. Hemosiderin rings may be 

noted (2,6). 

. False Cyst 

Posttraumatic or false cyst (nonpancreatic 

pseudocyst of the spleen) is believed to be the 

end stage of intrasplenic hematoma (2,4,5). 

Posttraumatic cysts account for 80% of all splenic 

cysts. They are pseudocysts because they 

do not contain an inner endotheial lining; they 

are therefore false cysts by definition (5). A remote 

history of trauma to the left upper quadrant 

can often be ascertained. 


nation, pseudocysts are characterized by a 

thick, fibrous wall without an inner endotheial 

cell layer (Fig i 5). At gross examination, false 

cysts are usually smaller than true cysts and 

may contain internal debris. Calcifications may 

be seen within the thick fibrous wall. Septations 

are exceedingly rare. 

Imaging Features.-It is impossible to clearly 

distinguish between true and false cysts at US 

examination. However, certain characteristics 

help identify false cysts. Their smaller size; internal 

echoes from debris; and peripheral, 

brightly echogenic foci with distal shadowing 

due to calcifications within the fibrous wall (Fig 

i6a) are all correlative US features that aid in 

distinguishing false from true cysts. 

On CT scans, false cysts appear as sharply 

demarcated masses with the same attenuation 

as that of water. Peripheral calcifications within 

118 U Scientific Exhibit Volume 16 Number 1

a. b. 

Figure 16. False cyst (incidental fmding) in a 40-year-old woman with congestive heart failure. (a) Oblique 

sonogram of the left upper quadrant shows a well-defined, rounded splenic mass with a thick wall and brightly 

echogenic, partially shadowing calcifications (arrowheads). Low-level echoes can be seen within the mass (*), 

which was presumed to be cystic. (b) Contrast-enhanced CT scan shows uniform low attenuation of the cystic 

splenic lesion, with calcification within the wall. Ascites (*) due to congestive heart failure also can be seen. 

the fibrous wall may resemble eggshell (Fig 

16b) (4,6). 

The MR imaging appearance is similar to that 

of true cysts. A false cyst appears as a well-dc- 

fmed, rounded mass with very high signal inten- 

sity on T2-weighted images but variable signal 

intensity on Ti-weighted images, depending on 

the degree of proteinaceous material or hemorrhage 

present. 

. BENIGN NEOPLASTIC MASSES 

. Hemangioma 

Hemangioma is characterized by a proliferation 

of vascular channels of variable size that are 

lined with a single layer of endotheium and 

filled with red blood cells. Although hemangiomas 

are very rare, they represent the most 

common primary neoplasm of the spleen (17). 

They usually are asymptomatic and are discovered 

incidentally, but very large masses can produce 

pain and splenomegaly. 

Pathologic Features . -At microscopic exami- 

nation, splenic hemangiomas arc indistinguishable 

from hemangiomas in other areas of the 

body, such as the liver. The vascular channels 

that form splenic hemangiomas vary in size 

from capifiary to cavernous (Fig 17a) and are 

typified by slow-flowing blood. Areas of fibrosis 

occur less commonly than they do in hepatic 

hemangiomas. However, cystic areas arc very 

common in hemangiomas of the spleen, hence 

its inclusion in the differential diagnosis of cys- 

tic splenic masses. 

At gross examination, single or multiple 

masses may be seen, sometimes replacing the 

entire spleen (angiomatosis). They may occur 

as part of generalized angiomatosis such as 

Klippel-Tr#{233}naunay-Webcr syndrome (1 ,2) and 

may range from a few millimeters to many cen- 


Figure 17. Hemangioma. (a) Photomicrograph (original magnification, x6; hematoxylin-eosin stain) shows the 

characteristic multiple blood-filled vascular channels. There are cystic areas that were filled with serous materi- 

al (*) instead of blood. Architectural distortion of the areas can be seen when they are compared with the surrounding 

normal splenic parenchyma (arrowheads). (b) Photograph of a cut section shows a large hemangioma, 

which replaces almost the entire visible spleen. The hemangioma can be seen to contain a large cystic space (arrows) 

filled with hemorrhagic debris. (C) Sagittal sonogram of the left upper quadrant shows a cystic mass (arrowheads) 

with internal trabeculation (arrows). A second complex mass (*) in the superior aspect of the spleen 

can also be seen. (d) Contrast-enhanced CT scan of the same patient as in c shows multiple, low-attenuation, 

well-defined masses within the splenic parench-’ma that correspond to the blood-filled vascular channels. 

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timeters in size. The lesions can be entirely cys- 

tic or solid with some cystic elements (Fig 

1 7b). The contents of the cystic areas range 

from serous to hemorrhagic. 

Imaging Features.-The imaging appearance 

varies depending on the gross morphology and 

ranges from predominately solid to mixed (with 

cystic and solid portions) to purely cystic. At 

US, small cystic areas arc frequently seen within 

an echogenic mass (Fig 18) (1 1), although pre- 

dominantly cystic hemangiomas can be seen oc- 

casionally (Fig 17c). Color Doppler flow US 

may show blood flow within the solid portions 

(18). 

Unenhanced CT scans may show low-attenuation 

lesions that resemble cysts (Fig 17d). ASter 

contrast material administration, there is delayed 

enhancement within the solid portions 

secondary to the slow filling of the vascular 

channels (Fig 19a, 19b). Central, punctate calci- 

fications can be seen in the solid portions, and 

curvilinear calcifications may be seen in the periphery 

of the cystic areas (Fig 18b). 

On MR images, hemangiomas in the spleen 

resemble those in the liver, with low signal in- 

tensity on Ti-weighted images (Fig 19c) and 

markedly high signal intensity on T2-wcight- 

ed images (19). High signal intensity on Tiweighted 

images suggests the presence of sub- 

acute hemorrhage (6,8). 


Figures 18, 19. (18) Hemangioma. (a) Sagittal sonogram shows a large, complex, hyperechoic mass (arrows), 

with scattered internal hypoechoic foci (arrowheads). (b) Contrast-enhanced CT scan shows a predominantly 

low-attenuation splenic mass (*). The anteromedial speckled calcification (arrowheads) can be seen in a 

more isoattenuating portion of the lesion. (19) Multiple hemangiomas in a 76-year-old woman. (a) Dynamic, 

contrast-enhanced CT scan obtained immediately after the intravenous administration of contrast material 

shows multiple well-defined, rounded, low-attenuation lesions throughout the spleen, with slight peripheral enhancement. 

(b) CT scan obtained 2 minutes after contrast material administration shows centripetal enhancement 

(arrows) of the lesions, characteristic of hemangioma. Two hepatic hemangiomas (* in a and b) can also 

be seen (the patient had angiomatosis). (c) Tl-weighted MR image (450/15) shows small, hypointense foci (ar- 

r”- I A1 I..A.. 11 :...... n.......,._. n........i r’i. si:.L 

19C. 

January 1996 Urrutia et al U RadioGrapbics U 121

a. b. 

Figure 20. Lymphangioma. (a) Photomicrograph (original magnification, x6; hematoxylin-cosin stain) shows 

foci of lymphangioma (arrowheads), which appear as multiple lymph-filled channels, surrounded by normal 

splenic parenchyma (*). (b) Photograph of a cut section of the spleen shows numerous cystic spaces (arrows) 

containing clear, yellowish fluid consistent with lymph. Septations (arrowheads) within the lymphangioma can 

be seen. 

. Lymphangloma 

Lymphangioma, another vascular lesion like hemangioma, 

is filled with lymph instead of red 

blood cells. Splenic lymphangiomas may be 

single or multiple (lymphangiomatosis) (2). 

Like hemangiomas, they can involve the spleen 

exclusively, or they may be part of generalized 

angiomatosis, with lymphangiomas or heman- 

giomas involving several organs in the body. 

Lymphangiomas arc usually asymptomatic. 


nation, lymphangiomas arc seen to be cornposed 

of multiple vascular channels that arc 

lined with a single layer of endothelium and 

filled with proteinaccous fluid (lymph) (Fig 

20a) (3). Small areas of hemorrhage may be 

present within lymphangiomas. At gross examination, 

they may appear as unilocular or multilocular 

cystic masses (Fig 20b); they may be 

solitary or may involve the entire spleen (lym- 

phangiomatosis). The contents are serous to 

chylous. 

Imaging Features.-At US examination, 

lymphangiorna appears as a well-defined, hypo- 

echoic mass that may have internal septations 

and occasional echogenic debris within the 

fluid-filled loculi (Fig 2ia). CT features include 

splenomegaly, with single or multiple areas of 

low attenuation. Lymphangiomas are sharply 

marginated and are not enhanced on postcon- 

trast images (Fig 2ib) (20). Small, marginal, linear 

calcifications may be present. The MR imaging 

appearance of the lesions is very similar to 

that of cysts, with homogeneously low signal 

intensity on Ti-weighted images (Fig 21c) and 

high signal intensity on T2-weighted images 

(Fig 2 id). Areas of high signal intensity may be 

shown on Ti-weighted images if internal hemorrhage 

is present or if the lesions contain a 

large amount of protcinaceous fluid (Fig 2 ic). 

U MALIGNANT NEOPLASTIC MASSES 

. Lymphoma 

Lymphoma, which is a generalized lymphoprolucrative 

disorder, constitutes the most corn- 

mon malignant splenic neoplasrn and involves 

the spleen in both Hodgkin and non-Hodgkin 

types. Patients usually present with nonspecific, 

systemic clinical symptoms, as well as en- 

largement of the spleen (in up to 80% of patients). 

Findings associated with a lymphoma 


a. b. 

C. d. 

Figure 21. Multiple lymphangiomas in a 74-year-old woman. (a) Sagittal sonogram depicts multiple hypoechoic, 

rounded masses of different sizes. The largest mass contains low-level echoes (arrows) due to the pro- 

teinaceous nature of its contents. (b) Contrast-enhanced CT scan shows multiple nonenhancing lesions (straight 

arrows) throughout the spleen, with the normal splenic architecture being almost completely replaced. The 

largest focus is subcapsular in location (curved arrow). (C) Ti-weighted MR image (450/1 5) reveals variably 

sized foci of low signal intensity. Some of the lesions have areas of high signal intensity (arrow), indicating the 

presence of proteinaceous material within them. (d) T2-weighted MR image (2,000/90) shows multiple lesions 

of variable size with marked hyperintensity. 

can mimic those of an abscess and may include secondarily infected, which results in abscess 

fever, left-upper-quadrant pain, and spleno- formation. 

megaly. Splenic lymphomas sometimes become 

January 1996 Urrutia et a! U RadioGraphics U 123

1 

C. ci 

y 

Figure 22. Lymphoma. (a) Photomicrograph (original magnification, x6; hematoxylin-eosin stain) shows diifuse 

infiltration of the spleen by lymphoma (*). A small amount of normal splenic parenchyma can be seen cornpressed 

against the capsule (double-headed arrow). (b) Photograph of a cut section of the spleen shows mIlltrating 

lymphorna (*) with a central cystic area (arrowheads). (C) Longitudinal sonogram of the same patient as 

in b shows a complex mass with an ill-defined, central hypoechoic area (*) corresponding to the central cystic 

region seen at pathologic examination. Acoustic enhancement is also present, accounting for some of the increased 

echogenicity within the lesion. (d) Contrast-enhanced CT scan shows a large, ill-defined mass with low 

attenuation. No adenopathy can be seen. 

Pathologic Features.-There are three differ- 

ent macroscopic patterns of splenic lymphoma: 

(a) infiltrative, without defmitc discrete masses 

(Fig 22a); (b) miliary, with small (

a. b. 

C. 

Imaging Features.-Thrcc patterns are seen 

at US that correspond to the pathologic type of 

involvement: (a) diffuse heterogeneity with dis- 

ruption of the normal splenic sonographic architecture; 

(b) small, nodular, hypoechoic le- 

. sions less than 2 cm in diameter; and (c) large, 

focal, hypoechoic lesions that may be cystlike. 

These lesions may be markedly hypoechoic and 

thus may resemble cysts on US images; how- 

ever, they lack acoustic enhancement (13). Internal 

necrosis also will result in a cystic appearance 

on US images (Fig 22c). 

The CT appearances of splenic lymphoma 

also reflect the spectrum of pathologic patterns 

that occur, ranging from splenomegaly alone to 

Figure 23. Diffuse, histiocytic lyrnphorna. (a) Con- 

trast-enhanced CT scan shows that almost the entire 

spleen has been replaced with lymphoma. A periphcmi 

area of low attenuation (arrows), representative 

of a focal area of necrosis, can be seen. (b, C) The 

“cystic” area seen in a is hyperintense (arrows) on the 

Ti-weighted (600/i 5) image (b) and T2-weighted 

(2,000/90) image (c) secondary to the protemnaceous 

nature of the necrotic material. The entire spleen has 

heterogeneously increased signal intensity on T2weighted 

images (c), secondary to the diffuse involve- 

ment with lymphoma. 

miliary multifocal lesions to a solitary mass. Ar- 

eas of lymphoma larger than 1 cm in diameter 

are usually detectable with CT and usually ap- 

pear as discrete, low-attenuation masses (2,6). 

These lesions are not enhanced on postcontrast 

images. When necrosis is present, attenuation is 

in the range of that of water (Figs 22d, 23a), 

and differentiation from other cystic entities 

such as abscesses (Fig 22d) is difficult. 

The areas of lymphoma appear as slightly hypointcnse 

foci on Ti-weighted MR images and 

as hyperintense foci on T2-wcighted MR images 

(2 1). MR imaging cannot reliably depict infiltra- 

tive lymphoma, contrary to initial expectations 

(2,8), because both normal spleen and lymphomatous 

infiltrated spleen may have similar Ti 

and T2 values. Areas of necrosis or old hemorrhage 

within lymphomas are easier to detect 

due to substantially increased T2 values (Fig 

23b, 23c). 


a. b. 

Figure 24. Metastases from colonic adenocarcinoma. 

(a) Photomicrograph (original magnification, 

x4; hematoxylin-cosin stain) shows compression of 

the normal splenic parenchyma (arrowheads) by 

neoplastic tissue composed of mucous glands (*). 

The splenic capsule is intact (arrow). (b) Photograph 

of a cut section of the splenectomy specimen 

shows the splenic capsule (arrows) and the compressed 

normal spleen (arrowhead). The remainder 

of the spleen has been replaced by a large metastasis 

(*). Massive central necrosis can be seen. Scale is in 

centimeters. (c) Transverse sonogram of the same 

patient as in a and b reveals a complex mass with irregular, 

hypoechoic areas (arrows) and central 

hyperechogenicity (*), secondary to necrotic debris 

within the mass. 

. Metastasis 

Metastatic involvement of the spleen is relalively 

uncommon. It is seen in only 7% of pa- 

tients with widespread malignancy (8). Fifty 

percent of all splcnic metastases are due to 

melanoma, and the remaining 50% are predominantly 

due to adenocarcinoma of the breast, 

lung, colon, ovary, endometrium, and prostate 

(2). Large metastases may cause left-upper- 

quadrant pain, although smaller lesions arc of- 

ten asymptomatic. 

Pathologic Features . -At microscopic examination, 

the appearance of metastases varies depending 

on the tumor of origin. Many metasta- 

ses in the spleen are cystic, secondary to rapid 

growth, resulting in autoinfarction, internal ne- 

crosis, or both (Fig 24). At gross examination, 

C. 

r-. F 

.:. . 


“:: 

?! 

the spleen is usually seen to be normal in size 

with multiple small foci or solitary large foci 

(Figs 24, 25). 

Imaging Features.-In most instances, the 

metastases are hypoechoic on US images. Lowlevel 

echoes may be seen within cystic metasta- 

ses, secondary to the presence of internal de- 

bris (Fig 24c). Occasionally, the lesions are entirely 

hyperechoic (Fig 26a). 

At CT, metastases may appear as ill-defined, 

low-attenuation foci (Fig 26b) or as well-delineated, 

uniocular or septated lesions (Figs 25b, 

27a) with the same attenuation as water (Fig 

2Sb) (20). Enhancement may be present in the 

periphery and in viable internal septa (Fig 25b) 

(8). Percutaneous needle biopsy or aspiration 

may be performed to help determine a defini- 

tive diagnosis in patients with a history of a 

known malignancy.

: 1 : 

- 

::- 

- . . 

-,. .(- . .- 

I_ ;.;;- 

- . ;: , 

::.:i.;, : I”- 

. ‘ 1 . , . ..., A 

i.e 

Figures 25, 26. (25) Metastases from ovarian cystadenocarcinoma. (a) Photograph of a cut section of the 

splenectomy specimen shows large, metastatic foci within the spleen, ranging from cystic (*) to solid (arrows) 

in morphology. Scale is in centimeters. (b) Contrast-enhanced CT scan of the upper abdomen depicts multiple 

low-attenuation lesions (*) in the spleen, with thin walls (arrowheads) and no calcifications. The more solid pot- 

tion can be seen to enhance heterogeneously (arrows). (26) Metastases from melanoma. (a) Sagittal sonogram 

shows a solid, hyperechoic mass (arrowheads). (b) Contrast-enhanced CT scan shows a large, ill-defined lesion, 

with very low attenuation, in the posterior aspect of the spleen. 


a. b. 

Figure 27. Metastases from an unknown primary 

adenocarcinoma. (a) Contrast-enhanced CT scan 

shows a low-attenuation mass that is well demar- 

cated from the splenic parenchyma and has irregular 

borders. (b) Ti-weighted image (300/i 5) shows a 

focal lesion with low signal intensity. (c) On a T2weighted 

image (4,000/90), the lesion appears hyperintense 

because of its high water content. 

MR images of metastases typically show foci 

with low signal intensity on Ti-weighted images 

(Fig 27b); these foci become hyperintense 

on T2-wcighted images (Fig 27c) (22). The 

presence of blood products from hemorrhage 

or of other paramagnetic substances, such as 

melanin within melanomas, may result in high 

signal intensity on Ti-weighted images. 

. CONCLUSION 

The list of entities that may appear as cystic 

splenic lesions on US, CT, and MR images is cx- 

tensive. In addition, radiologic fmdings often 

have substantial overlap, which precludes the 

rendering of a specific diagnosis on the basis of 

imaging fmdings alone. In these instances, correlation 

of radiologic features with clinical and 

histologic findings is needed to confirm the di- 

agnosis. These lesions can, however, be classi- 

fled on the basis of their cause (Table 1), and 

the differential diagnosis can be somewhat narrowed 

by evaluating the imaging characteristics 

(Table 2). Thus, it is important to understand 

and recognize the spectrum of pathologic and 

imaging features of cystic splenic lesions. 


C. 

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Table 2 

Differential Diagnosis of Cystic Splenic Masses 

Multiple Thick, Thin, 

Cystic Splenic Single Cystic Unilocular Multilocular Peripheral Irregular Smooth 

Lesion Cystic Mass Masses Cystic Mass Cystic Mass Calcifications Borders Borders 

Congenital 

Truecyst +++ - +++ + - - +++ 

Inflammatory 

Pyogenic 

abscess +++ ++ ++ ++ - +++ - 

Echinococcal 

cyst ++ ++ + +++ ++ - +++ 

Fungal abscess - +++ +++ - - - 

Vascular 

Infarction ++ + ++ + - +++ ++ 

Peliosis + +++ +++ - - +++ + 

Posttraumatic 

Hematoma +++ ++ +++ + - ++ 

Falsecyst +++ - +++ + +++ - 

Neoplastic 

Benign 

Hemangioma + + ++ - ++ +++ - 

Lymphangioma ++ +++ + +++ + - 

Malignant 

Lymphoma + + + - - +++ - 

Metastasis +++ +++ ++ + - +++ ++ 

Note.-+++ = frequently occurs, ++ = occasionally occurs, + = rarely occurs, and - = never occurs. 

*Dependent on the stage of evolution of the hematoma. 

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This article meets the criteriafor 1.0 credit hour in Category I of the A.MA Physician ‘s Recognition 

Award. To obtain credit, see the questionnaire on pp 162-166 

January 1996 Uri-utia Ct a! U RadioGraphics U 129

.::: Cystic Masses of the Spleen: Radiologic- - RadioGraphics

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