Diagnostic ultrasound ( PDFDrive )

786 PART III Small Parts, Carotid Artery, and Peripheral Vessel Sonography
BREAST CANCER IS HETEROGENEOUS
Circumscribed
cellular
• Hyaluron matrix
• Immune cells
• High grade
• Enhanced sound
• Doppler +
...and mixed circumscribed
and spiculated between...
Spiculated
paucicellular
• Collagen matrix
• Desmoplastic
• Low grade
• Shadowing
• Doppler –
FIG. 21.38 Malignant Masses: Spectrum of Appearances. The appearance of breast cancer spans a spectrum from classic spiculated lesions
to circumscribed carcinomas. There are also mixed spiculated and circumscribed lesions in the middle of the spectrum. Sonographic indings for
circumscribed and spiculated lesions can be opposite from each other. Only by using multiple indings capable of identifying lesions at both ends
of the spectrum can carcinomas be identiied with the desired 98% or greater sensitivity.
nodules that is so likely to be benign that the patient can be
ofered the option of follow-up in addition to the option of biopsy.
BI-RADS 3 lesions must have a 2% or lower risk of being
malignant.
Before delving into the sonographic appearance of various
solid nodules it is important to gain an understanding of what
pathologic features contribute to the indings we see on ultrasound.
Fig. 21.38 illustrates the heterogeneity of breast cancer,
which can be thought of as spanning a spectrum from spiculated
to circumscribed lesions. Not only is breast cancer heterogeneous
from one mass to another, but it also can be heterogeneous
within an individual mass, and thus there is a peak of mixed
circumscribed-spiculated lesions in the center of the spectrum.
hese features should be considered when classifying a mass as
probably benign (BI-RADS 3) or classifying a mass as suspicious
and recommending a biopsy.
Spiculated and circumscribed cancers difer greatly. he
histologic and gross morphologic features of the spiculated and
circumscribed ends of the malignant spectrum difer in cellularity,
constituents of the extracellular matrix, host reaction to
the tumor, and water content. Spiculated or stellate malignant
lesions tend to be low to intermediate in histologic grade,
whereas circumscribed lesions tend to be either special-type
tumors (e.g., colloid or medullary carcinoma) or high-grade
invasive ductal carcinoma. he classic spiculated breast carcinoma
is composed of tumor cells, collagenous extracellular
matrix, and desmoplastic host response to the lesion. he
usually low-grade spiculated carcinomas are paucicellular—a
small percentage of the total volume of the lesion is composed
of tumor cells. he paucicellular nature, collagenous matrix, and
desmoplastic host response of spiculated malignant lesions
makes them relatively water poor, so they oten cause acoustic
shadowing. Circumscribed carcinomas, usually high-grade
invasive ductal carcinomas, on the other hand, are highly cellular.
hey have more hyaluronic acid in the matrix and manifest
a primarily lymphoplasmacytic immune response. he high
cellularity, hydrophilic hyaluronic acid matrix, and lymphoplasmacytic
response in circumscribed lesions makes them water
rich. 45 hus circumscribed lesions usually manifest increased
sound transmission.
Because breast tumors have varying histology, speciic sonographic
features do not universally apply to all malignancies.
For example, acoustic shadowing can help clinicians detect
lesions at the spiculated end of the spectrum and some of the
mixed lesions in the middle of the spectrum, but it is much less
efective at the circumscribed end of the spectrum. On the other
hand, Doppler ultrasound is very helpful for circumscribed
carcinomas because of their high tumor cellularity and associated
abundant angiogenesis factors. In addition, the lymphoplasmacytic
immune-inlammatory response of circumscribed carcinomas
causes vasodilation of surrounding vessels. Doppler is
not as helpful for spiculated lesions that have relatively few tumor
cells that elaborate angiogenesis factors. hese masses also have
a collagen matrix and desmoplasia that require little blood low.
As a result, spiculated lesions oten do not have perceptibly
increased low compared with benign lesions or normal tissue.
he heterogeneity of breast cancer therefore requires that multiple
diferent sonographic features be used to characterize masses to
detect cancer with adequate sensitivity.
he algorithm that we use to evaluate lesions must account
for internal heterogeneity by assessing the shape, orientation,
margin, echo pattern and posterior features of the lesion for
suspicious indings completely in two orthogonal planes (preferably
radial and antiradial). In lesions that have a mixture of
suspicious and nonsuspicious indings, it is important to focus
on the most suspicious indings.