Diagnostic ultrasound ( PDFDrive )

340 PART II Abdominal and Pelvic Sonography
manifestations are similar; early cortical calciication may be
suggested by increased cortical echogenicity. With progressive
calciication, a continuous, shadowing calciied rim develops.
GENITOURINARY TUMORS
Renal Cell Carcinoma
Renal cell carcinoma (RCC) accounts for approximately 3% of
all adult malignancies and 86% of all primary malignant renal
parenchymal tumors. 120 here is a 2 : 1 male predominance, and
peak age is 50 to 70 years. he cause is unknown, although
weak associations with smoking, 121 chemical exposure, asbestosis,
obesity, and hypertension have been shown. he vast majority
of RCCs are sporadic, but an estimated 4% occur in the
context of inherited syndromes. 122,123 hese “inherited” RCCs
occur at an earlier age, are multifocal and bilateral, and afect
FIG. 9.44 Medullary Sponge Kidney. Sagittal sonogram shows
markedly increased renal medullary echogenicity (“medullary rings”).
men and women equally. 122 Von Hippel–Lindau (VHL) disease
is the best known inherited RCC syndrome; 24% to 45% of
patients who have VHL disease will develop RCC. Most of
these lesions are multicentric and bilateral and are clear cell
carcinomas. 124-126 Other inherited renal cancer syndromes
include hereditary papillary renal cancer, Birt-Hogg-Dubé syndrome,
hereditary leiomyoma RCC, familial renal oncocytoma,
hereditary nonpolyposis colon cancer, and medullary RCC. An
increased incidence of RCC in patients with tuberous sclerosis
has also been reported. 123 Another important but nonsyndromic
risk factor for RCC is the acquired cystic kidney disease that
occurs in patients receiving long-term hemodialysis or peritoneal
dialysis. he RCCs in these patients are small and hypovascular
and tend to be relatively less aggressive. 127,128
Histologic subtypes of RCC include clear cell (70%-75%),
papillary (15%), chromophobe (5%), oncocytic (2%-3%), and
collecting duct or medullary (<1%) tumors. Patients with
papillary, chromophobe, and oncocytic tumors have a much
better prognosis than those with clear cell and collecting duct
tumors. Attempts have been made to diferentiate histologic
subtypes at imaging, largely based on enhanced-CT kinetics, but
overlapping patterns have precluded attempts at preoperative
imaging classiication. However, potentially relevant features may
be shown at ultrasound; for example, lack of necrosis and the
presence of calciication appear to be associated with a better
prognosis (papillary and chromophobe subtypes). 129
Before the advent of cross-sectional imaging, most patients
with RCC presented with advanced metastatic disease. In a 1971
series the classic diagnostic triad of lank pain, gross hematuria,
and palpable renal mass was seen in 4% to 9% of patients at
presentation. 130 Systemic symptoms (e.g., anorexia, weight loss)
are common with advanced disease. Manifestations reported
secondary to hormone production include erythrocytosis
(erythropoietin), hypercalcemia (parathormone, vitamin
D metabolites, prostaglandins), hypokalemia (adrenocorticotropic
hormone [ACTH]), galactorrhea (prolactin),
hypertension (renin), and gynecomastia (gonadotropin).
RCC metastases to virtually every organ in the body have been
described.
A
B
FIG. 9.45 Medullary Nephrocalcinosis in Two Patients. (A) Anderson-Carr-Randall kidney. Sagittal sonogram demonstrates increased echogenicity
in a rimlike pattern around all medullary pyramids and several punctate, shadowing calculi. (B) Sagittal sonogram shows extensive medullary calciication
in a patient with renal tubular acidosis.