Clinical History:
A 33-year-old female patient transferred for the further evaluation of a
renal mass with a one month history of right flank pain.
Figure 1a |
Figure 1b |
Figure 1c |
Radiographic Findings:
Non-enhanced CT (Fig 1a) shows a round mass in the upper pole of the right
kidney (arrows). CT number of the mass (40 HU) is slightly higher than renal
parenchyma (30 HU). The mass shows homogeneous enhancement (66 HU) in the
arterial phase (Fig 1b) and progressive enhancement (103 HU) in the delayed
phase (Fig 1c).
Discussion:
Radiologic Differential Diagnosis
- Renal cell carcinoma.
- Benign renal tumor such as an angiomyolipoma.
Renal adenoma is an uncommon benign renal tumor. It has been described
in the pathology literature as a solid mass of variable size, occurring
more commonly in young women, and sometimes associated with polycythemia
(1). There is a debate over its benign or malignant nature. Some classify
adenomas as adenocarcinoma if the diameter is larger than 3 cm, even though
the cells are benign and identical in all respects to those of smaller
lesions (2). Due to the broad range of biological behaviors seen in lesions
assigned a microscopic diagnosis of adenoma, many pathologists classify
all of renal adenoma as low-grade adenocarcinoma. The radiological literature
has postulated that metanephric adenoma has high attenuation relative
to the adjacent renal parenchyma on unenhanced CT because of psammomatous
calcification and shows some enhancement and lower attenuation compared
with the adjacent parenchyma on enhanced CT (2).
Diagnosis:
References:
- Davidson AJ, Hartman DS, Choyke PL, Wagner BJ.
Diagnostic set: large, unifocal, unilateral. In: Radiology of the kidney
and genitourinary tract. 3rd ed. Philadelphia, Saunders, 1999:269-270.
- Fielding JR, Visweswaran A, Silverman SG, Granter SR,
Renshaw AA. CT
and ultrasound features of metanephric adenoma in adults with pathologic
correlation. J Comput Assist Tomogr 1999;23:441-444.
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