Presentation
Post menopausal patient of Mediterranean origin presented for routine follow up due to past history of left-sided radical mastectomy and completed chemoradiotherapy for carcinoma breast otherwise asymptomatic. All other imaging was negative for any metastatic disease or any other significant findings.
Patient Data
There is evidence of a rounded lesion seen in the posteromedial cortex of the right kidney near the region of the hilum in the lower pole region. This lesion shows mildly hyperdense attenuation as compared to rest of the renal cortex (attenuation values in non-contrast images is 45HU, while the attenuation values of the rest of the renal cortex are approximately 30 to 35HU). The lesion is partially exophytic in nature and is causing minimal contour deformity of the renal cortex; however, peripheral interfaces appear to be maintained. It does not appear to be encroaching or compressing upon the underlying calyces.
Post-contrast images in the corticomedullary phase reveal marked contrast enhancement within this lesion with attenuation values reaching up to the level of 112HU (attenuation values of the rest of the renal cortex is in the range of 200 to 220HU). In the cortical phase (approximately 90 seconds after the contrast administration), the lesion shows a well-demarcated outline and appears hypodense as compared to rest of the enhancing renal cortex. It shows moderate washout of the contrast with attenuation values reaching up to 80HU at this phase. The lesion measures approximately 17.7mm x 18mm. The lesion shows a few subtle enhancing septa within it. No other focal lesion noted in the renal parenchyma. The renal hila appear to be normal. The renal artery shows normal enhancement. The renal vein shows normal appearance without any evidence of thrombosis. The supra-renal region is seen normally. The pelvicalyceal system shows normal appearance with normal enhancement and normal opacification seen in the excretory phase. Bilateral ureters are normal in caliber and course.
Small medullary cyst in the left kidney measuring only a few millimeters in size, located in the upper pole region of the left kidney.
Perinephric fat planes are seen normally. The supra-renal region seen normally.
Conclusion:
Right kidney reveals evidence of approximately 17.5mm x 18mm well-demarcated hyperdense lesion seen in the anteromedial cortex of the right kidney with at least partially exophytic location but with evidence of definite and significant contrast enhancement and few enhancing internal septa. The excision of the lesion is advised.
Small medullary cyst in the left kidney unlikely to be of clinical significance.
Incidental note also made of severe fatty infiltration of the liver.
Incidental note also made of cholelithiasis.
Case Discussion
Based on the CT appearance and USG appearance (which revealed an echogenic lesion) - the most important differential diagnosis was a small oncocytoma/lipid-poor angiomyolipoma. However, the possibility of RCC can not be ruled out. Since the patient has a history of left-sided breast cancer (now completely treated and patient disease-free for 5 years), although unlikely, however, the possibility of metastasis is also there. CT thorax was performed which did not reveal and metastasis. However, it is clear that this lesion needs excision.
Laparoscopic nephron-sparing resection of the right renal tumor was performed near the hilum, posterior-medial.
HPE reveals 2.5 X 1.5 X 0.6 cm tumor. The microscopic examination reveals epithelioid and spindle cells in palisades and interlacing fascicles. Thick-walled vessels with hyalinized walls present. Smooth muscles and entrapped adipose tissue present.
Tumor cells are Melanin -A positive, SMA positive, and Cytokeratin negative.
Thus a diagnosis of spindle cell tumor - consistent with angiomyolipoma.
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