Lipid poor renal angiomyolipoma
Post menopausal patient of Mediterranean origin presented for routine follow up due to past history of left sided radical mastectomy and completed chemo radiotherapy for carcinoma breast. Patient is asymptomatic and rest of the imaging was negative for any metastatic disease or any other significant findings.
CT urography study
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There is evidence of a rounded lesion seen in the postereo-medial 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 is 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 upto 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 second after the contrast administration), the lesion shows 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 upto 80HU at this phase. The lesion measures approximately 17.7mm x 18mm. The lesion shows few subtle enhancing septa within it. No other focal lesion noted in the renal parenchyma. The renal hila appears to be normal. The renal artery shows normal enhancement. The renal vein shows normal appearance without any evidence of thrombosis. Supra-renal region is seen normally. Pelvicalyceal system shows normal appearance with normal enhancement and normal opacification seen in the excretory phase. Bilateral ureters are normal in caliber and course.
Note is also made of a small medullary cyst in the left kidney measuring only few millimeter in size, located in the upper pole region of the left kidney.
Perinephric fat planes are seen normally. Supra-renal region seen normally.
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.
Incidental note also made of a small medullary cyst in the left kidney unlikely to be of clinical significant.
Incidental note also made of severe fatty infiltration of the liver.
Incidental note also made of cholelithiasis.
Based on the CT appearance and USG appearance (which revealed and echogenic lesion)- most important d/d were a small Oncocytoma/ Lipid poor Angiomyolipoma . However, possibility of RCC can not be ruled out. Since patient has history of left sided breast cancer (now completely treated and patient disease free for 5 years), although unlikely , however, 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.
Laproscopic Nephron sparing resection of the right renal tumor performed- site near hilum- posterio-medial.
HPE reveals 2.5 X 1.5 X 0.6 cm tumor. The microscopic examination reveals epitheloid and spindle cells in pallisades 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.
- 1. Milner J, McNeil B, Alioto J et-al. Fat poor renal angiomyolipoma: patient, computerized tomography and histological findings. J. Urol. 2006;176 (3): 905-9. doi:10.1016/j.juro.2006.04.016 - Pubmed citation
- 2. Sherman JL, Hartman DS, Friedman AC et-al. Angiomyolipoma: computed tomographic-pathologic correlation of 17 cases. AJR Am J Roentgenol. 1981;137 (6): 1221-6. doi:10.2214/ajr.137.6.1221 - Pubmed citation