Renal capsular PEComa––a rare cause of surgically correctable renal hypertension

Abstract

We report a 40-year-old lady who presented with severe headaches, persistent microscopic haematuria and hypertension requiring anti-hypertensive medication. Investigations for secondary hypertension were all normal except for a CT scan. This indicated a complex cystic lesion, measuring 2.4 x 5 x 10 cms , arising from the right kidney. She underwent an open right partial nephrectomy. The patient made an un-eventful postoperative recovery and her blood pressure returned to normal. The mass had a smooth outer surface and the cut surface showed firm whitish tissue with a few small cysts. Microscopy showed a bland spindle cell lesion staining positively for SMA, desmin, caldesmon, focally for HMB45 amd very focally for S100. The mass was reported as a Perivascular Epitheloid Cell (PEC) lesion (PEComa) arising from the renal capsule. Perivascular Epitheloid Cell tumor (PEComa), a recently defined tumor, is extremely rare. The lesion presents a distinct muscular immunophenotype (actin+, desmin+), with co-expression of the melanogenesis marker (HMB45). This combined immunophenotype is a characteristic feature of the Perivascular Epitheloid Cell (PEC) lesions. PEComa's are usually benign, but cases have been reported in the literature which has an unfavourable outcome with metastatic dissemination. We report this case because of its rarity and also Renal Capsular PEComa should be considered as a rare cause of renal hypertension, which can be surgically cured.