Cytohistomorphological Features of Primary Renal Leiomyosarcoma: A Rare Case Report

Primary sarcomas of the kidney are extremely rare tumor in adults accounting for about 1% of all tumours. The most common type is leiomyosarcoma (40%) followed by pleomorphic sarcoma, hemangiopericytoma, fibrosarcoma and unclassified sarcoma. Primary renal leiomyosarcoma is thought to originate from the smooth muscle cells of the renal pelvis, renal capsule or the renal vessels. A 51-year-old female presented with abdominal pain and swelling in left flank. On systemic examination abdomen was soft, non-tender with a palpable mass of size 8*6 cm in left flank. CECT revealed a lobulated exophytic enhancing soft tissue mass lesion in left lumbar region abutting the lower pole of left kidney, left renal vessels and left pelviureteric junction provisional diagnosis of renal cell carcinoma. FNA smears showed clusters, bundles and fascicles of plump round to oval to spindle shaped cells with focal storiform pattern. Diagnosis of a retroperitoneal sarcomatoid lesion was made with differential diagnosis of Leiomyosarcoma, synovial sarcoma and sarcomatoid carcinoma. Histopathological examination and immunohistochemistry confirmed the diagnosis of leiomyosarcoma of kidney. Radiological investigations are not helpful in differentiating leiomyosarcomas from other renal carcinomas. Cytological smears show predominantly atypical spindle cells. Histopathology and immunohistochemistry are mainstay for diagnosis. Keywords: Kidney, cytology, histopathology, sarcoma, immunohistochemistry