[919] Primary Leiomyosarcoma of the Kidney: A Clinicopathologic Study of 27 Cases

JS Miller, M Zhou, F Brimo, CC Guo, JI Epstein. Johns Hopkins Hospital, Baltimore; Cleveland Clinic, Cleveland; MD Anderson Cancer Center, Houston

Background: Primary leiomyosarcoma of the kidney is a rare entity that has not been well-characterized.
Design: We retrieved 27 cases of primary renal leiomyosarcomas diagnosed at three institutions between 1986 and 2009. Any evidence of a carcinomatous component, either histologically or immunohistochemically, indicated the diagnosis of the more-common sarcomatoid carcinoma (carcinosarcoma) and led to the case's exclusion from the study. Cases with leiomyosarcomas secondarily involving the kidney (e.g. retroperitoneal leiomyosarcomas) were also excluded based on radiologic, operative, and/or pathologic findings.
Results: Mean patient age at diagnosis was 58.5 years (range 22 to 85) and 59% were female. Mean tumor size was 13.4 cm (range 4 to 26) and 59% of the tumors were identified in the right kidney. Detailed histologic examination was possible for 24 of the cases. Average mitotic count per ten high power fields was 11.1 (range 0 to 50) and the average extent of necrosis was 21% (range 0 to 60). Cellular pleomorphism was classified as either focal (n=13) or extensive (n=11) and graded as mild (n=3), moderate (n=7), or severe (n=14). Tumors were either grade 2 (n=12) or grade 3 (n=12) using the French Federation of Cancer Centers System. Direct extension beyond the kidney capsule was identified in 55% of the cases, and lymphovascular invasion was identified in 26%. Clinical follow-up information was available for 20 of the cases, and patients were followed for an average of 2.8 years (range 0.25 to 9). Distant metastases were identified in 90% of the patients, and 75% eventually died from their tumor burden. No correlation was identified between histologic features and clinical progression; virtually all of the patients in this study had a poor clinical outcome regardless of morphologic features.
Conclusions: Primary renal leiomyosarcomas have a grim prognosis regardless of the underlying histology.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 8:45 AM

Platform Session: Section A, Tuesday Morning


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