[846] Intracystic Oncocytic Papillary Renal Neoplasms: A Variant of Epithelial Papillary Neoplasms Distinct from Papillary Renal Cell Carcinoma

H Faraji, KT Mai. University of Ottawa, Ottawa General Hospital, Ottawa, Canada

Background: We described 6 intracystic oncocytic papillary renal cell carcinoma (IOPRCC) that were histopathologically and cytogenetically distinct from the common chromophil (papillary) renal cell carcinoma (PRCC).
Design: IOPRCC were identified the Anatomical files at our institution and were further characterized with immunostaining for AMACR, CK7 and fluorescent in situ hybridization (FISH) for chromosomes 7, 17, Y and 3p (loci 3p14 and 3p25).
Results: Of the total of 659 renal cell carcinoma (RCC), there were 6 IOPRCC, measuring 1.5 to 6 cm (2.4±1.1) occurring in patients with male: female ratio of 5:1 and ages of 46-73 years (57± 8). All tumors were not associated with distant metastasis or local recurrence in a period of follow-up from 1 to 12 years. The IOPRCC consisted of oncocytic /eosinophilic cells forming characteristic papillae sparsely arranged and non-papillary architecture within the unilocular cysts. In 4 tumors, the neoplastic cells accounted for 30-50% of the cystic volume. The remaining two tumors displayed similar features in focal areas but occupied almost the entire cysts. The tumors displayed extensive foamy cytoplasm with or without focal clear cell changes in 4 cases. Capsular invasion was present in one case. Immunostaning was negative for progesterone receptor, cytokeratin 7, CD117 and carbonic anhydrase IX and positive for alpha-methylacyl-CoA racemase, vimentin, CD10 and RCC. FISH revealed no loss of chromosome 3p in all tumors and Y in all male patients and no trisomies of 7/17 in five tumors. One tumor (6 cm in diameter) showed trisomies 7/17 in focal areas.
Conclusions: IOPRCC is a distinct variant of RCC due to the favourable clinical behaviour, the intracystic proliferation of sparsely arranged oncocytic papillae and the absence of chromosomal numeric changes of PRCC.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 140, Tuesday Morning


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