[941] Clear Cell Tubulopapillary Renal Cell Carcinoma (CCTPRCC): A Further Distinction from Other Renal Epithelial Tumors

Bhuvaneswari Krishnan, Luan D Truong, Steven S Shen. Michael E. DeBakey VA Medical Center, Houston, TX; Baylor College of Medicine, Houston, TX; Methodist Hospital, Houston, TX

Background: CCTPRCC is a recently described renal epithelial neoplasm seen in both normal and end-stage kidneys. Its immunohistochemical and molecular studies show features not shared by clear-cell or papillary RCC.
Design: Kidney tumors resected at our institutions were reviewed for tumors showing histological features of CCTPRCC. These tumors were then further analyzed. Immunohistochemical stains including pancytokeratin (AE1/AE3), cytokeratin (CK) 7, vimentin, CD10, RCC Marker, high molecular weight (HMW) CK, AMACR, and Kidney-specific cadherin (KSP) were performed. The gross photographs when available were reviewed. The clinical information and pathological findings were analyzed.
Results: Sixteen tumors from12 patients showed the histological features suggestive of CCTPRCC. There were 8 males and 4 females, between 36 to 80 years, (average 62 years). Three tumors were in end stage kidney. Four patients, ages 61-67 years without a family history of renal tumors, had multiple tumors in normal kidneys, two of which were also bilateral. The gross photographs in two cases of multifocal tumors, showed circumscribed tumors with brown, solid and cystic areas. Histologically, all tumors were in the cortex and showed a papillary and tubular architecture with low nuclear grade, absence of necrosis, foam cells, calcification or the delicate network of vessels. The Immunohistochemical stain showed diffuse strong positivity for panCK, CK7, HMWCK, and vimentin. KSP was focally positive in six cases. CD10, RCC Marker and AMACR were negative. All tumors were staged T1a/T1b. Renal tumors other than CCTPRCC were noted in two cases with multiple tumors (multiple papillary RCC and multiple hybrid oncocytic tumors in a patient with Birt-Hogg-Dube syndrome). There was no metastasis in 8-72 months follow-up of all patients.
Conclusions: CCTPRCC is a distinct tumor with typical gross, microscopic and immunohistochemical features. The immunohistochemical features suggest a distal tubule/collecting duct origin, distinct from clear cell or papillary RCC. The positivity for HMWCK, CK 7 and negativity for RCC marker and AMACR is helpful in differential diagnosis from clear cell and papillary RCC even on core biopsies. It is a low-grade tumor without evidence of metastasis. It can be associated with other epithelial tumors including papillary RCC and oncocytic neoplasms.
Category: Genitourinary (including renal tumors)

Tuesday, March 5, 2013 1:00 PM

Poster Session IV # 194, Tuesday Afternoon


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