[907] Clear Cell Papillary Renal Cell Carcinoma. A Histological Study of 12 Cases in Patients under 40 Years of Age

JI Lopez, I Anton, JM Onate, H Garcia-Munoz. Hospital de Cruces, University of the Basque Country (UPV/EHU), Barakaldo, Bizkaia, Spain; POVISA, Vigo, Pontevedra, Spain; Hospital del Rio Hortega, Valladolid, Spain; Hospital 12 de Octubre, Complutensis University, Madrid, Spain

Background: Clear cell papillary renal cell carcinoma (CCPRCC) is a recently described but not yet well defined entity within the histological spectrum of renal tumours. Its real incidence is unknown because some cases may have been included within other well known histological subtypes of renal cancer. Only single cases have been reported so far in young patients. Our aim in this study was to delineate the light and immunohistochemical profile of CCPRCC in young patients.
Design: A total of 130 renal cell carcinomas in young patients (<40 year old) were collected in a multicenter study in Spain. Among them, 12 (9.2%) cases fulfilled the histological criteria of CCPRCC (Gobbo et al., AJSP 32: 1239, 2008). An immunohistochemical study using CD10, EMA, CK7, CK20, CD15, CD117, AMACR, Cam 5.2, 34betaE12, e-cadherin, Melan-A and TFE-3 was performed and the results compared with those obtained in the whole series.
Results: Males predominated in the series (10M/2F) with an average age of 33.6 years (range, 23-39). Mean tumour diameter was 6.3 cm. Overall, 83.3% were organ confined tumours. Low nuclear grade (Fuhrman) predominated in the series (G1, 5 cases; G2, 6 cases; G3, 1 case). Concurrent metanephric adenoma was found in one case. No significant differences were observed in terms of age, sex, tumour diameter and tumour staging when compared CCPRCCs with the rest. Immunostaining with CD10 (9 cases, 75%), EMA (9 cases, 75%), Cam 5.2 (9 cases, 75%) and AMACR (8 cases, 66.6%) was the most commonly found pattern in these tumours. CK7 and e-cadherin were less commonly found, being positive in 5 (41.6%) and 3 (25%) cases, respectively. AMACR distinguished CCPRCCs from conventional clear cell renal cell carcinomas [χ2, p=.000, Relative Risk=6.07, CI (95%)=1.98-18.64]. CD117, CK20, 34βE12, Melan-A and TFE-3 were negative in all cases.
Conclusions: CCPRCC is a quite common renal tumour subtype in patients under the age of 40. A high percentage of these tumours show low grade features and organ confined disease at diagnosis. Distinct light and immunohistochemical features allow the recognition of CCPRCC in routine practice.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 157, Tuesday Morning


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