[781] De-Differentiated Tubulocystic Carcinoma of the Kidney: A Series of 3 Cases with FISH Analysis

Turki Al-Hussain, Liang Cheng, Shaobo Zhang, Jonathan I Epstein. The Johns Hopkins Hospital, Baltimore; Indiana University School of Medicine, Indianapolis

Background: Tubulocystic renal cell carcinoma (RCC) is relatively rare and was first described as a low grade variant of collecting duct carcinoma. This variant was not recognized in the 2004 WHO classification and only received its current name in 2009 in a series of 39 cases from 7 large institutions. It is low grade with only 2/17 cases with follow-up in this prior series developing metastases. Its relationship to collecting duct carcinoma is controversial and recent studies have linked it with papillary RCC. Only 1 case from 2011 describes a sarcomatoid tubulocystic RCC.
Design: 3 consult cases of de-differentiated tubulocystic RCC were identified. FISH was performed on 2 cases with available material.
Results: Two lesions measuring 9.5 cm. and 3.8 cm. were described as partly solid and cystic. One case was grossly a 14.0 cm cyst with a granular lining. Microscopically, all had classic areas of circumscribed tubulocystic RCC occupying 30%, 80%, and 90% of the tumor. 2 cases had small components of papillary RCC and 1 case a central large cystic component. In 2 cases, a proliferation of small tubules infiltrated away from the main mass with typical features of collecting duct carcinoma. In the 3^rd case, a focus of sarcomatoid carcinoma was seen adjacent to the tubulocystic RCC. In 2 cases, tumor invaded peri-renal tissue. The 3^rd case was organ confined with vascular invasion. 1 patient died 9 months post-operatively with metastases to the abdominal wall and femur. The 2^nd case developed metastases to retroperitoneal nodes 3 years post-operatively. The 3^rd patient was lost to follow-up.

Tumor Pattern	Chromosome 7	Chromosome 17	Chromosome Y
Case 1. Tubulocystic	Disomy	Trisomy	Loss
Case 1. De-differentiated	Disomy	Trisomy	Disomy
Case 2. Tubulocystic	Disomy	Trisomy	Disomy
Case 2. De-differentiated	Disomy	Trisomy	Disomy

Conclusions: This is the first series and only the 2nd report of de-differentiated tubulocystic RCC. FISH results showed some features that are seen with papillary RCC in both the tubulocystic and dedifferentiated components and with one exception showed identical cytogenetic findings between the 2 components. Morphologically, in 2 cases the de-differentiated areas were also indistinguishable from collecting duct carcinoma suggesting a relationship between the 2 entities. De-differentiated tubulocystic RCC increases the risk of aggressive behavior above that of usual tubulocystic RCC.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 88, Wednesday Morning