[1776] Xp11.2 Translocation Renal Carcinomas in a Pediatric Population

J Hicks, K Eldin, E Wartchow, G Mierau. Texas Children's Hospital, Baylor College of Medicine, Houston, TX; The Children's Hospital, Denver, CO

Background: Xp11.2 translocation renal cell carcinomas (RCC) demonstrate TFE3 (Xp11.2) fusion with several different partners (ASPL, 17q25; PRCC, 1q21; PSF, 1p34; NonO, inv(X)p11.2;q12); CLTC, 17q23). These tumors tend to occur in children and young adults. Xp11.2 tumors account for up to 75% of all RCCs in pediatrics. TFE3 immunostaining is available to distinguish these tumors from conventional RCCs, in addition to cytogenetic/molecular studies. Electron microscopy (EM) may be helpful in identifying a subset of Xp11.2 tumors with an ASPL fusion partner, which have crystalline rhombiod strucutures identical to those in alveolar soft part sarcoma.
Design: 6 TFE3-positive RCCs had tissue available for routine, immunocytochemistry (ICC)and EM study (3M:3F, age range 4 to16yrs). ICC for pancytokeratin, EMA, vimentin, RCC, CD10, TFE3 and HMB45 was performed. EM was performed on glutaraldehyde-fixed tissue in 3 cases and on paraffin-recovered tissue in 3 cases. Cytogenetic analysis was available in 4 cases.
Results: Tumor size ranged from 1 to 13cm. Tumor was confined to the kidney in 2 cases. Renal vein was involved in 3 cases. Metastatic disease was present in 4 cases (lymph nodes, lung, liver, retroperitoneum). Tumors tended to have pseudopapillary architecture comprised of clear cells with voluminous cytoplasm and thick, plant-like cell borders. Fuhrman nuclear grade 3 was typical. Occasional deeply eosinophilic cytoplasm was seen. Extracellular eosinophilic basement membrane-like material was seen infrequently. ICC demonstrated: nuclear TFE3 (6/6), RCC (6/6), CD10 (5/6), vimentin (0/6), pancytokeratin (0/6), EMA (0/6) and HMB-45 (0/6). EM showed abundant glycogen, intercellular desmosome-like junctions, lipid inclusions and basement membranes. Infrequent rhomboid crystalline structures were found in 2 cases. Cytogenetics was performed in 4 cases and detected Xp11.2 translocations (ASPL-TFE3 [2/4]; PSF-TFE3 [1/4]; PRCC-TFE3 [1-4]).
Conclusions: Xp11.2 RCCs are unique renal neoplasms that primarily occur in the pediatric population. At initial diagnosis, these tumors tend to present at advanced stages with locoregional and distant metastatic disease. Complete resection of the primary renal mass and metastases with adjuvant therapy when indicated provide a favorable overall survival rate (92% 5-yr survival AJCP 2006;126:349-64). Immunocytochemical, electron microscopic and cytogenetic/molecular diagnostic techniques utilized in concert allow for an accurate diagnosis and appropriate therapy.
Category: Ultrastructural

Monday, March 9, 2009 1:00 PM

Poster Session II # 247, Monday Afternoon