[916] Renal Translocation t(6;11) Carcinoma: A Study on 5 Cases Using Histomorphology, Immunohistochemistry, Ultrastructure and Molecular Genetic Techniques.

Fredrik B Petersson, Tomas Vanecek, Michal Michal, Guido Martignoni, Matteo Brunelli, Dominic Spagnolo, Naoto Kuroda, Ximing Yang, Isabel Alvarado Cabrero, Milan Hora, Ondrej Hes. Charles University and University Hospital, Plzen, Czech Republic; National University Health System, Singapore, Singapore; University of Verona, Italy; PathWest Laboratory Medicine WA, Nedlands, Australia; Red Cross Hospital, Kochi, Japan; North West University Chicago, IL; Centro Medico, Mexico City, Mexico

Background: To date, only few cases of “rosette forming t(6;11), HMB45 positive renal carcinoma” have been published. In this paper we contribute further data on 5 cases.
Design: All cases were examined histologically and immunohistochemically. In 3 cases ultrastructural studies were performed. Molecular genetic studies using aCGH, RT- PCR and FISH were employed on 3 cases where fresh tissue was available.
Results: Patients were 4 females and 1 male, age range 20 to 39 years. Follow up (range 3-5 years) did not reveal any metastatic events or recurrences. All tumors were mostly encapsulated. No necrosis was seen. Tumors displayed a solid or solid/alveolar architecture and contained (occasionally long and branching) tubular structures composed of dyscohesive neoplastic cells and, more frequently, pseudorosettes. 5/5 cases displayed focal immunoreactivity for HMB-45, Cathepsin K. Melan A and MiTF was positive in 3/5 cases, respectively. Tyrosinase and vimentin positivity was found in 4/4 cases, respectively. Cytokeratins and CD10 were positive in 4/5 cases, respectively. On ultrastructural examination, numerous electron-dense secretory granules resembling melanosomes were present in the cytoplasm. Psedorosettes were composed of reduplicated basement membrane-like material. aCGH revealed multiple chromosomal changes, especially losses. In 2/3 cases there was loss of chromosome 22. Using RT-PCR, 2/3 tumors were positive for theAlpha -TFEB-fusion transript. No VHL mutation, LOH 3p, or promotor methylation of the VHL gene was found in 2 cases studied.
Conclusions: 1, “rosette forming t(6;11), HMB45 positive renal carcinoma” displays some morphologic heterogenity, e.g. characteristic pseudorosettes are not always conspicuous. 2, Immunoreactivity for HMB-45 (but not Melan A or MitF) and Cathepsin K appears to be constant finding and expression of cytokeratins is a frequent finding. 3, Loss of chromosome 22 was the most common numerical aberration, no mutation of the VHL-gene or LOH 3p were present. 4, All cases appear to pursue a benign clinical course.
Category: Genitourinary (including renal tumors)

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 102, Wednesday Morning

 

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