[899] Mixed Epithelial and Stromal Tumor of Kidney. Molecular and IHC Findings of a Possible New Hereditary Syndrome

Lai Jin-Ping, Beatriz A Walter Rodriguez, Phyu P Aung, Marston Linehan, Maria J Merino. NCI,NIH, Bethesda; NCI, NIH, Bethesda

Background: Mixed epithelial and stromal tumor (MEST) of the kidney is a rare renal tumor occurring predominantly in perimenopausal women. Recently it has been postulated that MEST and Cystic nephroma represent variants of the same process because their morphological and molecular characteristics. We report five new cases of kidney MEST and describe the occurrence of these tumors in a familial setting.
Design: Five cases of MEST including 2 familial tumors and 3 sporadic were studied. Tumors were immunohistochemically evaluated for ER, PR, SMA, Desmin, CA-125, Her2, calretinin, bcl-2, CD99, pax-8 and Ny-eso-1 antibodies. Protein expression of the DICER1 gene encoding an endoribonuclease was also performed. The presence of t(x;18) (p11.2;q11) translocation for human synovial sarcoma was investigated by RT-PCR. For loss of heterozygosity (LOH) analysis of the 3p12-3p21 region, tumor and normal kidney areas were microdissected and the DNA extracted. Comparative genomic hybridization (CGH) was also done to evaluate presence of genetic gain or losses in the MEST.
Results: The familial tumors occur in a 75-year old man with bilateral renal masses with similar morphologic features, and in his two daughters. One daughter is 47 years old and had a 3 cm renal mass, morphologically similar to the father's. The sister has a cystic renal mass and will undergo surgery. The three sporadic cases were all female aged 36, 40 and 52 years. Morphologically, the tumors were well circumscribed and varied in size, cystic component, and amount and cellularity of stroma. By IHC, ER, PR, SMA and Desmin were positive in the stromal cells for all five cases. Pax-8 was positive in the epithelial component. Calretinin showed focally positivity in both epithelial and stromal cells. CA-125 and Her2 were negative. One sporadic case, showed dense cellular spindle cell proliferation. Immunostain was positive for Bcl-2 and CD99. However, there was no evidence of the t(x;18) (p11.2;q11) translocation by RT-PCR. LOH for VHL markers (3p-3p21 loci) (D3S1038, D3S1110, D3S1597, D3S1317, D3S1560) was performed in all the cases but there were negative. CGH analysis also yield negative results for large areas of gain or losses. All patients have remained free of disease.
Conclusions: We conclude that Mixed Epithelial and Stromal Tumor of the kidney are neoplasms with excellent prognosis that can occur in a familial and hereditary setting. The histological and molecular profile for the hereditary and sporadic cases are similar.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 11:15 AM

Platform Session: Section A, Monday Morning


Close Window