[918] Smooth Muscle Rich, Tubulo-Cystic Papillary Renal Cell Carcinoma. A New Renal Tumor? Immunohistochemical and Genetic Characteristics

MJ Merino, L Jinping, K Killian, M Linehan. NCI, Bethesda, MD

Background: While the majority of renal tumors occur sporadically, the true incidence of hereditary tumors is not exactly known. It is possible that the incidence is higher than the predicted 5%, since it is only now that considerable insight into the genetic basis of renal cancer is available. Proliferation of smooth muscle cells and lymphatic vessels has been described in the kidney as lymphangioleiomyomatosis and angiomyoleiomas that occur in the Tuberous sclerosis complex. We studied six unusual cases of smooth muscle rich renal cell carcinoma and describe their morphological, immunohistochemical and genetic changes.
Design: Six patients with multifocal and bilateral renal tumors, were evaluated for protocol acceptance. Tumors were morphologically and immunohistochemically evaluated. Tissue was microdissected and DNA obtained for CGH and LOH analysis of multiple genes.
Results: Patients ranged in age from 35-79 years. Five patients were males and 1 was female. Multiple tumors were removed from each patient varying in size from 4-0.8 cm. Grossly they had a tan to light yellow color. Histologically, there were composed of solid and diffuse clusters of clear tubules surrounded by smaller tubules with less cytoplasm and occluded lumen, that gave the appearance of mantles. The tubules had a centrally located indolent nucleous. These nests were surrounded by muscle and collagenous fibers. Cysts and malformed papillae with abundant muscle in the stall were also present. In areas the muscle and fibrous proliferations were prominent. IHC was performed for CK7, CK20, CAM5.2, EMA, CD10, CD56, SMA, Collagen IV, Calponin, Vimentin, S-100 and HMB45. CGH analysis did not reveal significant changes in the VHL or BHD genes.
Conclusions: We report an unusual group of renal cell tumors with prominent proliferation of smooth muscle and tubular, cystic and papillary elements. The tumors are low grade and stain strongly with CK7 and SMA. It is possible that these tumors represent new entities or unsuspected variants on known syndromes. Recognition of these neoplasms will allow for identification of new and specific genes, that will lead to the development of specific molecular targets.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 162, Tuesday Morning


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