Renal Cell Carcinoma With (Angio)Leiomyomatous Stroma in a Patient With TSC2 Mutation: A Case Report

Abstract

Abstract We present the case of a 34-year-old woman with a TSC2 gene mutation diagnosed with 4 distinct renal cell carcinomas with (angio)leiomyomatous stroma and 2 concomitant angiomyolipomas of the left kidney. Histologically, the nodules, located in the renal cortex, were mostly encapsulated with an abundant smooth muscle stromal component, which delved into the central epithelial component of the tumor forming septations. The epithelial component was made up of elongated tubules, papillae, and acinar structures with clear to eosinophilic cytoplasm and apical snouts. Focal acinar structures were filled with hypereosinophilic material. The nuclei were basally located and supported by a delicate vascular network. Immunohistochemical studies revealed the tumor cells to express cytokeratin 7, CD10 variably, and carbonic anhydrase IX in an incomplete “cup-like” membranous pattern. The tumor cells did not express AMACR, TFE3, MART-1, or cathepsin K. This report describes a unique presentation of a rare entity and brings attention to an evolving diagnostic field. We discuss problems and controversy surrounding the diagnosis of renal cell carcinoma with (angio)leiomyomatous stroma, its relationship to clear cell papillary renal cell carcinoma and other tumors, and how it correlates with newly discovered genetic mutations.