Retroperitoneal Cystic Adenopecoma with Genetic Analysis: A Rare Neoplasm.

Lymphangiomyomatosis is a member of the PEComa family, and usually involves the pulmonary parenchyma of middle-aged females. Infrequently, it may involve abdominal and retroperitoneal lymph nodes, and rarely it has been described to be associated with fallopian tube-type ciliated epithelium co-existing in one neoplasm. To increase our understanding of this unusual tumor, we describe the morphology and genetics of one case and review the literature. We present the case of a 50-year-old female found to have 12.5 and 7.7 cm cystic retroperitoneal masses, describe its unique pathological features and review the literature on the previously reported cases. Based on its unique morphological, immunohistochemical, and molecular features we propose the term adenoPEComa to represent this entity. This case represents a rare example of adenoPEComa with lymphangiomyomatosis of the lymph nodes. It is the first example that has undergone next-generation sequencing revealing a mutation in TSC2 making it a confirmed member of the PEComa family of tumors.