Retroperitoneal lymphangioleiomyoma with lymph node involvement: A pathologic-radiologic correlation of a rare form of myomelanocytic tumor.

Lymphangioleiomyomatosis (LAM) is a rare and slowly progressive disorder that usually arises in the lung, affects exclusively women in their childbearing years, and typically presents with progressive dyspnea on exertion and pneumothorax. Infrequently, extra-pulmonary LAM can occur in the retroperitoneum, uterine wall, mediastinum and intraperitoneal lymph nodes. Histologically, LAM is characterized by a proliferation of perivascular epithelioid cells (PEC) that express markers for both melanocytes and smooth muscle cells. We report a case of a peripancreatic retroperitoneal mass that was incidentally discovered on magnetic resonance image (MRI) scan of a 38-year-old female. The morphologic findings and the immunohistochemical staining were consistent with a lymphangioleiomyoma. The radiologic and pathologic correlation along with differential diagnosis of this rare entity is discussed.