Hepatic Epithelioid Angiomyolipoma: A Case Report

Hepatic epithelioid angiomyolipoma (HEAML) is a rare mesenchymal tumor belonging to the family of perivascular epithelioid cell tumors (PEComas), a group of mesenchymal neoplasms characterized by the proliferation of distinctive perivascular epithelioid cells expressing both melanocytic and smooth muscle markers. Because of its hypervascular nature and nonspecific imaging features, HEAML can closely mimic other hypervascular hepatic lesions, including hepatocellular carcinoma, hepatic adenoma, and focal nodular hyperplasia, making accurate preoperative diagnosis challenging. A 42-year-old woman was incidentally found to have a hepatic mass in the left lobe during a routine health examination. Abdominal ultrasonography revealed a relatively homogeneous hypoechoic lesion with well-defined margins and mild bulging of the liver capsule, containing thin internal echogenic strands. Magnetic resonance imaging demonstrated a mild signal drop on out-of-phase images compared with in-phase images, suggesting the presence of microscopic fat. Following contrast administration, the lesion showed strong heterogeneous arterial enhancement with punctate and linear intratumoral vessels, followed by prolonged enhancement in the portal venous and delayed phases ("wash-in, slow-out"). Early enhancement of a draining vein connected to the left portal vein branch was also observed. The patient underwent surgical resection. Histopathological examination revealed epithelioid cells with clear cytoplasm arranged around thin-walled blood vessels, without necrosis or significant mitotic activity. Immunohistochemical analysis showed positivity for HMB45, Melan-A, and smooth muscle actin, and negativity for HepPar-1, cytokeratin, and CD117, confirming the diagnosis of HEAML. HEAML is a rare hepatic tumor in which the integration of imaging findings and immunohistochemical analysis is essential for achieving an accurate diagnosis and guiding appropriate clinical management.