A misleading hepatic tumour: epithelioid angiomyolipoma.

Hepatic angiomyolipoma (HAML) is a rare, benign mesenchymal neoplasm composed of varying amounts of smooth muscle cells, adipose tissue, and vessels. Its morphological diversity often poses diagnostic problems. In this paper, the authors report a peculiar case of epithelioid HAML mimicking histologically hepatocellular carcinoma with focal areas resembling inflammatory pseudotumour. A 57 year-old male patient presented with abdominal pain and discomfort. Non enhanced CT scan demonstrated a heterogeneous hypodense mass located in segment II and IV of the liver. Hepatocellular carcinoma was suspected and the patient underwent left lobectomy. Histologically, the tumour was mainly composed of epithelioid cells arranged in trabeculae and sheets (50% of the tumour surface) admixed with mature fat cells (20%) and thick-walled blood vessels. Lymphocytic aggregates and clusters of foamy histiocytes were focally found in the stroma (30%). Most of the epithelioid tumour cells were immunoreactive to homatropine methylbromide 45 (HMB-45) and smooth muscle actin. Morphological pattern and immunophenotype were consistent with epithelioid HAML.