Hepatic PEComa, a rare cause of a liver mass

Perivascular epithelioid cell tumors (PEComas) are rare mesenchymal neoplasms characterized by the coexistence of melanocytic and smooth muscle differentiation, with hepatic involvement being exceptionally uncommon. We present the case of a 60-year-old man with no relevant past medical history, who presented with right upper quadrant pain, without constitutional symptoms or significant laboratory abnormalities. Abdominal ultrasound revealed a hepatic mass in the right lobe. Further evaluation with contrast-enhanced computed tomography and dynamic liver magnetic resonance imaging demonstrated a hypervascular lesion in segments VI-VII, with imaging features suggestive of malignancy. The main differential diagnosis considered was mass-forming intrahepatic cholangiocarcinoma. Tumor markers, including alpha-fetoprotein and CA 19-9, were within normal limits. Given the diagnostic uncertainty, a percutaneous liver biopsy was performed. Histopathological and immunohistochemical analysis showed a mesenchymal proliferation with a myomelanocytic immunophenotype, with co-expression of HMB-45 and smooth muscle actin, consistent with hepatic PEComa. Following multidisciplinary team discussion, surgical treatment was decided. This case highlights the importance of considering hepatic PEComa in the differential diagnosis of hypervascular liver masses, particularly when presenting as a solitary lesion in a non-cirrhotic liver and with normal tumor markers.