Pigmented perivascular epithelioid cell tumor of the liver: report of a rare case with brief review of literature.

The perivascular epithelioid cell tumor (PEComa) family of tumors includes angiomyolipoma, lymphangioleiomyomatosis, clear cell sugar tumor of the lung, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, and rare clear cell tumors of other anatomical sites (PEComas-NOS). Among the PEComas-NOS, pigmented variants are extremely rare. The case concerns a 50-year-old female who presented with pain in right hypochondrium. The resected specimen included a 24 × 18 × 9 cm mass. The tumor was histologically characterized by both spindle and epithelioid cells with round to oval nuclei and clear to eosinophilic cytoplasm containing abundant melanin pigment. The stroma demonstrated intervening, thin, fibrovascular septa. Immunohistochemically, the tumor cells were strongly positive for HMB-45, weak positive for smooth muscle actin (SMA), and negative for Hep Par 1, Glypican 3, MUM-1, and S-100 protein. The patient had no evidence of disease 24 months after surgery. Pathologists and clinicians should know about the existence of pigmented perivascular epithelioid cell tumor of the liver.