Type: Term Definitions: 1. A group of mesenchymal tumors composed of epithelioid and spindle cells displaying perivascular epithelioid (PEC) differentiation. The PEComa family of tumors includes angiomyolipoma, clear-cell 'sugar' tumor of lung and gastrointestinal tract and other sites, lymphangioleimyomatosis, clear-cell myomelanocytic tumor of th...