BAP1 and lymphangioma: Studies have shown that MCPM biopsies are positive for a series of markers such as the proliferative protein Ki-67 [21], cytokeratin 5/6, calretinin, BAP1, the transcription factor WT-1, and negative for endothelial markers (CD 31, CD 34, and factor VIII) [22] whereas the opposite is true for lymphangioma.