CD99 and skin cancer: It is interesting that both MCC types have similar phenotypes, and several tissue markers were detected in skin cancer that may be positive or not for MCPyV, including apoptosis regulator B-cell lymphoma-2 (BCL2), cytokeratin 20, neural cell adhesion molecule 1, CD99, CD99 antigen, epithelial cell adhesion molecule, huntingtin-interacting protein 1, neuron-specific enolase, and neurogenic locus notch homologue protein 1.