Early B-Cell Differentiation in Merkel Cell Carcinomas: Clues to Cellular Ancestry

摘要: Merkel cell carcinoma (MCC) is a highly malignant neuroendocrine nonmelanoma skin cancer, which associated with the polyoma virus (MCPyV). Recently, expression of terminal deoxynucleotidyl transferase (TdT) and paired box gene 5 (PAX 5) has been consistently reported in majority MCCs. We tested 21 MCCs for MCPyV, TdT, PAX5, IgG, IgM, IgA, kappa, lambda by immunohistochemistry assessed IgH Igk rearrangement all All revealed specific PAX5 72.8% expressed TdT. In addition, most one or more Ig subclasses kappa lambda. One MCC did reveal monoclonal next to two other showing rearrangement. As coexpression TdT under physiologic circumstances restricted pro/pre- pre-B cells we propose, on basis our results, that origin rather than postmitotic cells. MCPyV infection transformation pro-/pre-B are likely induce simple cytokeratins as shown SV40 nonepithelial This model cellular ancestry might impact therapy possibly helps understand why approximately 20% MCPyV-negative.