Revisiting PAX-8's Labeling of Merkel Cell Carcinoma

摘要

To the Editor:We read your report of PAX-8's sensitivity for Merkel cell carcinoma (MCC) with great interest and used our assay on a number of clinical cases. However, over time our observations deviated from the reported findings. We performed a study of our PAX-8 immunohistochemical protocol to more systematically investigate this. We tested Cell Marque's prediluted PAX-8 monoclonal antibody (MRQ-50 clone) on 20 MCCs, 14 primaries, and 6 metastatic MCCs. The protocol was performed on formalin-fixed, paraffin-embedded tissues, with antigen retrieval in Cell Conditioning 1 solution (Ventana, Tucson, Arizona) for 60 minutes, primary antibody incubation for 32 minutes at 37癈, and detection with the ultra View DAB Detection Kit. Only nuclear labeling was assessed for intensity (0-3+) and extent (0 = 50%). The more sensitive, polyclonal Cell Marque PAX-8 antibody examined in the original article was not studied.