Although researchers reported that PAX5 expression was detected in non-hematopoietic tumors such as neuroendocrine tumors, Merkel cell carcinoma, and mesonephric tumors [3, 4], Kolhe et al [5] demonstrated that pulmonary small cell carcinoma was negative PAX5 expression of the immunohistochemical staining. The gene discussed is PAX5; the disease is mesonephric neoplasm.