Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody . CD15 (X hapten) is a cell surface glycoprotein involved in the regulation of neutrophil functions. CD15 is frequently used as a marker for normal and neoplastic myeloid cells and monocytes. In combination with CD30, CD15 is commonly used as a marker for Reed Sternberg cells in classical Hodgkin’s lymphoma. CD15 is also expressed on different carcinoma types but negative in mesothelioma. Carcinomas positive for CD15 are reported to have worse prognosis.