Over the last two decades the application of immunologic research methods to histopathology has resulted in marked improvement in the diagnosis of neoplasms. Immunohistochemistry plays important role in the early detection of potentially malignant neoplasms. Immunohistochemistry has also provided insight into tumor histopatho- genesis and has contributed to more accurate determination of patient prognosis apart from diagnosis. Predictable tumor expression of many antigens as their cells of origin or normal tissue counterparts validates the principle of tumor classification by immunohistochemistry.