CD34 - A REVIEW

The CD34 antigen was originally described as a marker for human hematopoietic stem cells. It has subsequently been identified on a small number of other normal cell types and has been found to be prominently expressed in a diverse group of neoplasms including leukemias, vascular neoplasms, hemangiopericytomas, nerve sheath tumors, epithelioid sarcomas, dermatofibrosarcoma protuberans, solitary fibrous tumors, smooth muscle neoplasms, and gastrointestinal stromal tumors. For many of these neoplasms the reaction with CD34 antibodies can be diagnostically helpful as CD34 antigens tend to be absent from many common lesions in their differential diagnoses such as carcinoma, melanoma, lymphoma and most types of sarcoma. The function of the CD34 molecule remains unknown and the explanation for its expression by such diverse neoplasms is unclear. A number of antibodies that belong to the cluster differentiation group CD34 have been described. This review focuses on MY 10 and QBEND10, two antibodies that have been shown to react with antigens in paraffin-embedded tissue.