CD34

CD34 is a 110 kDa transmembrane glycosylated protein expressed on vascular endothelial cells and hematopoietic progenitor cells, making it a sensitive but not specific marker for neoangiogenesis. In IHC, it shows membranous staining and is widely used to distinguish soft tissue tumours, such as CD34‑positive dermatofibrosarcoma protuberans, solitary fibrous tumour, hemangiopericytoma, and Kaposi sarcoma, from CD34‑negative tissues like dermatofibroma. CD34 also aids in differentiating liver lesions being positive in the sinusoidal spaces of hepatocellular carcinoma but negative in focal nodular hyperplasia and serves as a marker of hematopoietic blasts in leukemias. Endothelial cells act as a built‑in positive control for staining (1).

Recommended Controls

Criteria for acceptable staining is a membranous staining pattern. Recommended controls to include sections of appendix and liver. Appendix: The endothelial cells of all vessels should show a distinct predominantly membranous staining reaction. Liver: the endothelial cells of the portal vessels and the periportal sinusoids should show a distinct moderate to strong staining reaction. Hepatocytes should be negative.

Expected staining pattern

Normal breast

Appendix mucosa

Normal liver

Disclaimer

These methods are intended as a guide only. Laboratories that wish to implement these methods should perform internal validation/verification prior to use. The RCPAQAP does not make any claim or warranty for the accuracy or performance of these methods.