What are the common immunohistochemical (IHC) markers utilized in the diagnosis of melanoma? Most melanomas can be diagnosed on routine histology, but IHC staining can be useful in the difficult cases. A wide range of melanoma- and melanocyte-associated antigens have been identified for use in IHC staining. The most commonly utilized ones are as follows: - S100: A calcium-binding protein that is expressed in melanocytes, Schwann cells, glial cells, chondrocytes, adipocytes, myoepithelial cells, macrophage, Langerhans cells, and dendritic cells. Despite its low specificity, S100 has a high sensitivity for melanocytes and melanoma.
- gp100: A glycoprotein considered to part of the premelanosome complex. HMB45 is the most commonly utilized antibody to detect gp100. HMB45 has a higher specificity for melanocytes and nevus cells, but its use is limited by its sensitivity, with false negative rates up to 35%.
- MART1: A melanocyte differentiation antigen known as melanoma antigen recognized by T cells–1. It represents a protein associated with melanosomes. MART1 is more specific than S100 and HMB45, as well as more sensitive than HMB45.
Other less commonly used markers include microphthalmia-associated transcription factor (MITF) and tyrosinase, but their utility is limited to determining the melanocytic origin of a lesion. Piris A, Mihm MC Jr: Progress in melanoma histopathology and diagnosis, Hematol Oncol Clin North Am 23:467–480, 2009. |
