Dr. Meehan on Importance of IHC Testing in Melanoma

Shane A. Meehan, MD, associate professor, Ronald O. Perelman Department of Dermatology, associate professor, Department of Pathology, director of the Dermatopathology Fellowship Training Program, and director of the Dermatopathology Section at New York University Langone Medical Center, discusses the importance of immunohistochemistry (IHC) testing in melanoma.

It is important for oncologists to know about the significant role IHC has in the analysis of melanocytic lesions, Meehan explains. Its most important function is to determine melanocytic differentiation when one sees a poorly differentiated tumor. There are a variety of antibodies to use in order to determine that melanocytic differentiation, he adds, including S100, SOX10, MelanA, and HMB45. Depending on the particular profile of these markers and what particular antigens they can stain, some may be more useful for the diagnosis of desmoplastic melanoma than the diagnosis of melanoma in situ.

Dermatopathologists weigh the pros and cons of each of these antibodies in how to work up a melanocytic lesion depending on the suspicion of its particular type. There are other markers that we can use besides the melanocytic ones, a lymphatic one called D240, and also a proliferation marker called Ki-67.