Anatomic pathology selected abstracts
December 2020—It can be difficult to distinguish metastatic melanoma from melanocytic nevi in lymph nodes. Because diffuse IHC PRAME (preferentially expressed antigen in melanoma) expression is detected in the majority of primary and metastatic melanomas, but rarely in nevi, the authors conducted a study in which they hypothesized that PRAME could be a useful adjunct marker for the diagnosis of melanocytes in lymph nodes. They examined 45 nodal melanocytic deposits comprising 30 nodal nevi and 15 melanoma metastases. The latter were not straightforward from a diagnostic perspective because they coexisted with nodal nevi or were present in perinodal fibrous tissue. All nodal nevi were negative for PRAME and all melanoma metastases were diffusely positive for PRAME IHC.