Rosette‐like formations in melanocytic neoplasms: A case report and literature review

AbstractHomer‐Wright‐like rosettes are a common finding in neural tumors but seldom seen in melanocytic nevi and melanoma. We report a case of a 23‐year‐old male with a compound melanocytic nevus with such rosette‐like structures and summarize the current literature on this histopathological feature in melanocytic neoplasms. A symmetric, well‐circumscribed, compound nevus consisting of aggregations of epithelioid melanocytes with eccentric nuclei and central eosinophilic cytoplasm, resembling Homer‐Wright rosettes, was present on biopsy. Immunohistochemical stains strongly supported a melanocytic entity and were negative for NTRK1/2/3, a fusion protein potentially associated with rosette‐like structures. We found 17 other cases of benign melanocytic nevi, including 9 atypical Spitz tumors and 6 Spitz nevi, and 11 malignant melanomas, including 3 Spitz melanomas and 4 metastases. We observed remarkable diversity among lesion morphologies containing rosettes, as well as level of prominence and cytology of the rosettes themselves. This case illustrates the morphologic malleability of neural‐crest‐derived lesions to share microscopic and phenotypic attributes.