Desmoplastic neurotropic melanoma: A diagnostic trap

Abstract

Desmoplastic neurotropic melanoma (DNM) is known as a rare variant of cutaneous melanoma. The authors defined the term `neurotropic' which is used to refer to the associated nerve infiltration or neural differentiation. A 74-year-old female applied to the plastic surgery clinic with a one-year history of a nodule in the left infraorbital skin. The lesion was excised by the surgeons and was sent to the pathology department. The tumor with spindle cells in a scar-like stroma was detected microscopically and diagnosed as a `dermatofibroma'. Eight months after surgery, a deep-seated nodule recurred at the same place. This nodule was re-excised. In this sample, we observed hypercellularity, atypical mitoses and nerve infiltration of the spindle tumor cells having strong positive staining with S-100 protein and negative staining with HMB-45, thus, the ultimate diagnosis was DNM. The differential diagnosis of this lesion includes many benign and malignant entities. This is crucial because of the potential for recurrence and metastasis of the lesion.