Answer: Blue nevus

Histology: The nasal submucosa demonstrates an area of dense pigment deposition that, on special stains, is found to represent melanin. Do to the obscuring effects of the heavy pigment deposition, the morphologic features of the pigmented cells are not easily appreciated although many of the cells demonstrate a fusiform or dendritic appearance. Junctional activity in the overlying respiratory epithelium is not noted.

Discussion: As is well demonstrated in the present case, blue nevus is characterized by heavy melanin deposition, a proliferation of dendritic melanocytes, and the absence of junctional activity. Blue nevus of the ordinary type typically arises from the skin of the head and neck area. Reports sites of extra-cutaneous origin include lymph nodes, prostate, breast, vagina, oral cavity and others. This case emphasizes the point that a pigmented lesion of the intranasal mucosa should not be assumed to represent a mucosal melanoma just because it is producing melanin. On rare occasions, benign melanocytic lesions can occur in the sinonasal cavity.