A rare conjunctival Spitz nevus: a case report and literature review.

A conjunctival Spitz nevus is a very rare, benign melanocytic lesion, which can be mistaken for a malignant melanoma. We present a case of a 28-year old man, who suffered from a rapidly growing, non-pigmented mass in the left caruncular area, extending to the nasal conjunctiva. The lesion was excised and pathologic examination showed nests of large, polygonal, non-pigmented epithelioid cells, located in the stroma. The overlying epithelium showed focal erosions. At the base, there was a lymphocytic infiltrate. Immunohistochemical techniques, with stainings for S-100 protein, HMB-45 and MIB-1, were used for further investigation and showed the melanocytic origin of the lesion (S-100 staining) as well as many cells in cell cycle (MIB-1 staining). However, no mitoses were seen. The clinical image, combined with pathologic and immunohistochemical findings, provided the diagnosis of a Spitz nevus localised in the conjunctiva. Although the cutaneous location of Spitz nevi is well known, conjunctival Spitz nevi are very rare and because of their mucosal origin, some of the histological features are different.