Solitary Circumscribed Neuroma Of The Conjunctiva: Differential Diagnosis From Neurofibroma Is A Must?

A 42-year-old male presented with a 4-week history of a mass in the right inferior palpebral conjunctiva close to the punctum. An excisional biopsy of the lesion and histopathological examination revealed that the mass was composed of Schwann cells with thin conical nuclei, fine chromatin, and unnoticeable nucleoli. Immunohistochemically, the spindle cells were diffusely and strongly positive for S100 protein. Neurofilament immunostaining was also positive, which highlighted axons. In light of these findings, the tumor was diagnosed as solitary circumscribed neuroma. A comprehensive evaluation for multiple endocrine neoplasia type 2b was performed. However, no multiple endocrine neoplasia type 2b stigmata and no family history were detected. The diagnosis was therefore finalized as solitary circumscribed neuroma, which is considered as a rare condition. The differential diagnosis is based on the histopathological examination and immunohistochemical evaluation. As the tumor can be related with multiple endocrine neoplasia type 2b, it is essential to systematically investigate for multiple endocrine neoplasia type 2b in such cases.