Solitary circumscribed neuroma of the conjunctiva: Differential diagnosis from neurofibroma is a must? / Neuroma circunscrito solitário da conjuntiva: diagnóstico diferencial de neurofibroma obrigatório?

ABSTRACT 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.

RESUMO Um homem de 42 anos apresentou uma massa na conjuntiva palpebral inferior direita, próxima ao punctum, com evolução de 4 semanas. Uma biópsia excisional da lesão e o subsequente exame anatomopatológico revelaram que a massa era composta de células de Schwann com núcleos cônicos, croma­tina fina e nucléolos não visíveis. Ao exame imuno-histoquímico, as células fusiformes mostraram-se difusa e fortemente positivas para a proteína S100. A imunocoloração também foi positiva para neurofilamentos e evidenciou os axônios. Considerando esses achados, o tumor foi diagnosticado como um neuroma circunscrito solitário. Procedeu-se uma investigação completa para neoplasia endócrina múltipla tipo 2b, entretanto, estigmas característicos e história familiar não foram detectados. Assim, o diagnóstico foi firmado como neuroma circunscrito solitário, condição rara cujo diagnóstico diferencial baseia-se no exame anatomopatológico e na avaliação imuno-histoquímica. Já que esse tumor pode estar relacionado à neoplasia endócrina múltipla tipo 2b, torna-se essencial, nesses casos, a investigação da neoplasia de forma sistemática.

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.