Small cell neuroendocrine carcinoma with primary orbital involvement - The unseen, and a review of literature.

Neuroendocrine neoplasms are derived from the epithelial lineages mainly of respiratory tract, with predominant neuroendocrine differentiation. There are only a handful of documented cases of paranasal small cell neuroendocrine carcinomas (SNEC) with primary orbital involvement. Here, the authors describe a 33-year-old male patient with rapidly progressive swelling of the right lower lid with proptosis since 4 weeks. On contrast-MRI orbit, an ill-defined multilobulated mass measuring 3.6 × 3.1 cm with intense homogenous enhancement was seen in the right retrobulbar space involving the right ethmoid sinus. On incisional biopsy, a poorly differentiated mass containing numerous small round blue cells and scanty intervening stroma with prominent necrosis and apoptosis was seen. Immunohistochemistry was strongly positive for synaptophysin. He was diagnosed as a case of SNEC and received chemotherapy, with good response till date of 9 months of follow up. The authors present a literature review and describe challenges in management of a primary orbital SNEC.