Poorly differentiated neuroendocrine carcinoma of the eyelid

Purpose: To report a case of poorly differentiated neuroendocrine carcinoma of the eyelid. Case summary: A 70-year-old male presented with a 5-month history of a right upper eyelid mass. The mass appeared as 1.2 × 1.2 cm on the right upper eyelid. A mass excision was performed under frozen section control. The tumor was completely excised with a safety margin clearance and an upper eyelid reconstruction was performed. Histopathological examination revealed a tumor composed of small atypical cells which showed a high nuclear/cytoplasm ratio, nuclear molding, and increased mitotic activity. Immunohistochemical examination revealed positive reactivity for Ki-67, synaptophysin, CD56, and negative reactivity for chromogranin, cytokeratin 20, and thyroid transcription factor-1. Conclusions: Primary neuroendocrine carcinoma of the eyelid is extremely rare, but the tumor has high malignancy and readily metastasizes. Poorly differentiated neuroendocrine carcinoma should be considered in the differential diagnosis of a rapidly growing eyelid mass.