Cellular neurothekeoma of the eyelid: a unique internal palpebral presentation.

: A 50-year-old woman presented with a mass lesion of the inferolateral palpebral conjunctiva similar in appearance to a chalazion, but unusual enough in presentation that excisional biopsy was initially performed. Histopathologic analysis revealed a dermal fibrohistiocytic neoplasm consistent with cellular neurothekeoma. Neurothekeoma is a benign tumor; the cellular variant is rare and of unclear histogenesis. Completely internal eyelid location is particularly rare, with other identifiable case reports of cellular neurothekeoma palpebrae referring to external or unspecified eyelid location. This case provides an example of the chalazion as masquerader and re-emphasizes the importance of maintaining a broad differential diagnosis and high index of suspicion regarding atypically appearing chalazia.