Langerhans cell histiocytosis of the caruncle.

A 37-year-old man presented with the complaint of a small non-tender mass growing steadily on the left caruncle for 3 months. This was a soft, reddish-yellow tumour, occupying the whole left caruncular area without impinging on the conjunctiva. Histopathological evaluation of the excisional biopsy specimen showed that the tumour was largely composed of Langerhans cells mixed with eosinophils and mature lymphocytes. There were strong CD1a and S-100 positivity on immunohistochemical studies. Langerhans cell histiocytosis is an exceedingly rare tumour of the caruncle in the adult and this lesion cannot be distinguished from other amelanotic lesions on clinical grounds alone. Simple excision of the lesion provided a 4-year disease-free period.