Malignant transformation of a conjunctival keratoacanthoma requiring enucleation.

We report a rare case of rapid transformation of a conjunctival keratoacanthoma (KA) into a highly aggressive squamous cell carcinoma requiring enucleation. To our knowledge, this is the second such case reported in the literature. Case report. A 73-year-old man presented with a recurrent conjunctival lesion in the right eye. A slit lamp examination revealed a hyperkeratotic lesion in the limbar conjunctiva adhered to deep planes but with no ocular involvement. An incisional biopsy was performed because an area of scleromalacia was observed underlying the lesion. Histological findings were consistent with conjunctival KA. One week later, a raised lesion was observed invading the anterior chamber. Histological examination of another excisional biopsy specimen indicated conjunctival squamous cell carcinoma. The right eye was enucleated. Histological analysis confirmed intraocular tumor invasion. Complete clinical remission was observed over one year of follow up. Although conjunctival keratoacanthoma is normally benign, it is important to correctly differentiate between KA and squamous cell carcinoma, and closely monitor the eye after surgery because of the rare possibility of recurrence or conversion to squamous cell carcinoma. Immunohistochemistry could help in the diagnosis and management of dubious cases.