Solitary keratoacanthoma of the conjunctiva.

Two ranch workers had rapidly-growing crateriform conjunctival nodules excised without recurrence. Histopathologically, these lesions consisted of acanthotic epithelium characterized by prominent keratin formation both within cells and in horn pearls. Although both clinically and histologically they resemble squamous cell carcinoma, keratoacanthomas are benign tumors commonly thought to arise in hair follicles. The presence of these lesions on conjunctiva and other epithelia without hair in the two cases described was evidence against this hypothesis.