Conjunctival epithelial hyperplasia in a patient with a nodular lesion in the palpebral conjunctiva: A case report.

The conjunctiva is a thin and delicate mucous membrane lining the inner eyelid and the anterior surface of the eyeball. Although hyperplastic changes can occur due to nonspecific chronic inflammation, 'conjunctival epithelial hyperplasia' has not been sufficiently established as a pathological entity. Additionally, the immunohistochemical (IHC) features of both the intact conjunctiva epithelium and conjunctival epithelial hyperplasia have not been sufficiently evaluated. The present report describes the case of an 86-year-old man who consulted with an ophthalmologist for a 6-month-old nodular lesion on his left eye. Located in the medial aspect of the left lower palpebral conjunctiva, the lesion was slightly erythematous and smooth. An excisional biopsy of the lesion was performed to obtain a pathological diagnosis. The hematoxylin and eosin sections revealed a thickened conjunctival epithelium composed of hyperplastic cuboidal epithelial cells and goblet cells, indicating conjunctival epithelial hyperplasia. Atypia, increased mitosis and a papillomatous architecture, indicative of neoplastic changes, were not observed. This resulted in conjunctival squamous intraepithelial neoplasia and squamous cell papilloma being ruled out. IHC analysis was performed to further characterize the lesion as well as the intact conjunctival epithelium. The thick conjunctival epithelium was composed of epithelial cells that stained positive for cytokeratin [AE1/AE3 (intensity: +), CK5/6 (intensity: ++), and CK7 (intensity: +)] and p63-positive basal cells (intensity: +) whose presence in the conjunctiva has received insufficient recognition. Moreover, squamous metaplasia was found in a segment of the thick conjunctiva, which exhibited IHC features similar to those of hyperplasia. CK5/6 was positive, indicating endogenous squamous differentiation of the conjunctival epithelial hyperplasia. These findings led to the diagnosis of conjunctival epithelial hyperplasia as a pathological entity. Further collection and analysis of several cases of conjunctival epithelial hyperplasia may lead the development of preventative methods and drug treatments for this lesion, and additional prognostic data, such as the recurrence rate.