Histopathologic Clues in Diagnosing Oral Mucosal Grafts to the Conjunctiva.

Excised redundant, forniceal "conjunctival" tissue from a 67-year-old man who experienced a chemical injury to his OS 25 years earlier was evaluated histopathologically with the hematoxylin-eosin, periodic acid Schiff (PAS) with and without diastase, mucicarmine, and Alcian blue methods. Additional immunoperoxidase testing for gross cystic disease fluid protein-15 (GCDFP-15) was undertaken. Non-keratinizing squamous epithelium composed of 8 to 10 layers of swollen keratinocytes without goblet cells surmounted a variably dense and well-vascularized collagenized lamina propria deep to which, in submucosal fibroadipose tissue, was embedded an accessory gland. The acini of the gland were composed of both GCDFP-15-positive serous cells and mucicarmine-positive goblet cells, indicating they were seromucinous rather than entirely serous, as is characteristic of normal lacrimal glandular tissue. Different features of the surface epithelium, the lamina propria, and the submucosa can separate the conjunctival and oral mucous membranes. A close analysis of the cytologic composition of associated accessory glands can reinforce the correct diagnosis of an oral mucous membrane graft when the past surgical history is unclear, because only serous cells but not mucocytes comprise the lacrimal glandular units.