Punctal Stenosis: Histopathology, Immunology, and Electron Microscopic Features-A Step Toward Unraveling the Mysterious Etiopathogenesis

Purpose: To study the histologic, immunohistochemical, and electron microscopic features of puncta and proximal vertical canaliculi to understand the etiopathogenesis of punctal stenosis. Methods: Prospective study of 26 stenosed punctae that were collected following a punctoplasty. Sixteen were from lower eyelid and 10 from upper eyelid. Histopathological examination was performed on 20 punctae using hematoxylineosin, periodic acid-Schiff, and Masson trichrome staining. Immunohistochemical patterns were analyzed after staining with leukocyte common antigen or CD45, CD3, CD5, CD10, CD20, CD138, and smooth muscle actin. Six punctae (3 upper, 3 lower) were separately processed for electron microscopic studies as per standard protocols. Results: All punctae showed evidence of subepithelial and subconjunctival fibrosis. Thirty percent (6/20) showed extensive fibrosis. Inflammation was noted in 80% (16/20) of the samples; however, 20% (4/20) showed severe inflammation. Strong immunoreactivity was noted, with CD45 and CD3 in 80% (16/20) with predominance in the subepithelial areas. Focal immunoreactivity was noted for CD10, CD20, and CD138. Immunoreactivity was negative for CD5. Electron microscopic features include blunted epithelial microvilli, numerous fibroblasts, extensive and irregularly arranged collagen bundles, mononuclear infiltration in the vicinity of fibroblasts or in between collagen bundles, and inter-and intracellular edema in areas of inflammation. Conclusions: Chronic inflammation and subsequent fibrosis appear to be the basic ultrastructural response to various noxious stimuli. Mononuclear inflammatory infiltration in the vicinity of fibroblasts could possibly reflect a close cellular interaction between these 2 cells.