Histopathologic and Immunohistochemical Evaluation of the Lens Capsule in a 4-Year-Old With Unilateral Posterior Subcapsular Cataract: A Case Report

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Purpose: To immunohistochemically investigate the pathogenesis of unilateral posterior subcapsular cataract in a 4-year-old girl.

Case report: The patient was diagnosed with unilateral posterior subcapsular cataract in the left eye after an abnormality was noted at 3 years of age. Examination showed a localized opacity confined to the posterior subcapsular region, causing form-deprivation amblyopia. At 4 years of age, she underwent cataract surgery with posterior capsulotomy and anterior vitrectomy. Excised anterior and posterior capsule specimens were examined histopathologically and immunohistochemically for aquaporin-1 (AQP1), α-smooth muscle actin (α-SMA), and advanced glycation end products (AGEs). The anterior capsule showed no morphologic abnormalities. In contrast, the posterior capsule showed thickening (42.2 µm) along with flattened atypical cells. Both anterior and posterior capsule specimens were positive for AQP1 and negative for α-SMA and AGE.

Conclusions: AQP1 positivity in the posterior capsule suggests that atypical cells were derived from lens epithelial cell (LEC) components. Negative α-SMA staining did not support epithelial–mesenchymal transition, and negative AGE staining suggested a mechanism distinct from glycation-related changes in age-related cataract. These findings suggest that abnormal capsular secretion due to aberrantly migrating or developmentally retained LEC components contributes to posterior capsular thickening and opacity.