Interplay of Immune Cells in Mooren Ulcer.

PURPOSE: To report the histopathological findings of the cornea with fulminant Mooren ulcer, an idiopathic autoimmune keratitis.

METHODS: A 54-year-old woman was diagnosed with Mooren ulcer. Despite intensive immunosuppression, corneal perforation developed, and penetrating keratoplasty with a limbal tectonic graft was performed. The removed cornea was histopathologically evaluated for the phenotype of the cells infiltrating the lesion.

RESULTS: Hematoxylin-eosin staining showed massive infiltration of inflammatory cells in the anterior corneal stroma and epithelial hyperplasia in the adjacent conjunctiva. Further analysis with immunohistochemistry indicated that the cells infiltrating the lesion included a number of CD4⁺ and CD8⁺ T lymphocytes, CD19⁺CD45⁺ B lymphocytes, and CD14⁺CD68⁺ macrophages. There were a few neutrophils and no CD56⁺ NK cells.

CONCLUSIONS: Our findings suggest that multiple types of immune cells including T cells, B cells, and macrophages are involved in the pathogenesis of Mooren ulcer.