Pigmented plaque presentation of dematiaceous fungal keratitis: a clinicopathologic correlation

Abstract

Purpose: To evaluate the clinical, microbiologic, and histopathologic features of dematiaceous fungal keratitis cases presenting with pigmented, raised, plaque-like infiltrate. Study Design: Consecutive case series. Methods: Microbiology-proven cases of fungal keratitis presenting with a pigmented infiltrate were included in the study. A detailed clinical and microbiological evaluation was performed in all cases. The lesion was removed by superficial keratectomy, and the specimen was subjected to histopathologic examination. Patients presenting with a large infiltrate had penetrating keratoplasty, and the corneal button was submitted for histopathology examination. Results: We enrolled 15 cases in the study. There were 11 men and 4 women. The mean age of the patients was 48.5 years (range 27-68 years). The patients presented to us with duration of symptoms ranging from 7 to 60 days (mean 27.6 ± 15.6, median 30). The visual acuity was better than 20/200 in 9 (60%) cases. The infiltrate size varied from 4.3 to 64 mm² (mean 26.9 ± 16.6, median 22.5). Ten (66.7%) cases had a central infiltrate. The infiltrate was dry and raised, with brown to black pigmentation on its surface. Corneal scrapings revealed septate fungal filaments in all cases and the characteristic brown to black pigmentation of the fungal cell wall in 10 (66.7%) cases. Although there was a significant growth of dematiaceous fungi on culture in all cases, species identification could be done in 3 cases only. Examination of tissue sections revealed a carpet of pigmented fungal filaments on the corneal surface (n = 12, 92.3%) associated with mild to moderate inflammation (n = 11, 84.7%) and tissue destruction. Nine out of 11 cases that had keratectomy resolved with medical therapy. Conclusions: The pigmented plaque-like infiltrate in dematiaceous fungal keratitis consists of surface colonization of pigmented fungal filaments associated with mild to moderate inflammation and tissue destruction of the underlying corneal stroma.