Histopathological examination of Acanthamoeba sclerokeratitis

Kumiko Kato,1 Koji Hirano,2 Tetsuro Nagasaka,3 Koichi Matsunaga,1 Yuko Takashima,1 Mineo Kondo1 1Department of Ophthalmology, Mie University School of Medicine, Tsu, Japan; 2Department of Ophthalmology, Fujita Health University, Nagoya, Japan; 3Department of Medical Laboratory Science, Nagoya University Graduate School of Medicine, Nagoya, Japan Purpose: To report the histopathological findings in a case of severe Acanthamoeba sclerokeratitis (ASK). Patient and methods: A 46-year-old patient was referred to the Department of Ophthalmology of Mie University Hospital because of a severe corneal ulcer of the right eye of 6 months' duration. Our initial examination showed a ring-shaped corneal opacity with extensive epithelial defects and nodular scleritis. Cysts of Acanthamoeba were identified in cultures from corneal scrapings, and he was diagnosed with ASK. He was started on antiamoebic treatment, including topical micafungin and chlorhexidine. The corneal ulcer was debrided several times. One month later, he developed necrotizing scleritis, and the cornea suddenly perforated. The eye was enucleated because of severe pain and prepared for histopathological examination. Results: The histopathological examination showed an infiltration of polymorphonuclear leukocytes throughout the corneal stroma and also in the limbal area of the sclera, forming an abscess. Granulation tissue was observed in the anterior sclera close to the ciliary body, but the posterior regions of the eye were not affected by inflammation or tissue destruction. The cysts of Acanthamoeba were observed only in the cornea. Conclusion: Histopathological examination of an eye with severe ASK showed that the inflammation and tissue granulation were present only in the anterior part of eye, and the posterior segment was not affected. Because the inflammation and tissue destruction were confined to the anterior segment, enucleation might not have been necessary if the severe pain was able to be controlled. Keywords: Acanthamoeba sclerokeratitis, histopathology, acute and chronic inflammation, enucleation