FONSECAEA PEDROSOI: A TENACIOUS TENANT OF THE IMMUNOSUPPRESSED

To report a rare case of fungal keratitis by Fonsecaea pedrosoi in an immunocompromised host

Dr. Rajendra Prasad Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi

An elderly male, post concurrent chemoradiotherapy for squamous cell carcinoma of the pyriform fossa, presented with redness, watering and diminution of vision in the right eye for two weeks. His visual acuity was perception of light with inaccurate projection of rays, globe was hypotonus. Slit lamp examination revealed 8mm x 8mm corneal epithelial defect with dense infiltrates and brown pigmentation along with perforation and pseudocornea formation, with flat anterior chamber. Ultrasonography revealed choroidal detachment. Microbiological workup revealed sparingly branched, brownish conidiophores with clusters of club-shaped, one-celled conidia in short, unbranched chains (Cladosporium-like conidiation) suggestive of Fonsecaea pedrosoi.

The patient underwent Right Eye Therapeutic Keratoplasty. Post-operatively, Visual acuity was Hand Motions close to face, with Accurate projection of rays, and normal intraocular pressure. He was simultaneously started on topical Amphotericin-B and systemic Itraconazole and was advised to continue systemic Antifungal therapy for a long duration but four weeks later, passed away due to complications of systemic chemotherapy.

Chromoblastomycosis is caused by dematiaceous fungi which synthesise and deposit melanin in their cell walls, occurring mainly in humid tropical and subtropical regions. F. pedrosoi is the most common cause of cutaneous chromoblastomycosis but infrequently causes keratitis, mainly after trauma with vegetative matter. TLR-2 and TLR-4 are essential receptors for recognizing F. pedrosoi and activating the immune system. Neutrophils are important for killing F. pedrosoi conidia and hyphae. Immunosuppression could have played a major role in this case.