Question
Rhinosporidiosis
Answer
Rhinosporidiosis is a chronic granulomatous infection, most classically affecting the nasal mucosa, caused by Rhinosporidium seeberi — an organism of uncertain and historically debated taxonomic classification, now generally regarded as an aquatic protistan parasite (belonging to a novel clade, Mesomycetozoea) rather than a true fungus, though it has traditionally been studied and taught alongside fungal infections given clinical/histopathological similarities.
Epidemiology/transmission: associated with exposure to stagnant water (bathing in ponds/rivers) or contact with soil/dust in endemic areas (notably South Asia, including India, where it is relatively common); presumed transmission via direct inoculation of spores into traumatized nasal/ocular mucosa from contaminated water.
Clinical features: presents classically as a slow-growing, friable, vascular, polypoid (papillomatous) mass in the nasal cavity, causing nasal obstruction and recurrent epistaxis (bleeding, due to the lesion’s high vascularity) — the nose is the most common site, though conjunctival, ocular, and, less commonly, other mucosal or cutaneous sites can be involved.
Laboratory diagnosis: primarily histopathological — biopsy of the lesion shows large, thick-walled sporangia (up to 200–300 μm) containing numerous small endospores, giving a characteristic appearance on light microscopy; direct crush smear/KOH preparation of the friable tissue can also demonstrate the characteristic sporangia; the organism has never been successfully cultured in vitro on artificial media, a distinctive feature complicating laboratory confirmation and contributing to the historical uncertainty about its precise taxonomic classification.
Treatment: surgical excision with wide margins (including cauterization of the base) is the mainstay of treatment, since no reliably effective antimicrobial/antifungal therapy exists; recurrence after incomplete excision is common, given the friable, vascular nature of the lesion making complete removal technically challenging.