Describe rhinosporidiosis.

Rhinosporidiosis

• Rhinosporidiosis is a chronic granulomatous infection caused by rhinosporidium seeberi, which produces friable, vascular, polypoidal masses in the nose and nasopharynx.
• It is endemic in INDIA and SRI LANKA, which together account for the great majority of cases in the world.
• The organism was long classified as a fungus but is now placed among the mesomycetozoea, a group of aquatic protistan parasites — and, importantly, it cannot be cultured in vitro.
• Transmission is thought to be from stagnant water — the classical history is of bathing in ponds, tanks or rivers, or of occupational exposure such as sand-digging in river beds. It is commoner in males and in rural populations
• Presentation — unilateral nasal obstruction and recurrent epistaxis.
• The appearance IS distinctive and is what makes the clinical diagnosis: a pink to purplish-red, soft, lobulated, polypoidal mass, frequently pedunculated.
• Sites — most often the nasal septum, the floor and the inferior turbinate; also the nasopharynx, conjunctiva and lacrimal sac, larynx, skin and genitalia; and it may prolapse into the pharynx
• Histology is diagnostic — numerous thick-walled sporangia (up to 300 micrometres) containing thousands of endospores, at various stages of maturation, within a vascular stroma with a chronic inflammatory infiltrate; stained by PAS and methenamine silver
• Treatment is complete surgical excision with cautery (or diathermy) of the base.
• Recurrence is common and is due to spillage of endospores onto adjacent mucosa — hence wide excision, cauterisation of the base, and avoidance of piecemeal removal
• Operate with adequate preparation for bleeding.
• Dapsone is used as an adjuvant, believed to arrest sporangial maturation and promote fibrosis, and is given for months to reduce recurrence; antifungals are ineffective, which follows from the organism not being a true fungus
• Advise against bathing in stagnant ponds and tanks, which is the only available preventive measure and is worth stating in an Indian context
• The differential — a bleeding polypus of the septum (haemangioma), an antrochoanal polyp, angiofibroma in an adolescent male, inverted papilloma, and malignancy — which is why every such mass is sent for histology however typical it looks
• White dots on a red polyp are sporangia seen through the epithelium.
• It cannot be cultured, so the diagnosis is histological and no swab or culture will help
• Ask about bathing in ponds and tanks; the exposure history is characteristic and is not volunteered
• Bleeding is out of proportion to the size, because the mass is highly vascular, so prepare for haemorrhage