- Protozoan head and neck infection previously mistaken for a fungal infection
Background
Microbiology
- 18S rDNA sequencing has shown that Rhinosporidium seeberi is a protistan parasite
- Has never been cultured
- Forms round, thick-walled cysts (sporangia) in the submucosa, varying in diameter from 100 to 350 μm, often visible through the mucosa as white dots
- Mature cysts become filled with numerous spores (endospores), which on release become new cysts — kind of like Coccidioides
Epidemiology
- Occurs worldwide, with most cases in India and Sri Lanka
Clinical Manifestations
- Rhinosporidiosis is a chronic, usually painless localized pedunculated masses of the mucous membranes
- Lesions increase over months to years
- Most commonly affects the nose and nasopharynx, sometimes presenting with nasal obstruction or epistaxis
- Can also affect the eye or orbit, and rarely the skin as verrucous pedunculated lesions
- Rare cases involve the vagina, urethra, or penis
- Dissemination is rare
Diagnosis
- Presumably clinical suspicion with or without PCR or DNA sequencing
- With appropriate history, may be able to determine from biopsy
- Differential for spherules: Coccidioides, Rhinosporidium, Emmonsia
Management
- Surgery with electrocoagulation of the lesion base
Further Reading
- Pfaller MA and Diekema DJ. Unusual Fungal and Pseudofungal Infections of Humans. J Clin Microbiol. 2005;43:1495. doi: JCM.43.4.1495-1504.2005
