Rhinosporidium seeberi

From IDWiki
Rhinosporidium seeberi
  • 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