Table of Contents
Definition / general | Risk factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Differential diagnosisCite this page: Pernick N. Rhinosporidiosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/nasalrhinosporidiosis.html. Accessed March 28th, 2024.
Definition / general
- Caused by Rhinosporidium seeberi, traditionally thought to be a fungus but actually an aquatic protistan parasite (J Clin Microbiol 1999;37:2750)
- Endemic in southern India, Sri Lanka and emigrants from this region (Diagn Pathol 2006;1:25, Singapore Med J 2004;45:224); rare indigenous cases in U.S. (South Med J 1996;89:65)
- Natural aquatic habitat, transmitted through traumatized epithelium, most commonly in nose and eye, also skin, ear, genitals and rectum
Risk factors
- Bathing or working in stagnant water
- Rarely presents with disseminated skin disease (Indian J Dermatol Venereol Leprol 2007;73:185, Indian J Dermatol Venereol Leprol 2001;67:332)
- Not transmitted person to person
Case reports
- 29 year old man from India with progressively increasing nasal obstruction (Case of the Week #97)
Treatment
- Surgical excision, may recur
- No effective medical treatment
Gross description
- Hyperplastic, polypoid, red, granular masses of nasal cavity
- Yellow pinhead spots represent mature sporangia
- Superficial mucus is common
Microscopic (histologic) description
- Large (100 - 450 microns), thick walled sporangia with 1000+ endospores, each 6 - 10 microns, accompanied by a mixed inflammatory infiltrate
- May not be present in all sections and may need additional sampling for diagnosis
Microscopic (histologic) images
Contributed by Hanni Gulwani, M.B.B.S. (Case #97), Veena Maheshwari, M.D., Kiran Alam, M.D., Anshu Jain, M.D., Alia Albawardi, M.B.B.S. and @DrTravisBrown on Twitter
Differential diagnosis
- Coccidiodes immitis: smaller spherules (30 - 60 microns), smaller endospores (2 - 5 microns)
- Myospherulosis: large tissue spaces with saclike structures containing brown spherules that resemble Prototheca but are actually clumped red blood cells, GMS-
- Often arthroconidia and hyphae