Synonyms
DefinitionRhinosporidiosis is an infectious disease caused by an aquatic protozoan previously considered to be a fungus [766]. The etiologic agent of rhinosporidiosis, Rhinosporidium seeberi, is closely related to several protoctistiae fish pathogens. The infection affects nasal mucous membranes and ocular conjunctivae of humans and animals, producing slowly growing masses that degenerate into polyps. The symptoms vary depending upon the stage of tumor development and site infected. The polyps are usually pink to purple and friable [1556, 2285].
Ocular Rhinosporidiosis
GMS stain of tissue infected with Rhinosporidium seeberi
Forms of the disease
Nasal
Ocular
Cutaneous
Disseminated (rare)
Prognosis and therapy
The polyps are chronic but not painful. Surgical removal of polyps by hot or cold snare techniques are utilized in order to minimize recurrence [1556]. Local injection of amphotericin B may be helpful. Dapsone seems to be a good alternative [1125, 1609].
Histopathology
Large numbers of well defined cysts typically lie just beneath the hyperplastic epithelium. In tissue the organism forms large sporangia approaching 300 um in diameter that contain spores that mature at different rates. Mature sporangiospores are approximately 7-9 um in size and escape through a pore that develops in the sporangial wall. The tissue response is a polymorphonuclear inflammatory reaction with abscess formation, and some tissue necrosis. Granulation tissue and scarring are usually prominent.
Laboratory
Direct examination
Excised macerated tissue or nasal discharge is mounted in 10% KOH for examination. Spherules and large numbers of free endospores are typically present.
Isolation
The organism has not been cultured.
Natural Habitat
Unknown