Diagnosis & Treatment
Rhinosporidiosis is most easily and definitively diagnosed via microscopic observation of the organism on slides from biopsied tissue. The oval-shaped sporangia, containing hundreds of endospores, are easily observable and identifiable under the microscope. In observing similar polyps in the nasal and ocular areas, the presence of white, gray, or yellow dots, which represent the sporangia, are a clear indication of R. seeberi infection. R. seeberi can be visualized using standard microscopic fungal stains, as well as hematoxylin or eosin (H & E) staining. Potassium chloride preparation can also be used to observe the smears (Hospenthal 2002).
Figure 7: H&E stain of an excised polyp showing multiple sporangia filled with endospores (image from Arora et al. 2001)
Rhinosporidiosis cannot be treated with antibiotics, although there have been reports of three patients being treated with dapsone over the course of a year (Venkateswaran et al. 1997). Antimicrobial treatments have proven ineffective, as many of them have been based on an understanding of R. seeberi as a fungus. The only treatment that is known to be clinically successful against rhinosporidiosis is the surgical excision of the polyps (Daniel et al.). Recurrence, although rare, is known to occur in 10% of cases after excision has been performed, and the disease can persist for decades. Excision coupled with electrocoagulation of the base of the lesion now appears to be the treatment of choice in minimizing the risk of recurrence (Hospenthal 2002).
Analysis of the effectiveness of antimicrobial agents on fish or cell lines infected with members of the Dermocystidium genus has the most promise of uncovering successful drug therapy against R. seeberi, due to the close evolutionary relationship between these organisms.