Cell-mediated immune responses (CMIR) in human rhinosporidiosis

Case Report: Rhinosporidiosis, Case Report, and Literature Review

Rhinosporidiosis is caused by Rhinosporidium seeberi, a pathogen currently considered a fungus-like parasite of the eukaryotic group Mesomycetozoea. It is usually a benign condition, with slow growth of polypoid lesions, with involvement of the nose, nasopharynx, or eyes. The clinical characteristics of a painless, friable, polypoid mass, usually unilateral, can guide the diagnosis, but the gold standard for diagnosis is histopathological findings. This article reviews the epidemiology, pathobiology, clinical manifestations, diagnostic strategies, and treatment approach for rhinosporidiosis.

Rhinosporidiosis of the parotid duct

Rhinosporidiosis is a benign chronic granulomatous infection caused by Rhinosporidiosis seeberi (R. seeberi). Rhinosporidiosis is endemic in South Asia, notably in Southern India and Sri Lanka. The common sites of involvement are the nose and nasopharynx followed by ocular tissue. Rhinosporidiosis is also known to involve many rare sites and may become disseminated to ocular in generalized form. Rhinosporidiosis of parotid duct is extremely rare. The case presented here is of 18-year-old male from the nonendemic zone of Nepal with a proliferative mass in the parotid duct. Although rhinosporidiosis was not taken into consideration in the clinical differential diagnosis, eventual histopathological diagnosis confirmed rhinosporidiosis. Thus clinicians should be flexible in the differential diagnosis of proliferative growth in the parotid duct, even in those cases which are from nonendemic areas.

Rhiinosporidiosis - unusual presentations

Rhinosporidiosis is an infection caused by Rhinosporidium seeberi that frequently presents as polypoidal nasal lesions. Here, we report two cases of rhinosporidiosis with unusual presentations. The first case presented in our department with chronic dacryocystitis of left side for endoscopic dacryocystorhinostomy (endoscopic DCR) operation. The second case presented as a long hanging mass arising from the right side of nasal septum. The diagnosis was established on the morphological basis by the identification of endospores and sporangia. The clinicopathological and immunologic features were discussed and the literature was reviewed.

Tropical dermatology: fungal tropical diseases

Fungal infections are common in tropical countries and can have an important impact on public health. Lobomycosis is a common fungal infection in the tropical rain forest of South America, and paracoccidioidomycosis (South American blastomycosis) is a widespread and sometimes severe illness. Penicilliosis marneffei is an opportunistic infection of AIDS patients in southeast Asia. Chromoblastomycosis and mycetomas are causes of morbidity around the world. Sporotrichosis is a worldwide subcutaneous mycosis with a high incidence in tropical countries and is an important illness in immunocompromised patients. Rhinosporidiosis was classed as a fungal infection but is now considered a protistan parasite that belongs to the class Mesomycetozoea. It is included in this review because of its historical classification. In the past, most of these mycoses were restricted to specific geographic areas and natural reservoirs. There are, however, situations in which people from other regions come in contact with the pathogen. A common situation involves an accidental contamination of a traveler or worker who has contact with a tropical mycosis. Even minor trauma to the skin surface or inhalation of the fungal conidia can infect the patient. Thus recognition of the clinical symptoms and the dermatologic findings of the diseases, as well as the geographic distribution of the pathogens, can be critical in diagnosis of the tropical mycoses. This review discusses some of the more common tropical subcutaneous and systemic mycoses, as well as their signs, symptoms, methods of diagnosis, and therapies.

LEARNING OBJECTIVE

At the completion of this learning activity, participants should be able to recognize the clinical and histologic presentations of tropical fungal diseases with cutaneous manifestations and be familiar with the appropriate therapies.

Rhinosporidiosis in Egypt: a case report and review of literature

Rhinosporidiosis is an infection caused by Rhinosporidium seeberi that frequently presents as a polypoidal nasal lesions. Here, we report the first indigenous case of tumoral rhinosporidiosis in Egypt. In this case, a 25-year-old male patient from a rural background of Assuit City presented with epistaxis and a nasal polyp. The patient had not traveled abroad. The diagnosis was established on the morphological basis by the identification of 5- to 10-microm endospores and 50- to 1000-microm sporangia. The clinicopathological and immunologic features were discussed and the literature was reviewed. To the best of our knowledge this is the first case of this disease to be reported in Egypt in the human literature.

Rhinosporidiosis: what is the cause?

PURPOSE OF REVIEW

Significant advances in knowledge on rhinosporidiosis and Rhinosporidium seeberi were made in 1999, 2000, 2003 and 2004. These advances are reviewed on account of the continuing sporadic occurrence of the disease universally, and because of the availability of new approaches that could resolve persisting enigmas of both the disease and its causative pathogen.

RECENT FINDINGS

R. seeberi, the pathogen that causes rhinosporidiosis, has been definitively classified using molecular biological tools in a new clade - the Mesomycetozoea, along with 10 parasitic and saprobic microbes. The controversial spherical bodies of the endospores have been shown to comprise both lipid/protein nutritive bodies and other spherical bodies that are metabolizing units that reduce MTT (3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium bromide). This indicates the viability of these spherical bodies, provisionally identified as the electron dense bodies that have also been shown to contain nucleic acids. MTT reduction as an indicator of viability has been used to determine the sensitivity of rhinosporidial endospores to biocides, antimicrobial drugs, and to specific antibodies. Genetic heterogeneity has been identified in strains from humans and animals. Cell-mediated and humoral immune responses have been demonstrated in human patients and in mice. Several mechanisms of immune evasion by R. seeberi have been identified.

SUMMARY

These findings are applicable in both clinical and laboratory practice, while the basic advances have implications in further work on experimental pathogenicity, the biology of R. seeberi, and on the epidemiology and pathogenesis of rhinosporidiosis.