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Rhinosporidiosis: immunohistochemical and electron microscopic studies
B Azadeh1, N Baghoumian, O T el-Bakri
1Department of Pathology, Hamad General Hospital, Doha, State of Qatar.
Abstract:
Sixteen biopsies of rhinosporidiosis (15 nasal and one conjunctival) from 16 Southern Indian male immigrant workers showed mucosal lymphoplasmacellular infiltrates together with transepithelial elimination of nodular bodies and destruction of some late stage nodular bodies in histiocytic granulomata with central neutrophilic microabscesses. Early nodular bodies were immunohistochemically positive for alpha 1-AT, alpha 1-ACT, CEA, S100, fibronectin, amyloid-p-component, IgG, IgA, C1q and C3. Electron microscopy showed organized concentric lamellated bodies in early nodular bodies and not in end-stage nodular bodies which contained mostly amorphous electron dense materials. Structures formerly regarded as 'sporangia' and 'spores' are believed to be lysosomal bodies loaded with indigestible residues to be cleared via transepithelial elimination or segregated/destroyed by secondary immune/granulomatous responses.
Insights
Rhinosporidiosis involves immune responses that eliminate and destroy fungal nodular bodies. These structures, previously termed
Area of Science:
- Pathology
- Immunology
- Mycology
Background:
- Rhinosporidiosis is a chronic granulomatous infectious disease.
- The exact nature of rhinosporidial 'spores' and 'sporangia' remains debated.
- Understanding the host-pathogen interaction is crucial for rhinosporidiosis management.
Purpose of the Study:
- To investigate the histopathological and immunohistochemical characteristics of rhinosporidiosis.
- To elucidate the nature of rhinosporidial bodies and their elimination mechanisms.
Main Methods:
- Histopathological examination of 16 rhinosporidiosis biopsies.
- Immunohistochemical analysis of early nodular bodies.
- Electron microscopy of early and end-stage nodular bodies.
Main Results:
- Mucosal biopsies showed lymphoplasmacellular infiltrates and granulomata.
- Early nodular bodies were immunohistochemically positive for various proteins including alpha 1-antitrypsin (alpha 1-AT) and complement components (C1q, C3).
- Electron microscopy revealed organized lamellated structures in early bodies and amorphous material in end-stage bodies.
Conclusions:
- Rhinosporidial 'spores' and 'sporangia' are likely lysosomal bodies containing indigestible residues.
- Transepithelial elimination and immune responses are key mechanisms for clearing these bodies.
- The findings provide new insights into the pathogenesis of rhinosporidiosis.