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Progressive disseminated histoplasmosis in an apparently immunocompetent patient with a bioprosthetic aortic valve
Anthony Lieu1, Leighanne O Parkes1,2,3, Yves Longtin1,2,3
1Department of Medicine, McGill University, Montréal, Québec, Canada.
Abstract:
Histoplasma capsulatum is an endemic fungus in eastern Canada. This organism has a wide spectrum of manifestations ranging from isolated pulmonary to disseminated disease. The latter usually occurs in immunocompromised hosts or those with substantial environmental exposure. In rare instances, disseminated histoplasmosis can present as an endovascular infection or chronic progressive disseminated histoplasmosis. If not recognized, these entities are almost uniformly fatal. We report a case of an immunocompetent man with a history of longstanding constitutional symptoms. An infectious cause was initially presumed to be unlikely given the chronic nature of his presentation and an extensive series of negative investigations. A diagnosis was only obtained post-mortem upon the unusual detection of both yeast and hyphal forms in blood culture bottles inoculated with a bone marrow aspirate.
Insights
Histoplasma capsulatum, endemic in eastern Canada, can cause severe disseminated disease, even in immunocompetent individuals. Post-mortem diagnosis in a chronic case highlights the importance of considering this fungal infection.
Area of Science:
- Mycology
- Infectious Diseases
- Clinical Pathology
Background:
- Histoplasma capsulatum is endemic in eastern Canada, presenting diverse clinical manifestations.
- Disseminated histoplasmosis typically affects immunocompromised individuals or those with significant exposure.
- Rarely, it can manifest as endovascular infection or chronic progressive disseminated disease, often fatal if unrecognized.
Observation:
- A case of an immunocompetent male with prolonged constitutional symptoms was investigated.
- Initial investigations were extensive but negative, deeming an infectious etiology unlikely due to the chronic presentation.
- Diagnosis was confirmed post-mortem via detection of yeast and hyphal forms in blood cultures from bone marrow aspirate.
Findings:
- The study highlights a rare case of disseminated Histoplasma capsulatum in an immunocompetent host.
- Chronic, insidious presentation mimicked other conditions, delaying diagnosis.
- Post-mortem blood culture revealed both yeast and hyphal forms, confirming disseminated fungal infection.
Implications:
- This case underscores the potential for severe, atypical presentations of Histoplasma capsulatum in immunocompetent individuals.
- It emphasizes the need for broader diagnostic considerations in chronic, unexplained constitutional symptoms.
- Timely recognition and treatment are critical for improving outcomes in disseminated histoplasmosis.
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