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Tissue morphology of Histoplasma capsulatum in acute histoplasmosis
Abstract:
Reports of histopathology in acute histoplasmosis are rare. A case of fulminating acute histoplasmosis with hematogenous dissemination is described in which Histoplasma capsulatum was identified in transbronchial biopsy. This report represents the first morphologic description of H. capsulatum within human pulmonary tissue in the early phase of acute histoplasmosis. The yeast forms observed were of typical size, but they were present within the alveoli and were budding. No tissue granulomata were noted. This unusual morphology is in sharp contrast to the classic description of the organism in tissues and presented diagnostic difficulties, which are discussed in this report. Hematogenous dissemination is considered to be an important part of the pathogenesis of the disease, but it is rarely documented during the symptomatic phase of acute histoplasmosis. Cultural documentation of hematogenous dissemination was obtained in this patient. These observations stress the importance of obtaining culture material from extrapulmonary sites early in the course of acute histoplasmosis when a specific diagnosis is necessary.
Insights
This study details a rare case of acute histoplasmosis, identifying Histoplasma capsulatum in lung tissue. Early diagnosis is crucial, highlighting the need for cultures from extrapulmonary sites.
Area of Science:
- Medical Mycology
- Pulmonary Pathology
- Infectious Diseases
Background:
- Acute histoplasmosis is a fungal infection caused by Histoplasma capsulatum.
- Histopathology findings in acute histoplasmosis are infrequently reported.
- Hematogenous dissemination is a known but rarely documented aspect of acute histoplasmosis pathogenesis.
Observation:
- A rare case of fulminating acute histoplasmosis with hematogenous spread is presented.
- Histoplasma capsulatum was identified in a transbronchial biopsy of pulmonary tissue.
- Unusual yeast morphology was observed within alveoli, lacking granulomata, differing from typical descriptions.
Findings:
- This report provides the first morphologic description of Histoplasma capsulatum in early-phase human pulmonary tissue.
- The observed yeast forms exhibited atypical intracellular budding within alveoli.
- Hematogenous dissemination was confirmed by culture from extrapulmonary sites during the symptomatic phase.
Implications:
- The atypical morphology of Histoplasma capsulatum in early acute disease can pose diagnostic challenges.
- Early culture of extrapulmonary specimens is vital for diagnosing acute histoplasmosis, especially with disseminated disease.
- Understanding early-phase histopathology aids in timely and accurate diagnosis of disseminated fungal infections.