Diffuse Pulmonary Nodules due to Histoplasmosis: Case Report with Review of Literature

Author(s):
Ian Whittall; Jonathan Nakata; Stacey Su

Background:

Bilateral pulmonary histoplasmosis is a rare infectious process caused by Histoplasma capsulatum. Most individuals are asymptomatic or develop insidious pulmonary symptoms. However, significant morbidity and mortality are common and require prolonged antifungal therapy. We present an immunocompetent patient diagnosed with bilateral pulmonary histoplasmosis.

Hypothesis:

Not applicable.

Methods:

A 54-year-old female with diabetes mellitus presented with 4 months of mild exertional dyspnea. She denied smoking, environmental, or occupational exposures. Chest CT (Fig. 1) revealed innumerable miliary pulmonary nodules and hilar lymphadenopathy. PET scan demonstrated mildly active, multifocal pulmonary nodules and mediastinal lymphadenopathy. No evidence of systemic disease was present. Subsequent endobronchial ultrasound with biopsy of lymph nodes and bronchoalveolar lavage was non-diagnostic. Left upper lobe wedge resection was performed for definitive tissue diagnosis. Grossly, the tissue had multiple firm tan-pink nodules. Pathologic review demonstrated caseating granulomas with histoplasma-like organisms and positive Grocott stain. On follow-up, she was asymptomatic and was not started on antifungal therapy.

Results:

Not applicable.

Conclusions:

Histoplasmosis predominantly affects immunocompromised individuals in endemic regions with occupational or environmental factors that increase exposure to Histoplasma spores. Initial presentation is often asymptomatic but can develop into pulmonary disease or disseminated infection. Histoplasma causes non-specific granulomatous inflammation similar to more common granulomatous disease processes, such as sarcoidosis or tuberculosis. However, when initial non-invasive testing is non-diagnostic, bronchoscopic or surgical tissue biopsy may be needed. Treatment for isolated pulmonary disease is guided by symptom severity and duration. Chronic disease and moderate or severe acute disease merit antifungal treatment to avoid progressive loss of pulmonary function. The adverse effects of antifungal therapy and the relative lack of long-term morbidity associated with mild pulmonary disease indicate conservative management in these patients.