Case Presentation: A 35-year-old man with no significant past medical history was admitted for evaluation of newly identified cavitary lung disease. His illness started 3 months prior to the presentation with high grade fever lasting two weeks, followed by progressive nausea, vomiting, dry cough, malaise, night sweats, anorexia, and an unintentional 11% weight loss. His travelled to Alaska shortly before the onset of symptoms and had a Caribbean cruise earlier in the year. He worked as a carpenter. CT imaging revealed numerous bilateral noncalcified pulmonary nodules, several of which are cavitary, mediastinal and hilar lymphadenopathy and mild splenomegaly. Given the cavitary lesions and systemic symptoms, tuberculosis was a leading diagnostic consideration. Coccidioidomycosis (“valley fever”) was also considered based on occupation and travel history.Infectious workup was initiated, including sputum AFB smear and culture, MTB complex PCR, Quantiferon-TB Gold, and serologic testing for fungal pathogens including Blastomyces, Histoplasma, Coccidioides, and Aspergillus. Blood and bronchial culture were obtained. Infectious Disease and Pulmonology were consulted. Airborne precaution maintained until tuberculosis was excluded. Bronchoscopy with bronchoalveolar lavage was performed. Transbronchial biopsies from the right upper lobe and mediastinal lymph nodes showed no evidence of malignancy or granulomatous inflammation. Blastomyces antibody testing returned positive, and although Blastomyces immunodiffusion was negative, a single negative result does not rule out the diagnosis of blastomycosis. The remainder of the evaluation was unrevealing. The patient was started on itraconazole 200 mg every eight hours, with subsequent clinical improvement. He was discharged with close outpatient Infectious Disease follow-up. The treatment duration is expected to be 6 to 12 months based on clinical response.
Discussion: Blastomycosis is a systemic pyogranulomatous infection caused by the dimorphic fungi Blastomyces dermatitidis and gilchristii, typically found in moist soil and decaying vegetation. Infection occurs through inhalation of airborne conidia. Pulmonary blastomycosis ranges from asymptomatic or mild, self-limited respiratory illness to acute or chronic pneumonia, and in severe cases, acute respiratory distress syndrome (ARDS). Extrapulmonary dissemination most commonly involve the skin, bone, or genitourinary tract. We present an uncommon case of blastomycosis in which a young, immunocompetent man developed cavitary pulmonary lesions closely mimicking tuberculosis and malignancy. This case highlights the diagnostic complexity and the pivotal role of the hospitalist in identifying fungal etiologies.
Conclusions: Blastomycosis is an uncommon, with annual incidence of 0.2 to 1.94 cases per 100,000 persons, and often mimics tuberculosis and malignancy. Early recognition is challenging, particularly in immunocompetent individuals. Radiographic features including bilateral cavitary nodules and lymphadenopathy overlap with tuberculosis, leading to potential diagnostic delays. This case underscores the importance of maintaining a broad differential diagnosis for cavitary lung disease, especially in patients with environmental exposures or travel to endemic regions within the preceding two years. Early serologic testing for endemic fungi and prompt initiation of antifungal therapy can significantly reduce morbidity.
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