B72-11 Pulmonary Blastomycosis in a Patient With Progressive Massive Fibrosis: A Diagnostic Challenge

Abstract Introduction Blastomycosis, caused by Blastomyces dermatitidis, is a dimorphic fungus endemic to the Ohio and Mississippi River valleys. The fungus primarily affects the lungs following inhalation of conidia, which evade immune clearance and convert to yeast, inciting granulomatous inflammation (1). Pulmonary blastomycosis often mimics bacterial pneumonia, tuberculosis, or malignancy, complicating timely diagnosis. Radiographic findings are variable, with airspace consolidation being most common; cavitary lesions are rare. Diagnosis becomes particularly challenging in patients with coal workers’ pneumoconiosis, especially in its severe form—progressive massive fibrosis (PMF)—which features large fibrotic masses that may cavitate. Case Presentation A 67-year-old male with a history of OSA, COPD, hypertension, and pneumoconiosis with PMF presented to the pulmonology clinic with chronic exertional dyspnea, cough with thick clear sputum, and paroxysmal nocturnal dyspnea. He denied orthopnea, fever, night sweats, or hemoptysis. Chest CT revealed mass-like opacifications and scattered nodules consistent with PMF, along with an irregular cavitary consolidation in the posterior right infra hilar region extending to the superior segment of the right lower lobe. Bronchoscopy was performed, and fungal cultures from bronchial washings grew Blastomyces dermatitidis. The patient was started on oral itraconazole. Discussion This case underscores the diagnostic complexity of pulmonary blastomycosis in the setting of PMF. The patient’s known occupational lung disease and chronic symptoms initially suggested progression of PMF. However, the emergence of cavitary lesions raised concern for superimposed infection. Radiographic manifestations of blastomycosis are diverse, ranging from airspace and lobar consolidation to diffuse interstitial changes (2). Cavitary lesions, though uncommon, should prompt consideration of fungal etiologies, especially in endemic areas. The overlap in imaging findings between PMF and fungal infections can obscure diagnosis, delaying appropriate treatment. Conclusion Blastomycosis should remain a differential consideration in patients with occupational lung disease presenting with new cavitary lesions, particularly in endemic regions. Early recognition and antifungal therapy, typically with itraconazole, are essential to prevent complications. Amphotericin B may be reserved for severe or disseminated disease. This case highlights the importance of maintaining a broad differential and utilizing bronchoscopy and fungal cultures for definitive diagnosis. Reference: 1. Maini R, Ranjha S, Tandan N, et al. Pulmonary blastomycosis: a case series and review of unique radiological findings. Med Mycol Case Rep. 2020;28:49-54. doi:10.1016/j.mmcr.2020.03.006.2. Fang W, Washington L, Kumar N. Imaging manifestations of blastomycosis: a pulmonary infection with potential dissemination. Radiographics. 2007;27(3):641-655. doi:10.1148/rg.273065122. This abstract is funded by: none