Disseminated Blastomycosis Mimicking Metastatic Head and Neck Cancer in a 70-year-Old Man.

Blastomycosis is a fungal infection known to mimic many disease processes, including malignancy. A 70-year-old man presented with an enlarging neck mass and, incidentally found on preliminary imaging, a lung mass. The initial biopsy of the neck mass demonstrating cytologic atypia and mitotic figures was suggestive of malignancy. Whole body positron emission tomography (PET)/CT revealed hypermetabolic lesions in multiple sites, including the neck, lung, and soft tissue, raising concern for metastatic disease. Repeat sampling from multiple lesions, however, demonstrated granuloma. Microbiological studies were collected, and Blastomyces dermatitidis was isolated in culture. The diagnosis of disseminated blastomycosis was made, and the patient received antifungal therapy with good response. A high degree of suspicion for blastomycosis in endemic areas is required to ensure patients receive appropriate and timely treatment. Laryngoscope, 133:2237-2239, 2023.