Fine-needle aspiration diagnosis of thyroid blastomycosis.

Objective: To describe an elusive case of blastomycosis involving the thyroid gland, which was ultimately diagnosed by use of ultrasound-guided fine-needle aspiration (FNA).

Methods: We present a case report, including clinical features, results of laboratory studies, and radiographic, computed tomographic, and ultrasonographic findings. In addition, the treatment and the utility of FNA of the thyroid relative to the diagnosis of blastomycosis are discussed.

Results: An 18-year-old woman with no significant past medical history and with a competent immune system presented initially to her family physician because of headaches, lymphadenopathy, blurry vision, and fatigue. Radiography of the chest showed findings considered consistent with pneumonia, for which amoxicillin was prescribed. Subsequently, an ophthalmologist diagnosed anterior uveitis and initiated topical corticosteroid therapy. Worsening symptoms prompted performance of computed tomography of the chest, which suggested thyroid involvement. Ultimately, FNA of a thyroid nodule led to the cytologic diagnosis of blastomycosis. The patient was treated successfully with amphotericin for blastomycosis of the eye, lung, and thyroid.

Conclusion: Physicians should consider the potential presence of blastomycosis when a lung lesion does not improve with typical treatment interventions. Disseminated blastomycosis can be diagnosed with use of FNA of the thyroid.