Disseminated blastomycosis diagnosed by fine‐needle aspiration of the thyroid

Abstract

Blastomycosis is an uncommon disease caused by the dimorphic fungus Blastomyces dermatitidis. It can manifest as chronic pulmonary symptoms or disseminated disease. Only three previous cases of blastomycosis involving the thyroid have been reported, of which two were diagnosed by fine-needle aspiration. We present a case of disseminated blastomycosis initially diagnosed by thyroid fine-needle aspiration. Our case was a 47-year-old man with past medical history significant for diabetes, hyperlipidemia, and chronic pancreatitis who presented with a 2-week history of fever, chills, rigors, constipation, and 10 pound weight loss. Abdominal CT revealed chronic pancreatitis and a calcified mass in the pancreas. Chest CT revealed a single 1.5-2 cm thyroid mass and innumerably small 2-3 mm pulmonary nodule bilaterally. Fine-needle aspiration of the thyroid demonstrated 10-20 μm broad-based budding yeasts with thick-walled, refractile capsules amidst a background of granulomatous inflammation, and was diagnosed as a fungal infection consistent with blastomycosis. The patient was started on treatment with itraconazole based upon the FNA diagnosis. Concurrent lung biopsy demonstrated rare possible yeast forms on histology. A specimen from the lung was sent for culture, and was positive for B. dermatitidis, confirming the diagnosis. Disseminated blastomycosis rarely involves the thyroid. However, the thyroid is amenable to fine-needle aspiration. Fungal and mycobacterial cultures and special stains for fungal organisms should be requested on all thyroid fine-needle aspiration biopsies with granulomatous inflammation.

Thyroid fine-needle aspiration of an immunocompromised patient: Cytomorphological clues

“…(c) Diagnostic methods for Coccidioides infection typically include serology for antibodies, microbiological culture, and histopathology with special stains. [123] FNA has proven to be a rapid and effective diagnostic procedure of infectious lesions. Some studies emphasize that FNA is an effective diagnostic tool, and clinicians need to be aware of the unique advantages of FNA in the diagnosis of coccidioidomycosis.…”

“…The rare cases of Blastomyces and Cryptococcus of the thyroid gland have been reported. [23] Blastomyces are broad-based budding organisms (like “snowman”) and have thick cell walls. Cryptococcus is characterized by a single teardrop-shaped budding with a thick mucoid capsule, which can be highlighted by mucicarmine stain.…”

Role of fine needle aspiration biopsy cytology in the diagnosis of infections

“…It causes pneumonia especially in AIDS patients and disseminates to lymph nodes, spleen, and bone marrow. 1,2,[29][30][31] It is a dimorphic fungus and usually is associated with suppuration with or without necrotizing granulomas. 1,2 The cysts aggregate into foamy casts of the bronchi, eosinophilic in the Pap or purple in the Giemsa stains.…”

Pathology Quiz Case 2: Diagnosis

“…1 The most common sites of dissemination to the head and neck region include the skin, larynx, oral and nasal mucosa, and thyroid. [2][3][4][5] Blastomyces dermatitidis is endemic to the Ohio River and Mississippi River basins of North America as well as to watershed areas that border the Great Lakes, including Canada. 1 Hyperendemic areas include Wisconsin, where our patient lived.…”

“…4 In the few reported cases of thyroid involvement, blastomycosis presented as a thyroid mass with evidence of nonnecrotizing granulomatous inflammation seen on a fine-needle aspirate. 3 Definitive diagnosis of blastomycosis is the pathognomonic appearance of broad-based buds of multinucleate yeast on specimens obtained at the specific site of disease presentation. 1 Histologically, B dermatitidis appears as a 5-to15-µm thick-walled spherical yeast with broadbased budding daughter cells.…”