Anaerobic thyroid abscess from a thyroid cyst after fine-needle aspiration

Background. Anaerobic abscess formation within a thyroid cyst is rare but still possible, although aerobic thyroid abscess formation in the thyroid gland after fine-needle aspiration (FNA) has been observed in immunocompromised patients. Methods. This study describes the clinical manifestations, thyroid echography, cytologic finding, culture outcome, and treatment course of an anaerobic abscess formation within a thyroid cyst after FNA in a healthy subject. Results. A 53-year-old male subject had rapid enlargement of a left thyroid cyst develop after second FNA. Frank pus was obtained through third FNA. The culture outcome was Propionibacterium acnes, which was rich in saliva and one of the pathogens causing periodontitis and gingivitis. After adequate antimicrobial therapy, the abscess gradually diminished. Conclusions. This article reported, for the first time, on the formation of an anaerobic thyroid abscess after FNA in a healthy subject. We recommended careful aseptic procedure and adequate isolation processes, such as wearing a mask to avoid an unfavorable outcome as a result of a bacterial infection.