Thyroid Abscess After FNA Biopsy: A Case Report

Introduction: FNA biopsy of thyroid nodules is a common bedside procedure that rarely causes serious complications. Thyroid abscess is a rare complication of FNA that requires prompt diagnosis and treatment. We present a case of a thyroid abscess occurring 4 weeks after FNA in a 46 year old female, treated successfully with surgery. Clinical Case: A 46 year old woman with history of acne presented with dysphagia, right sided neck pain and swelling 4 weeks after FNA of a 4.8cm right thyroid nodule with benign cytology. On physical examination, the right thyroid lobe appeared larger and was tender to palpation. The patient was afebrile. Laboratory evaluation was significant for acutely low TSH 0.06 uIU/mL [0.50 - 6.00 uIU/mL], thrombocytosis 547 K/uL [140 - 400 K/uL] and marked elevated sedimentation rate 98 mm/hr [0 - 20mm/hr]. Interestingly, she had a normal leukocyte count of 9.8 K/uL [4.00 - 10.80 K/uL]. US imaging showed acute increase in size of the right thyroid nodule to 7.6cm. CT neck confirmed a large, partially cystic right thyroid mass and further showed mass effect on surrounding structures and mild stranding in the subcutaneous fat. The patient elected for surgical treatment rather than repeat FNA with drainage of fluid components. Right thyroid lobectomy was planned but converted to surgical abscess drainage with subtotal thyroidectomy due to intense inflammatory changes in the neck. A large amount of purulent material was drained and sent for cultures, which grew multiple Staphylococcus species and Propionibacterium acnes. Surgical pathology showed granulation and connective tissue including skeletal muscle tissue with marked active chronic inflammation, micro abscess formation, few multinucleated giant cells, and fibrosis. Following surgery, TSH normalized, and the patient reported immediate improvement in symptoms of neck fullness, pain, and dysphagia. She was discharged home on post operative day one with a two week course of oral Augmentin 875mg twice daily. 6 weeks post operatively the patient remains symptom free in her usual state of health. Conclusion: Thyroid abscess following FNA is a rare occurrence with few reported cases in the literature. Because of its rarity, diagnosis and treatment may be delayed, resulting in a life-threatening emergency. Both repeat needle aspirations and surgical management, combined with culture directed antibiotics, are acceptable methods for treatment. Immunocompromise, not present in our patient, is the main risk factor reported for thyroid abscess. Propionibacterium and Staphylococcus commonly cause acne, which may have increased our patient’s risk of infection. Our case highlights the importance of maintaining a high level of clinical suspicion for abscess in patients who develop neck pain and swelling following FNA, even in the absence of significant risk factors, in order to facilitate prompt diagnosis and treatment.