An 18-year-old Malay female, previously well, presented with one-week history of right sided painful neck swelling, fever, and odynophagia. Preceding this she denied any acute pharyngitis, constitutional symptoms, night sweats, or TB contacts. There were no hyper or hypothyroid symptoms. She denied any history of trauma to the neck. Clinical examination revealed a blood pressure of 118/72 mm Hg, pulse rate 89 bpm, and temperature 37 C. She was euthyroid, no orbitopathy or other evidence of Grave's disease. There was a right anterolateral neck mass measuring 4 x 5 cm, mild warmth and tender to palpation, however no fluctuant area. There was no cervical lymphadenopathy.
Laboratory investigations showed leucocytosis TWBC 17.6 x 10/L with neutrophil predominance and elevated inflammatory markers ESR 98 mm/hour, CRP 105.8 mg/L (<5.0). Negative HIV screening and fasting glucose of 5.1 mmol/L ruled out immunocompromised state. Her baseline thyroid function test (TFT) upon admission was TSH 0.13 mU/L (0.56-4.90) and FT4 21.1 pmol/L (1.5-22.7). Chest X-Ray showed clear lung fields. Neck ultrasound demonstrated heterogenous appearance of both thyroid lobes, with heterogenous hypoechoic mass occupying the right lobe, extending towards the left isthmus-thyroid junction (Figures 1A and 1B). Contrast-enhanced computer tomography (CECT) of the neck showed a multiloculated hypodense rim enhancing collection with the epicentre in the right thyroid lobe measuring collectively 3.5 x 4.6 x 5.4 cm. Posterosuperiorly, there was an extracapsular extension of the collection into the prevertebral space which measures 5.5 cm in craniocaudal length from the level of C2/3 until C6/7 with displacement of trachea to the left. In addition, there were multiple enhancing bilateral cervical lymph nodes in all levels, with the largest measuring 0.9 x 0.6 cm (Figures 2A and 2B). Fibreoptic laryngoscope showed patent airway and no pyriform sinus fistula. A repeat TFT three days after iodinated contrast media (ICM) exposure noted markedly elevated TFT almost three times upper limit with TSH of 0.098 mU/L (0.900 - 3.110) and FT4 36.3 pmol/L (7.8 - 13.2), suggestive of contrast induced thyroiditis. Hence, no anti-thyroid treatment was initiated.
She underwent a bedside fine needle aspiration which aspirated 5 cc of frank pus and a repeat ultrasound guided aspiration which aspirated 25 cc of pus. However, a repeat ultrasound showed persistence of the remaining collection at right thyroid bed thus a decision to proceed with right hemithyroidectomy and incision and drainage of right parapharyngeal abscess. Intra-operatively, the right thyroid gland weighed 12 g, the superior pole was found to be sloughy and adhering to the strap muscles. A total of 5 cc of pus was aspirated from the thyroid gland and parapharyngeal area. A drainage catheter was inserted and kept for six days which drained 10 - 30 mls of pus daily.
Pus and tissue cultured Streptococcus anginosus and Eikenella corrodens both sensitive to penicillin G. Polymerase chain reaction (PCR) of the pus was also positive for Mycobacterium tuberculosis despite the acid-fast bacilli (AFB) smear being negative. However, pus and tissue culture did not isolate any mycobacterium tuberculosis (MTB). Tissue histopathological examination (HPE) demonstrated xanthogranulomatous inflammation with microabscess formation. No epithelioid histiocytes, granuloma formation nor Langhan's giant cells was seen. Sputum smear for acid fast bacilli sent twice were negative. She was discharged with oral Ampicillin plus Sulbactam 750 mg twice daily for four weeks (total duration six weeks) and combination of Isoniazid 75 mg, Rifampicin 150 mg, Ethambutol 275 mg and Pyrazinamide 400 mg, four tablets once daily based on the initial TB PCR result. A follow-up ultrasound neck five weeks after commencement of antibiotics and 18 days after initiation of anti-TB did not show any residual abscess collection. Outpatient TFT performed four weeks post-surgery indicate recovering TFT with TSH of 0.74 mIU/L (0.46-4.68) and FT4 6.8 pmol/L (10.0-28.2) without any anti-thyroid medication.