A 45-years-old male, with no significant past medical history, presented to the outpatient department with 15-year history of painless neck swelling in the left side and 5-month history of purulent discharging sinus over it. The swelling was slowly progressive in nature and he had mild discomfort while swallowing. There was no complaint of dyspnea or hoarseness of voice. There was no specific history suggestive of hypo- or hyperthyroidism. Though the patient denied any history of fever, he complained of night sweats and loss of appetite. Patient did not have any past history or family history of tuberculosis. Physical examination revealed enlarged left lobe of thyroid (10 x 8 cm) with a single purulent discharging sinus over it with undermined edges. There were no palpable cervical lymph nodes. Pulmonary system examination was normal. Thyroid hormone assay revealed thyroid stimulating hormone (TSH) 2.99 muIU/mL, thyroxine (T4) 9.08 mug/dL, triiodothyronine (T3) 138 ng/dL, thyroglobulin (Tg) 42 ng/mL, thyroglobulin antibody (TgAb) 150 IU/mL, and thyroid peroxidase antibody (TPOAb) 232 IU/mL. Hematological examination revealed hemoglobin 12 g%, hematocrit 42%, ESR 75 mm/first hour, platelets 196000/mm3, and WBC 9300/mm3, with normal differential count. Chest X-ray was normal but Mantoux test was positive (20 x 18 mm). Viral markers test for HIV and anti-HCV was negative. But patient was positive for HbsAg with HbeAg negative and hepatitis B DNA titre of 799 IU/mL. Thyroid ultrasonography revealed enlarged left lobe of thyroid with heterogeneous contents with calcifications. Contrast enhanced computed tomography was performed which showed heterogeneous enhancement of the left lobe of thyroid gland (79 x 95 x 88 mm) with internal vascularity and coarse calcifications. There was a hypodense component with focal air loculi within the lesion (Figure 1). FNAC showed focal necrosis against hemorrhagic background without demonstrable acid fast bacillus (AFB). Culture of the aspirated fluid for mycobacterium tuberculosis came out negative. Core needle biopsy was performed which showed severe chronic inflammation, caseous necrosis, and stain for AFB positive (Figure 2). The patient was put on WHO category 1 antitubercular regime, that is, combination of rifampicin 450 mg, isoniazid 300 mg, ethambutol 1200 mg, and pyrazinamide 1500 mg thrice a week for 2 months. After 2 months, patient had developed progression of swelling with pressure symptoms for which he underwent left hemithyroidectomy.
Grossly, the left thyroid lobe was enlarged measuring 8 x 9 x 8 cm. The cut section was greyish white with extensive areas of autolysis and a cavity identified in the center of the lesion (Figure 3). On histopathological examination, there was destruction of thyroid follicles and extensive fibrosis at the periphery. Numerous lymphoid follicles were seen with lymphocytes infiltrating into the surrounding fibrocollagenous tissue. A 1 cm sinus tract was identified which was lined by dense inflammatory granulation tissue and fibrosis, features suggestive of Hashimoto's thyroiditis (Figure 4) and areas of extensive necrosis adjacent to thyroid follicles suggestive of tuberculosis of thyroid (Figure 5). Final diagnosis of tuberculous thyroid abscess in a background of Hashimoto's thyroiditis in a chronic hepatitis B carrier was made. Postoperatively patient was continued on antituberculous regimen for 9 months.