A RARE PRESENTATION OF THYROID CANCER IN YOUNG ADULT, WITH CONCOMITANT SUBCLINICAL HYPERTHYROIDISM

Abstract

INTRODUCTION
Thyroid malignancy is uncommon in children and adolescents. It accounts for 1.5 to 3% of all carcinomas in this age group. Thyroid cancers are rarely associated with thyroid hyperfunction. The incidence of this co-incidence is highly variable, reported to be as low as 0.15%.

CASE
A previously healthy 19-year-old woman presented with one day history of neck swelling and sore throat. She was clinically euthyroid. Review after 2 weeks showed a persistent mass, consistent with thyroid nodule. Examination showed a blood pressure of 112/74, heart rate of 80 beats/minute and normal body temperature. Her body mass index was 21 kg/m2. There was a palpable 3 cm x 3 cm non-tender right thyroid nodule with no palpable lymph nodes. Thyroid function test (TFT) revealed subclinical hyperthyroidism on 2 separate occasions [thyroxine (T4) 13.8 and 15.5 pmol/L, thyroid stimulating hormone (TSH) 0.49 and 0.39 mIU/L, respectively]. Anti-thyroid peroxidase and antithyroglobulin were both negative. Ultrasonography (US) of the thyroid showed multiple suspicious solid hypoechoic right thyroid nodules with microcalcification and increased vascularity, with the largest nodule measuring 2.7 cm x 1.5 cm with mixed solid and cystic appearance. US-guided fine needle aspiration (FNA) biopsy showed benign colloid nodule with degeneration. In view of the subnormal TSH, she underwent thyroid uptake scan which revealed non-toxic multinodular goitre with a cold nodule in the lower pole of the right thyroid lobe, corresponding to a hypodense solid lesion on computerised tomography, and no uptake at the surrounding lymph nodes. Repeated US-guided FNA cytology of the corresponding cold nodule was read as papillary thyroid carcinoma Bethesda 5. She underwent hemithyroidectomy. Intra-operative histopathology concurred with welldifferentiated papillary thyroid carcinoma.

CONCLUSION
This was a common case with an uncommon presentation. Thyroid malignancy is uncommon in children and adolescents. The slow growing nature of a thyroid carcinoma would give a subtle rather than acute presentation. Subclinical hyperthyroidism is usually associated with hyperfunctioning of the thyroid gland rather than malignancy.