Anaplastic thyroid cancer with transient thyrotoxicosis: Case report and literature review

A 55-year-old woman with anaplastic thyroid carcinoma presented with hypert hyroidism and neck swelling, hoarseness, and cervical lymphadenopathy. On p hysical examination, she was found to be clinically hyperthyroid with an en larged, nontender multinodular goitre. Her serum thyroid hormone levels con firmed hyperthyroidism and technetium-99m pertechnetate scan failed to visu alize the thyroid gland. Open biopsy showed an invasion of the thyroid glan d by anaplastic thyroid carcinoma. The thyrotoxic phase lasted 60 days with predominantly increased thyroxine level and triiodothyronine/thyroxine (T- 3/T-4) ratio decreased below 15. The thyrotoxic period was followed by subc linical hyperthyroidism and hypothyroidism which continued until she died o f lung metastasis.