We present a case of a 55-year-old female who presented with an 8-month history of persistent fevers and no other localizing symptomatology. She was worked up extensively for infectious and autoimmune etiologies behind her fevers, but no diagnostic clue was found. The only positive findings were high fT4 and fT3 values with suppressed TSH values. However, the presentation was very atypical for hyperthyroidism. The patient underwent an 18F-FDG PET CT scan which showed increased uptake in the thyroid gland. This evidence combined with the thyroid function test results consolidated the diagnosis of subacute thyroiditis. The patient was managed with nonsteroidal anti-inflammatory agents (NSAIDs) and low-dose steroids. Ten months after the initial presentation, the fevers started to subside, and the patient began experiencing weight gain and cold intolerance. In view of the development of hypothyroid symptoms, the patient was started on levothyroxine 100 mcg once daily. The case is really unique in its unusually long hyperthyroid phase, which in most cases of subacute thyroiditis tends to last no longer than 2–2.5 months. Such a protracted course of 10 months of hyperthyroidism and only pyrexia being the presenting symptom make this case unique.
Singh et al. (2026) studied this question.