A case series and literature review of thyroid cancer presenting with thyroid hot nodule.

Thyroid nodules are commonly found in clinical practice, with a prevalence of 5%-7% on physical examination and up to 20%-67% when detected by high-resolution ultrasound in adults. The annual incidence of thyroid cancer varies significantly in different countries, ranging from 2.0 to 3.8/100,000 in women and from 1.2 to 2.6/100,000 individuals in men, with papillary thyroid cancer being the most frequently diagnosed type. While most of these nodules are nonfunctioning and benign, some may be hyperfunctioning ("hot" nodules), potentially causing thyrotoxicosis. Differentiated thyroid cancers, such as papillary and follicular thyroid carcinoma, are typically considered "cold" on scintigraphy, rarely presenting with hyperthyroidism. This case series describes a unique presentation of papillary and follicular thyroid carcinoma in two patients with thyrotoxicosis secondary to a hyperfunctioning nodule ("hot" nodule). Both patients presented with signs of hyperthyroidism. Diagnostic imaging revealed a hyperfunctioning thyroid nodule and subsequent histopathology confirmed the presence of both papillary and follicular carcinoma. This case series highlights the rare coexistence of differentiated thyroid cancer and thyrotoxicosis due to a hot nodule. It emphasizes the importance of thorough evaluation of hyperfunctioning nodules to rule out malignancy. Early recognition and appropriate management are crucial in optimizing patient outcomes.