PAPILLARY AND MEDULLAR THYROID COLLISION TUMOR: A CASE REPORT AND LITERATURE REVIEW

Abstract

Collision tumors in the thyroid are extremely rare, representing only 1% of thyroid malignancies, and they involve the coexistence of two histologically distinct neoplasms within the same organ. This report presents the case of a 62-year-old male with a synchronous papillary and medullary thyroid carcinoma. Clinical examination revealed an asymptomatic anterior cervical mass. Imaging studies and fine-needle aspiration cytology suggested malignancy, leading to a total thyroidectomy. Histopathological and immunohistochemical analyses confirmed the diagnosis of a collision tumor, with immunohistochemistry revealing positivity for calcitonin, CEA, and markers consistent with both tumor types. Treatment involved radical surgery, with considerations given to the medullary component's aggressiveness. Due to the rarity of these cases, specific management guidelines are limited, highlighting the need for individualized approaches. Long-term monitoring, including serum markers and imaging, is essential for early detection of recurrence. This case underscores the complexity of managing collision tumors and calls for further research to establish evidence-based protocols.