Collision thyroid tumour.

Area of Science:

• Endocrinology
• Oncology
• Pathology

Background:

• Thyroid collision tumors are rare, comprising less than 1% of thyroid malignancies.
• They typically involve the coexistence of two distinct histological types, most commonly papillary thyroid carcinoma (PTC) and medullary thyroid carcinoma (MTC).

Purpose of the Study:

• To report a rare case of a thyroid collision tumor comprising both PTC and MTC.
• To discuss the diagnostic challenges, treatment modalities, and prognostic factors associated with this rare entity.

Main Methods:

• A case report of a male patient presenting with neck swelling.
• Diagnostic workup included imaging and fine-needle aspiration cytology.
• Surgical management involved total thyroidectomy, paratracheal dissection, and neck dissection, followed by histopathological examination.
• Postoperative management included radioiodine therapy, Ga-68 DOTANOC scan, and external beam radiotherapy.

Main Results:

• Histopathology confirmed a collision tumor of PTC and MTC, despite initial cytological suspicion of only PTC with metastasis.
• The patient underwent a comprehensive multimodal treatment approach.

Conclusions:

• Thyroid collision tumors are rare and complex, requiring thorough histopathological evaluation.
• Prognosis is influenced by the more aggressive component, typically MTC.
• Multimodal treatment and serial monitoring of tumor markers (calcitonin, thyroglobulin) and imaging are crucial for effective management and follow-up.