Endocrine Abstracts

JOINT2497

Introduction: Papillary thyroid carcinoma (PTC), derived from follicular cells, is a common entity in endocrine oncology. In contrast, medullary thyroid carcinoma (MTC) is a less frequent pathology. The simultaneous occurrence of these two cancers is rare. We report three patients presenting with both PTC and MTC during the management of thyroid neoplasia, followed at the nuclear medicine department of CHU Sahloul.

Case Reports: Case 1: A 68-year-old female with a history of pulmonary and cutaneous sarcoidosis presented with a cervical swelling. The cervical ultrasound revealed signs of malignancy, which were confirmed by fine-needle aspiration cytology (FNAC), prompting a total thyroidectomy (TT) with bilateral mediastino-recurrent lymph node dissection (MRLD). Histopathological examination identified a micro-PTC measuring 0.2 cm and an MTC measuring 1.5 cm in the left lobe, with no lymph node involvement. The patient received ablative radioactive iodine (RAI) therapy (30 mCi) and showed favorable biochemical and morphological outcomes for PTC. Case 2: A 44-year-old female discovered a 1 cm cervical swelling during self-palpation. Cervical ultrasound revealed a poorly defined hypoechogenic nodule with microcalcifications, classified as EU-TIRADS V. She underwent TT with bilateral MRLD. Histopathological analysis revealed a mixed medullary and papillary carcinoma of the right thyroid lobe, with no lymph node metastasis. The PTC was classified as pT1aN0Mx, and the MTC as T3N1b. She received ablative RAI therapy (100 mCi) with a good biochemical and morphological response for PTC. Case 3: A 69-year-old male with diabetes presented with a suspicious lateral cervical swelling. Cervical ultrasound showed a 28 mm thyroid nodule classified as EU-TIRADS V, along with markedly elevated calcitonin levels (>5000 ng/ml). Preoperative staging was negative for distant metastasis, and the patient underwent TT with bilateral MRLD. Histopathology revealed a low-grade MTC in the right lobe measuring 4.4 cm (classified as pT3bN1bM0) and a millimetric PTC (classified as pT1aN1aM0). The patient received ablative RAI therapy (30 mCi) with favorable biochemical and morphological outcomes. Postoperatively, calcitonin levels decreased to 47 ng/ml. A follow-up by cervical ultrasound and serum calcitonin was indicated.

Conclusion: The synchronous association of MTC and PTC is rare, with only a few cases reported in the literature. This observation highlights the importance of preoperative calcitonin testing in patients with thyroid nodules. The prognosis primarily depends on the MTC, as PTC typically has a favorable prognosis and slow progression.