A case of intrathyroid thymic carcinoma

• Published in: jibi to rinsho Vol. 69; no. 3; pp. 214 - 220
• Main Authors: KURATOMI, Yuichiro, NODA, Mitsuki, SHIMAZAKI, Eriko, YAMAUCHI, Moriyasu
• Format: Journal Article
• Language: Japanese
• Published: JIBI TO RINSHO KAI 20.05.2023; 耳鼻と臨床会
• Subjects: CD5; 甲状腺内胸腺癌; 甲状腺癌; 胸腺様分化を示す癌
• ISSN: 0447-7227; 2185-1034
• DOI: 10.11334/jibi.69.3_214

A 56-year-old man presented with hoarseness, and laryngeal endoscopy revealed left vocal cord paralysis. Ultrasonography and contrast-enhanced CT revealed a tumor with an unclear boundary at the lower pole of the left thyroid lobe. Fine needle aspiration cytology showed malignant cells with strong nuclear atypia without the characteristics of papillary carcinoma. Thyroid cancer or other malignant tumors were suspected, and we performed resection of the left thyroid lobe, the tumor-infiltrated recurrent nerve, sternothyroid muscle, parathyroid gland, and surrounding adipose tissue. Immunohistochemical staining was positive for CD5, and negative for thyroglobulin and TTF-1 negative, leading to a diagnosis of intrathyroid thymic carcinoma: ITTC. Since the resection stump was negative and there was no distant metastasis, the patient was followed. Although ITTC has a strong tendency to infiltrate, the course is slower and the prognosis is better in comparison to anaplastic thyroid carcinoma and thyroid squamous cell carcinoma, and radical resection is the first choice of treatment. If a tumor with an unclear boundary is found at the lower thyroid pole and malignant cells different from papillary carcinoma cells are found on cytology, it is important to differentiate this disease and to perform radical resection with a negative margin.