Ultrasonographic and clinical pathological features of intrathyroid thymic carcinoma

Abstract

Objective To investigate the ultrasonographic and clinical pathological features of intrathyroid thymic carcinoma(ITTC). Methods The ultrasonographic and clinical pathological features of 11 cases of pathologically confirmed intrathyroid thymic carcinoma were analyzed retrospectively. The size, shape, boundary, internal echo, calcification, cystic change, blood flow of the lesion and lymph nodes of the neck were recorded. TI-RADS classification was performed on the lesion, and the medical history, clinical symptoms and treatment process of the patients were recorded. Results The lesions of all 11 patients were solid and located in the lower pole or middle-lower part of the thyroid, 8 cases were located in the right lobe of the thyroid gland (8/11, 72.7%), and 3 cases were located in the left lobe (3/8, 27.3%). The maximum diameter diameter of the lesions was (3.55±0.51)cm. All the lesions were hypoechogenicity or marked hypoechogenicity and ill-defined margin. The internal echo of the lesions were heterogeneous. Ten lesions were characterized by striped hyperechogenicity interiorly on ultrasonograms. According to TI-RADS classification, 2 cases were class 4a, 3 cases were class 4b, 2 cases were class 4c and 4 cases were class 5. There was no cystic component or calcifcation in all lesions, and there was no taller-than-wide shape. Three of 11 cases were accompanied by Hashimoto′s thyroiditis. Postoperative pathology showed that 5 cases had cervical lymph node metastasis, 5 had perithyroidal soft tissue in ltration, of them, 3 cases had recurrent laryngeal nerve, 2 cases invaded the esophageal wall, and 3 cases invaded the striated muscle of the neck. Immunohistochemistry showed that CD5 and CD117 of all lesions were positive. All patients underwent surgery, and 3 of them underwent radiotherapy and chemotherapy after surgery. Conclusions There are common sonographic features of intrathyroid thymic carcinoma, which are located at the lower pole or middle-lower of the thyroid gland, presenting a solid hypoechogenicity or marked hypoechogenicity, with ill-defined margin and striped hyperechogenicity interiorly on ultrasonograms. These sonographic features are helpful for the diagnosis of ITTC. Key words: Ultrasonography; Intrathyroid thymic carcinoma; Pathology