Objective  To analyze the clinicopathological characteristics of secondary neoplasms of the thyroid gland (SNTGs).

  Methods  SNTG Patients who had pathology diagnosis of SNTGs between January 2010 and December 2019 at West China Hospital, Sichuan University were retrospectively enrolled. The SNTG cases were divided into two groups, a local invasion group and a distant metastasis group, and their clinical features were reviewed.

  Results  The study involved 88 patients, with a female-to-male (F/M) ratio of 1/3 and an average age of 56 years. The local invasion group consisted of 72 patients (F/M, 1/8) who had the following types of tumors: 65 had squamous cell carcinomas (45 originated from larynx and 10 from laryngopharynx), 4 had adenoid cystic carcinomas, 1 had neuroendocrine carcinoma of esophagus, 1 had giant cell tumor, and 1 had type B3 thymoma. The distant metastasis group consisted of 16 patients (F/M, 7/1), all with previously confirmed history of malignancies of sites distant from the thyroid. Their primary tumor types were as follows, 6 had breast carcinomas, 5 had lung adenocarcinomas, 2 had nasopharyngeal non-keratinizing carcinomas, 1 had clear cell renal carcinoma, 1 had colon adenocarcinoma, and 1 had cervical squamous cell carcinoma.

  Conclusions  Given that SNTGs are generally rare, the local invasion cases were predominantly squamous cell carcinomas that mainly originated from the larynx and the patients usually had no previous history of malignancy, while the distant metastasis cases often had a corresponding history of malignancies, consisting mainly of breast carcinoma and lung carcinoma.