[Thyroid metastases: the echographic and computed tomographic aspects]

The modern integrated approach to neoplastic diseases permits to detect metastatic lesions in uncommon sites, such as the thyroid gland. We reviewed the ultrasonographic (US) and Computed Tomographic (CT) patterns of secondary thyroid lesions, comparing imaging findings with primary tumor histopathologic diagnosis.

We reviewed a series of 10 thyroid metastases diagnosed from 1986 to 1995 at staging (4 cases) or follow-up (6 cases) examinations; in the latter, metastases were diagnosed 39 to 89 months (mean: 58 months) after the primary tumor. The patients were 7 women and 3 men, 55 to 94 years old (mean: 65 years). The final diagnosis was made at cytology (4 cases), histology (5 cases) or surgery (1 case).

The primary tumors were breast cancer (2 cases), melanoma (2 cases), small cell lung cancer, bronchioalveolar carcinoma, mucoid stomach adenocarcinoma, renal carcinoma, colon carcinoma and leiomyosarcoma (1 case each). The thyroid lesion was unifocal in 6 patients and multifocal in 2; the gland was diffusely involved in 2 patients. Dysphagia was found in all patients. Thyroid function was normal in 6/7 patients and one had hyperthyroidism; normofunctional goiter was found in another patients. US showed focal or diffusely infiltrating hypoechoic lesions; likewise, inhomogeneously hypodense areas with mild contrast enhancement were observed at CT. Thyroid secondary lesions exhibited variable patterns when necrotic, hemorrhagic or calcific areas were included; correlations with primary tumor-pathogenetic and histologic features were often observed. Survival rate was 2-60 months (mean: 19 months).

Since imaging findings in thyroid metastases are often not specific and sometimes atypical, fine needle biopsy of suspicious lesions should be carried out for both staging and follow-up.