title: [Metastatic cancers of the thyroid gland. Diagnostic difficulties].
abstract: Metastatic carcinoma of the thyroid is uncommon in surgical pathology and may masquerade as primary thyroid cancer. We studied 6 cases of biopsied and/or surgically resected metastatic carcinoma of the thyroid and their corresponding primary carcinoma, with emphasis on the differential diagnosis. There were 4 men and 2 women patients aged 44 to 77. The primary carcinoma was a breast infiltrating duct carcinoma (3 cases), a colorectal adenocarcinoma (2 cases) and a bronchial oat-cell carcinoma (1 case). The interval between primary carcinoma and secondary thyroid carcinoma was 2 to 9 years in 4 cases; 2 other cases showed simultaneous occurrence. Five patients died with widespread metastases 1 to 14 months following the diagnosis of secondary carcinoma of the thyroid; 1 patient was alive after 24 months. The histological differentiation of secondary from primary thyroid cancer may be difficult in the following situations: clear-cell, Hürthle-cell and signet ring cell changes; positivity of mucins stains; production of melanin; epidermoid differentiation; very rare miscellaneous tumours ("columnar cell carcinoma" and primary thymoma of the thyroid). Immunoperoxidase methods and mucin histochemistry may help.
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000556:secondary*; D000328:Adult; D000368:Aged; D001943:Breast Neoplasms; D002277:Carcinoma / Q000473:pathology / Q000556:secondary*; D018288:Carcinoma, Small Cell / Q000473:pathology / Q000556:secondary*; D003110:Colonic Neoplasms; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008175:Lung Neoplasms; D008297:Male; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000473:pathology / Q000556:secondary*
vernacular_title: Cancers métastatiques de la glande thyroïde. Difficultés diagnostiques.