[Papillary adenocarcinoma on ectopic thyroid tissue].

Objectives: To report a case of papillary adenocarcinoma occurring on ectopic thyroid tissue in the hyoid bone region.

Material And Methods: A 57-year-old patient consulted for a cervical mass appearing 1 year before, with no signs of compression. The thyroid function was normal.

Results: The examination showed a firm tumefaction, fixed on the hyoid bone, with undetermined limits, measuring approximately 8 cm. The thyroid gland was in the normal pretracheal position. The cervical tomodensitometry objectified an osteolytic process centered on the hyoid bone with a fleshy zone of tissue density and calcifications. Cervical MRI provided a more precise assessment of the extension of the mass and confirmed the integrity of the other structures, in particular the endo-larynx. The tumor was totally resected via a cervical approach. The pathologic study suggested a papillary adenocarcinoma on ectopic thyroid tissue. The treatment was completed by a total thyroidectomy with normal histological results.

Conclusions: Papillary adenocarcinoma on ectopic thyroid is a very rare situation. Its diagnosis is histological. Its treatment is primarily surgical, sometimes associated with radioiodine I-131 therapy.