Cystic metastases from papillary adenocarcinoma of the thyroid with comments concerning carcinoma associated with thyroglossal remnants

Papillary adenocarcinoma of the thyroid not uncommonly presents as a soft or cystic mass in the neck as a result of cervical lymph node metastases. In adults this may be one of the more common cervical cystic lesions and should be considered in the differential diagnosis of any cystic mass in the neck even if the thyroid is normal by palpation. The primary tumor in the thyroid is often very small in relation to the size of the metastases. Recognition that not all cysts in the neck are benign can lead to earlier diagnosis and treatment. This carcinoma usually carries a good prognosis and is amenable to therapy. Whether papillary adenocarcinomas reported to be associated with thyroglossal duct remnants should be considered as originating in thyroid rests or as metastases from the thyroid gland should remain an open question in individual cases until a primary malignancy of the thyroid has been demonstrated not to be present. Also, some of these may be cystic papillary adenocarcinomas of thyroid origin only and not thyroglossal cysts at all.