Microcarcinomas measure less than 1.5cm in diameter and are clinically occult. They are usually found unexpectedly in surgical thyroidectomy specimens: (for example, in patients with Graves' disease, colloid goitre, or Hashimoto's goitre, or in follicular adenomas). In these circumstances, follow-up has shown no evidence of either recurrence of the carcinoma or the development of metastases. Cervical lymph node metastases of papillary carcinomas are usually associated with a palpable primary tumour. Occasionally, however, an excision biopsy of a solitary enlarged cervical lymph node is found to contain a deposit of a papillary carcinoma, and the primary is subsequently demonstrated as an occult microcarcinoma of the ipsilateral lobe on thyroidectomy.
