Occult sporadic medullary microcarcinoma with lymph node metastases.

A sporadic form of medullary occult microcarcinoma was cytologically diagnosed, by fine-needle aspiration biopsy (FNAB), on metastatic cervical lymph nodes. The cytologic specimens were partially smeared and partially zinc-formalin-fixed, so that a microinclusion clot for immunohistochemical studies would be possible. The reactivity to calcitonin of neoplastic cells obtained from metastatic cervical lymph nodes supported the search for a thyroid tumor, which only a careful echographic study revealed. Under sonographic guidance, FNAB on a 0.5-cm hypoechoid nodule was performed. The smears were diagnostic of medullary carcinoma. A total thyroidectomy with node dissection was made. Diagn. Cytopathol. 1999;21:203-206.