[Cytologic diagnosis of medullary carcinoma of the thyroid gland]

Over a five year period 50 malignant tumours (3.8% of investigations) has been histologically proved in a group of 1378 patients who underwent fine needle aspiration biopsy of thyroid. Five of these were medullary carcinomas (0.38% of investigation, 10% of malignancies). During revision and cytohistological correlation the most important cytologic diagnostic features for the sequential diagnosis of medullary carcinoma especially in cases without indicative clinical symptomatology have been checked. The following proved to be indicative especially if coinciding: a) background formed by blood with minimum or no colloid; b) clusters of epithelial cells with poor cohesion, sometimes multilayered, microfollicular, or stroma-like fusiform cells; c) striking anisocytosis, polygonal, plasmacytoid, fusiform, polyploid, and binucleated cells and naked nuclei in the background; d) striking anisokaryosis, at least part of the nuclei ovoid or elongated, chromatin rough, giant nuclei; e) amyloid identifiable in some tissue micro-fragments. If additional smears or cyto-block material are available it may be possible to establish the diagnosis at the cytology level using amyloid staining, argyrophilia test or immunohistochemistry. However if there is any cytological suspicion of medullary carcinoma, serum calcitonin should be investigated to confirm the preoperative diagnosis of medullary carcinoma enabling the patient to undergo one-step radical surgery.