C cells in normal thyroid aspirates.

OBJECTIVE: To quantify C cells in normal thyroid aspirates. STUDY DESIGN: Smears of 18 glands from patients with no thyroid disease, 8 women and 10 men aged on average 52.8 years, were analyzed. Five samples were aspirated from the upper, middle and lower thirds of each lateral lobe and from the isthmus. Smears were stained with anticalcitonin monoclonal antibody. RESULTS: C cells were detected in all specimens, ranging in number from 3 to 19 per gland, with 53.4% of the cells in the right lobe, 42.8% in the left lobe and 3.7% in the isthmus. The aspirates from the right lobe had 0-13 cells in the upper third, 0-9 in the middle third and 0-3 in the lower third. In the left lobe aspirates there were 0-7 cells in the upper third, 0-6 in the middle third and 0-2 in the lower third. One to two C cells were observed in the isthmus in only four cases. CONCLUSION: It is possible to determine the presence of C cells in normal thyroids and confirm studies conducted on histologic material; the cells were more frequently detected in the middle and upper third and mainly on the right side. They were rare in the isthmus. The search for C cells in thyroid aspirates is of great importance because it permits one to confirm rapidly, precisely and minimally invasively cases suspected of C cell hyperplasia, a preneoplastic condition that precedes the development of medullary carcinoma. In addition, the method shows numerical changes in these cells in such conditions as Hashimoto's thyroiditis and colloid goiter, in which the present results could serve as a control.