Usefulness of calcitonin (CT) measurement in wash-out fluid from fine needle aspiration biopsy in thyroid nodules of patients with dectectable serum CT
Giulia Renzini, Teresa Rago, Paolo Passannanti, David Viola, Barbara Cosci, Eleonora Molinaro, Lucia Grasso, Fabiana Lucchetti, Paolo Vitti, Aldo Pinchera & Rossella Elisei
Up to now there isnt any study to validate the CT measurement in wash-out-fluid from FNAB in the diagnosis of medullary thyroid cancer (MTC). To demonstrate the usefulness of CT measurement in wash-out fluid from FNAB in thyroid nodules, we have retrospectively analyzed 25 cases with detectable serum CT in which CT measurement in wash-out-fluid from FNAB, citology and histological examination were available. In 7 cases CT level was <10 pg/ml: cytology was negative in 4 cases and not diagnostic in 3 cases. In 6 cases C cell iperplasia (ICC) or MTC was identified at histology but in a different nodule and in one case a focus of MTC was found in the punctured nodule. In 6 cases the CT level was 10<CT<1000 pg/ml: an MTC was found in 5 cases at histology; in one case a papillary thyroid carcinoma (PTC) was found both at histology and citology. Citology described a MTC in 2 cases and was not diagnostic in 3 cases. In 6 cases CT level was 1000<CT<10000 pg/ml. In all cases the histology described a MTC with the exception of one case in which there was a PTC. Citology found 4 cases of MTC, but it was not diagnostic in 2 cases. In 6 cases CT levels was >10000 pg/ml: in all cases a MTC was described both at histology and citology.
In conclusion CT level <10 pg/ml in wash-out-fluid from FNAB was indicative of absence of cancer in 86% of cases. The citology identifies only 57% of benign nodules. CT level >10 pg/ml in FNAB was indicative of presence of malignant or premalignant in 100% of cases (15 MTC; 1 ICC; 2 PTC), while cytology only in 72% of cases. We conclude that CT measurement in wash-out-fluid from FNAB increases diagnostic sensibility of citology from 65% to 95% and it represents an useful diagnostic tool to associate with citology when an MTC is suspected.