[Calcitonin measurement in fine needle aspiration washout fluid : when biology arbitrates between two cytological diagnoses].

Abstract

Medullary thyroid carcinoma is a lesion whose preoperative diagnosis mainly relies on serum calcitonin measurement and cytology obtained by fine-needle aspiration. A marked elevation of calcitonin during the evaluation of a thyroid nodule constitutes a warning signal. The sensitivity of cytology is limited because of the tumor's morphological heterogeneity. Measurement of calcitonin in the washout fluid from the aspiration needle and syringe significantly improves diagnostic performance, both for thyroid nodules and for suspicious lymph nodes. This clinical vignette illustrates the importance of integrating biological and cytological data to optimize the initial management. It raises several questions: What is the role of serum calcitonin measurement in the evaluation of thyroid nodules? Why can cytology miss the diagnosis of medullary carcinoma? What benefits does measuring calcitonin in fine-needle aspiration washout fluid provide? Finally, how can the accuracy of the preoperative diagnosis influence the surgical strategy ?