[Thyroid nodules].

To be able to identify those thyroid nodules at an elevated risk of developing cancer from among the numerous nodules detected (demonstrable by sonography in 20% of the population) an effective rational approach to the differential diagnosis is required. In the meantime, relevant guidelines are available. Sonography and determination of TSH form the basis of every diagnostic approach to thyroid nodules. Single sonographic signs of malignancy are too insensitive and unspecific for differentiating between benign and malignant nodules. However, together with the patient's history, the combination of several sonographic criteria may be of help in identifying cases for fine-needle aspiration cytology (FNAC). Every normally functional or hypofunctional (cold) nodule > or = 1 cm should be subjected to FNAC: In the case of multinodular glands, cold areas should be selected for FNAC by scintigraphy, even in euthyrotic patients.