Clinical data: a 48-year-old woman who had been treated for Graves-Basedow's disease attended a follow-up examination. The patient had been examined 2 months earlier, when US was performed and revealed  a nearly normal echo pattern without any discrete echo abnormality (the first US picture).  She was then well. 2 weeks before the present examination she felt dyspnea, which progressed over the next 2 weeks.

Palpation: a moderately enlarged thyroid and an enlarged, hard cervical lymph node on the right were palpable.

Functional state: euthyroidism.

Ultrasonography: besides the enlarged cervical lymph node, US revealed a hypoechogenic inhomogeneous nodule in the right lobe of the thyroid (the second US picture).

Cytology was performed. The FNAC result on both lesions (palpation-guided on the lymph node, and US-guided on the thyroid) was malignancy, i.e. a suspicion of small cell lung cancer, which was confirmed by immunocytochemistry; the tumor cells did not express LCA, but gave a positive reaction for neuron-specific enolase.

The patient was referred for a pulmonary evaluation. Bronchoscopy revealed a tumor in the lower lobe of the right lung.

Bronchoscopic brush cytology: gave the diagnosis of small cell lung cancer.

Comment: the possibility of a medullary carcinoma had to be considered on FNAC of the thyroid.