Clinical data: a 32-year-old woman was referred for an evaluation of a nodule discovered by herself for 6 months.

Palpation: there were two palpable nodules in the left thyroid, the lower one was hard on palpation.

Functional state: euthyroidism with TSH 0.87 mIU/L.

Ultrasonography: there were two nodules in the left lobe. The upper one was echonormal while the lower hypoechogenic one contained microcalcification and a cotton-like larger hyperechogenic patch and presented an irregular shape and a type 3 vascular pattern.

Cytological diagnosis: suspicion of medullary carcinoma.

Blood test for calcitonin: serum-level of calcitonin was 13.7 pM/L  (normal value: 0-3.36).

Histopathology: medullary cancer.