Clinical presentation: A 63-year-old man was referred for evaluation of a thyroid nodule which was discovered on follow-up examination of a malignant melanoma. The tumor was located in the forearm. Interferon therapy has been administered for 3 years. Hypothyroidism has developed six months after initiating the therapy.

Palpation: a not firm nodule in the left lobe.

Functional state: euthyroidism on daily 62.5 microgram levothyroxine (TSH 2.96 mIU/L).

Ultrasonography. The thyroid was echonormal and contained moderately hypoechogenic areas. The echogenicity index was around 30%. There was a hypoechogenic nodule in the ventral part of the left lobe. The nodule presented microcalcifications and blurred borders in the lower part. The vascularization was not specific.

Cytology resulted in papillary carcinoma.

A total thyroidectomy was performed. Histopathology disclosed a papillary carcinoma and Hashimoto's thyroiditis in the extranodular part.