An unsuspicious thyroid nodule with fatal outcome.

INTRODUCTION: Over the last few years, several scientific societies have introduced specific evaluation systems to stratify the risk of malignancy of thyroid nodules. Most of these classifications have been created on the basis of ultrasonographic features of the commonest thyroid carcinoma histotype. Herein, we report a case of anaplastic thyroid carcinoma presenting at ultrasound (US) examination as an unsuspicious thyroid nodule associated with distant metastases, which was followed by the patient's death a short time later. CASE REPORT: A 77-year-old woman, because of worsening weight loss and vague abdominal pain, underwent a whole-body computed tomography scan, which revealed a large mass adherent to the large bowel, multiple pulmonary nodules, and a solitary thyroid nodule of the left lobe. On US, a round, well-defined, mixed solid-cystic, isoechoic lesion with a maximum diameter of 45 mm and peripheral vascularity was confirmed. No microcalcifications, extrathyroidal extension, cervical lateral lymphadenopathy, tracheal deviation, or compression were found. The nodule was classified as low or very low risk according to six US malignancy risk classification systems. Although only two of these recommended fine-needle aspiration cytology, on the basis of a dimensional criterion, the procedure was performed, the cytology report suggesting anaplastic cancer. Following total thyroidectomy, the histological examination revealed the presence of a follicular thyroid carcinoma with diffuse areas of anaplastic dedifferentiation.
CONCLUSION: This case highlights the importance of defining the US characteristics of rare variants of thyroid neoplasms, since an early diagnosis is decisive in defining the patient's prognosis.