Clinical data: a 71-year-old woman was referred for an evaluation of a rapidly increasing neck tumor which evolved over five weeks. The patient had severe dyspnea and dysphagia for 5 days.

Palpation: a large, stone-hard tumor in both lobes of the thyroid.

Functional state: euthyroidism (TSH 3.93 mIU/L, FT4 10,1 pM/L).

Ultrasonography: both lobes were extremely enlarged with a maximal diameter greater than 13 cm. Both lobes spread substernal and retrotracheal. The thyroid was composed of multiple hypoechogenic nodules with only a small intact part. The nodules contained hyperechogenic areas corresponding to necrosis.

Cytological diagnosis: malignant tumor. Anaplastic or medullary carcinoma.

Serum calcitonin resulted in normal value.

Final preoperative diagnosis: anaplastic carcinoma.

Histopathology: anaplastic cancer.

Comments:

1. The cytological pattern, i.e. the high cellularity, the presence of well-preserved polygonal cells and the lack of follicle or papillary formation might correspond even to medullary cancer. A few highly atypical, pleomorphic forms were the only cytological signs favoring anaplastic cancer.

2. The clinical presentation was almost pathognomic. We did not meet in our practice a medullary carcinoma with such an aggressive clinical behavior. Nevertheless, calcitonin determination is absolutely not superfluos facing with this cytological pattern.