Clinical presentation: A 59-year-old woman was referred for an evaluation of rapidly increasing mass in the right side of the neck causing dysphagia and palsy of the recurrent nerve. The lesion developed within 3 months.

Palpation: a hard, almost fixed tumor in the right lobe. The size of the lesion exceeded 15 cm.

Functional state: euthyroidism (TSH-level 3.08 mIU/L).

Ultrasonography. There was a huge hypoechogenic mass in the region of the thyroid and in the right side of the neck. Only a small part of the right thyroid lobe was intact. The left thyroid was echonormal. The lesion was avascular.

Cytology: suspicion of non Hodgkin lymphoma.

Biopsy was performed from the lesion and histopathology revealed large B cell lymphoma.

Comments.

1. The cytological picture was identical with a small cell malignant tumor. Differential diagnostics included a metastatic small cell lung tumor and malignant lymphoma. The clinical presentation substantially decreased the likelihood of the former.

2. The fact that the left thyroid was intact strongly argued against the possibility of a MALT-type lymphoma which arises in Hashimoto's thyroiditis.