[A case of primary malignant lymphoma of thyroid in young man].

The aim of this study is to present a case of a 36-year old male with a rare thyroid malignancy--a primary thyroid lymphoma. The patient was admitted to the Department of Endocrinology due to a rapidly enlarging left-sided tumor of the neck and hoarseness lasting for 2 weeks. The only abnormality found on biochemical testing was a slightly elevated titre of anti-TPO antibodies. On X-ray examination, both a compression and deviation of the trachea was found. Ultrasound examination of the neck revealed a left-sided thyroid lesion and fine needle aspiration (FNA) was performed under ultrasound guidance. A monotonous population of mid-size lymphoid cells was found with negative immunocytochemistry for thyroglobuline and CD 68. After hematological and pathological evaluation the FNA report was considered as non-diagnostic. Taking into consideration the presence of rapidly occurring compressive symptoms caused by a tumor of unknown cytological origin, the patient was referred to urgent thyroid surgery. Pathological report of postoperative specimen allowed for the final diagnosis of a malignant lymphoma originating from non-Hodgkin B cells of the thyroid gland; diffuse large B-cell lymphoma (DLCL) according to WHO classification. L-thyroxin substitution therapy, chemo- and radiotherapy were used after the operation. The described case of a very rare type of primary thyroid malignancy illustrates difficulties which can be encountered in diagnostic approach and therapeutic decision making in patients with rapidly enlarging thyroid tumors.