Thyroid lymphoma is an uncommon disease. We report a case of diffuse large B-cell lymphoma presenting as a rapidly expanding neck mass.

Case:

An 81 year old man presented with a few months history of cervical and supraclavicular lymphadenopathy, and a diffuse firm thyroid enlargement. He did not have any B-symptoms (fever, weight loss, night sweats), stridor or dysphagia. However, he had recent onset of voice hoarseness. He was found to be profoundly hypothyroid (TSH 45mIU/L, free T4 8.2pmol/L) with normal anti-thyroid antibody levels.

CT scan revealed an extensively enlarged thyroid with retrosternal extension, lateral displacement of neck vessels and minor compression of trachea, as well as extensive lymphadenopathy in the jugular chain, prevertebral and supraclavicular regions. On ultrasound, the thyroid had a diffuse heterogeneous hypoechoic echotexture and increased vascularity, with no normal thyroid tissue visualised. Both the initial thyroid fine needle aspiration biopsy and the subsequent core biopsy were non-diagnostic. Excisional biopsy showed diffuse atypical lymphoid cells with a few probable atrophic thyroid follicles. Diffuse large B-cell thyroid lymphoma was confirmed only on immunohistochemistry.

He had dual modality treatment (chemotherapy followed by adjuvant radiotherapy to the thyroid region) which resulted in significant reduction in the thyroid mass and lymphadenopathy. He currently remains in remission two years after treatment.

Discussion:

Although rare, thyroid lymphoma should be considered in a patient with rapidly enlarging goitre. This case demonstrates the difficulties in obtaining the diagnosis of primary thyroid lymphoma using fine needle aspiration cytology, where the use of excisional biopsy is often required for diagnosis. It also highlights the importance of definitive diagnosis, as effective treatment is available and good outcome can be achieved in many cases.