In this case, radiological criteria might suggest the possibility of thyroid lymphoma such as the diffuse involvement of the thyroid gland, the marked diffusion restriction, and the avid FDG uptake, as well as the distribution of the enlarged cervical lymph nodes.

Thyroid lymphoma is rare, accounting for a minority of both thyroid malignancies and lymphoma in general. The thyroid may be affected primarily or secondary to lymphoma elsewhere.

Hashimoto thyroiditis is a major risk factor (~60 times increased risk) but the development of thyroid lymphoma is still rare in this group. 

Thyroid lymphoma may be a focal mass or diffuse gland enlargement.