Lymphoid infiltration can be seen in some lesions such as Hashimoto's thyroiditis, subacute thyroiditis and several neoplasm of the thyroid. In case of malignancy, there are a few reports of lymphoid infiltration in the diffuse sclerosing variant of papillary carcinoma. But heavy lymphoid infiltraton without evidence of sclerosis is uncommon.
We experienced a case of papillary oxyphilic carcinoma with massive lymphoid infiltration, which looks like Warthin tumor of salivary gland. However cytological feature of epithelial cells exhibit that of papillary carcinoma.