Concomitant presentation of Hashimoto's thyroiditis and maltoma of the thyroid in a twenty-year-old man with a rapidly growing mass in the neck.

We report an uncommon case of a 20-year-old man, who noted a painless, growing mass in his neck, which appeared in a weekend, associated with moderate dysphagia and weakness. Laboratory examination revealed an elevated serum thyrotropin of 25 mU/L, normal serum triiodothyronine and thyroxine levels, and high titers of antithyroglobulin and antithyroid peroxidase antibodies. The neck lesion showed a depressed iodine uptake in the left thyroid lobe, which had an asymmetrical pseudocystic pattern associated with poor vascularization in the ultrasound scan. Cytologic examination showed a lymphocyte thyroiditis in association with lymphoma of large cell arising from mucosa-associated lymphoid tissue (MALT-lymphoma or maltoma). The patient underwent a left thyroid lobectomy while being treated with levothyroxine for Hashimoto's thyroiditis, and the surgical treatment was further complemented with chemotherapy using fludarabine. The histologic examination confirmed the cytologic findings and the immunohistochemistry showed a B-cell type maltoma. Additional investigation provided no evidence of disease in other tissues. The clinical course has been favorable in the first 2 years of follow-up, with no evidence of local or systemic recurrence of the disease.