Co-occurrence of papillary thyroid carcinoma and mucosa-associated lymphoid tissue lymphoma in a patient with long-standing hashimoto thyroiditis.

Papillary thyroid carcinoma (PTC) is a common affliction of the thyroid gland, accounting for 70% to 80% of all thyroid cancers, whereas mucosa-associated lymphoid tissue (MALT) lymphoma of the thyroid gland is uncommon. The simultaneous occurrence of both malignancies is extremely rare. We report the case of a patient with both PTC and MALT lymphoma in the setting of Hashimoto thyroiditis. An 81-year-old female patient was first admitted with goiter and hoarseness, which was attributed to an ultrasonographic thyroid nodule. Subsequent fine-needle aspirate, interpreted as suspicious of papillary thyroid cancer, prompted total thyroidectomy. MALT lymphoma was an incidental postsurgical finding, coexisting with PTC in the setting of Hashimoto thyroiditis. Although the development of MALT lymphoma is very rare, patients with longstanding Hashimoto thyroiditis should undergo careful surveillance for both malignancies.