Concomitant papillary thyroid carcinoma and mucosa-associated lymphoid tissue thyroid lymphoma in the setting of Hashimoto thyroiditis

The simultaneous occurrence of papillary thyroid carcinoma (PTC) and mucosa-associated lymphoid tissue (MALT) lymphoma of the thyroid gland is extremely rare, and many questions about their diagnosis and treatment remain unsolved. We report three cases of patients with both PTC and MALT thyroid lymphoma in the setting of Hashimoto thyroiditis (HT). Patient characteristics, pre-operative examination, histological findings, treatments, and follow-up were reviewed. In addition, we searched PubMed, Embase, and ISI Web of Science databases for articles published in the English language using the key words "lymphoma" and "thyroid", and we reviewed almost all the reports about simultaneous occurrence of PTC and MALT thyroid lymphoma. In conclusion, PTC and MALT thyroid lymphoma can exist concomitantly, especially in patients with longstanding HT. These rare cases highlight the importance of close communication between clinicians, histopathologists, and radiologists to ensure that such rare cases are not missed; a multidisciplinary approach and careful surveillance are also needed.