A Rare Case of Thymic Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma

Thymic mucosa-associated lymphoid tissue (MALT) lymphoma is a type of diffuse B-cell lymphoma located in the thymus that is extremely rare. This case report illustrates the treatment of a 39-year-old Asian female patient with thymic MALT lymphoma. She presented with constitutional symptoms and chest pain. A CT scan of the chest revealed a soft tissue density in the right anterior mediastinum measuring 4×4.2 cm, likely originating from the thymus. After counseling between the options of surveillance imaging, CT-guided biopsy, or upfront surgery, the patient opted for surgical resection of the mass for both diagnostic and therapeutic intent. She then underwent robot-assisted excision of the mediastinal mass and total thymectomy on July 6, 2023. Intraoperative findings noted a 3 cm thymic mass without direct invasion into other local structures. The histological report revealed extranodal marginal zone lymphoma of MALT type. The patient was then referred to medical oncology, where it was determined that surgical resection of the tumor in her case was sufficient for oncological treatment, and no further radiotherapy or chemotherapy was required. The patient was also screened for possible autoimmune conditions and was found to be ANA positive, as thymic MALT lymphoma has known autoimmune associations with Sjögren's disease and SLE, among others.