A case of primary pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma with an extensive infiltrative shadow in the middle and lower lobes of the right lung

In 2019, an abnormal shadow was noted in the chest of a 50-year-old woman during a health checkup at work, and she was referred to our department for detailed examination. Chest X-ray and computed tomography (CT) showed an extensive infiltrative shadow on the mediastinal side of the middle and lower lobes of the right lung. Bronchoscopy, brush cytology, and bronchoalveolar lavage cytology revealed no significant findings. Because of the suspicion of inflammatory shadow or tumor (e.g., malignant lymphoma, invasive mucinous adenocarcinoma), surgery was performed for diagnostic and treatment purposes. Right middle lobectomy was performed, and a rapid intraoperative pathological diagnosis of suspected pulmonary malignant lymphoma was made. Thus, right lower lobectomy and mediastinal lymph node dissection were also performed. Pathological and immunohistochemical examinations established the final diagnosis of pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma. At 2 years and 6 months of follow-up, the patient is alive without recurrence. Pulmonary MALT lymphoma is a rare disease and is often difficult to diagnose because of the lack of specific imaging findings. Therefore, most cases undergo lesion excision for pathological diagnosis. According to the literature, pulmonary MALT lymphoma often involves multiple lesions, and a solitary lymphoma has good prognosis after curative resection and is thus considered a good indication for surgical resection. Although no consensus has been reached regarding whether postoperative chemotherapy is necessary, there have been reports of successful treatment after the advent of rituximab, and the therapeutic options are expanding.