[Two Resected Cases of Primary Pulmonary Mucosa-Associated Lymphoid Tissue Lymphoma, Differently Diagnosed in Chest Tomography Scan].

Case 1: A 81-year-old man was admitted to our hospital because of a mass shadow on chest x-ray examination. Chest computed tomography (CT) showed a 1.5 cm nodule in the middle lobe of the right lung. We suspected a primary lung cancer and performed video-assisted right middle lobectomy. Histopathological examination showed a white, elastic, hard and solid 30 × 10 × 10 mm nodule with infiltration of small-to-medium-sized lymphocytes that were positive for CD20 and CD79a, and negative for CD10 and Cyclin D1 in immunohistochemical staining. We diagnosed mucosa-associated lymphoid tissue (MALT) lymphoma. Case 2: A 67-year-old woman was admitted to our hospital because of a mass shadow in the right upper lobe on chest x-ray and chest CT. As the lesion had not grow in 1 year, the patient strongly wanted it resected, therefore we performed wedge resetion of the right upper lobe via video-assisted thoracic surgery. Histopathological examination showed a white, elastic, hard and solid 25 × 25 × 16 mm nodule with infiltration of small-to-medium-sized lymphocytes that had positive staining of CD20 and CD79a, and negative staining of CD10 and Cyclin D1. We diagnosed MALT lymphoma. Primary lung MALT lymphoma shows a variety of shadows on chest CT, similar to lung cancer and other inflammatory diseases. Local therapies such as surgery and radiation therapy are effective against early stage MALT lymphoma, but there is no consensus of a standard surgery.