肺原発MALTリンパ腫切除例の臨床病理学的特徴

Clinicopathological Features and Imaging Characteristics of Pulmonary Mucosa-associated Lymphoid Tissue Lymphoma

Mucosa-associated lymphoid tissue（MALT）リンパ腫は粘膜関連リンパ組織に発生する低悪性度のB細胞リンパ腫であり1），肺原発MALTリンパ腫は肺原発悪性腫瘍全体の0.5％以下とまれな疾患である2）．肺原発MALTリンパ腫は多彩な画像所見を示すことが知られており，術前画像診断のみでは肺癌などの他疾患との鑑別に苦慮することがある．われわれは，肺原発MALTリンパ腫の7切除例を経験したので，臨床病理学的および画像的特徴について報告する．

Background：Pulmonary mucosa-associated lymphoid tissue （MALT） lymphoma is a rare disease. We report seven cases of pulmonary MALT lymphoma.

Cases：Chest computed tomography （CT） revealed various morphological features, including a solitary mass, a solid nodule, and ground-glass opacity. Multiple nodules were observed in one patient. However, the tumor margins were ill-defined in all seven cases, and air bronchograms were identified in five cases. The solitary mass was found to extend along the pulmonary lymphatic vessels. Six patients underwent R0 resection, while one underwent an open lung biopsy. Histopathological findings in all seven cases showed lymphoepithelial lesions. Regarding their immunohistological findings, all patients were diagnosed with pulmonary MALT lymphoma. Two patients received postoperative chemotherapy with rituximab. The progression-free survival time was 52 （range, 22-122） months. Postoperative course was uneventful in all patients.

Conclusion：MALT lymphoma is characterized by an ill-defined margin, air bronchogram, and tumor extension along the pulmonary lymphatic vessels, all of which aid in diagnosis. MALT lymphoma is a low-grade lymphoma, and the prognosis is favorable. Therefore, follow-up examination without treatment can be one of the therapeutic options if patients are diagnosed with pulmonary MALT lymphoma.