A Case of Mesothelial-Cell Inclusions in the Mediastinal Lymph Nodes After Lung Cancer Surgery

Mesothelial-cell inclusion (MCI) is an inclusion of mesothelial cells found in lymph nodes. Although it is a rare condition, differentiating it from lymph node metastasis is essential to avoid a misdiagnosis. We reported, for the first time, a case of MCI after lung cancer surgery. The patient was a 76-year-old Japanese man with a history of bilateral radical surgery for lung cancer. Follow-up computed tomography performed at 7 years after the initial surgery revealed an enlarged right cardiophrenic angle lymph node. It was resected through video-assisted thoracic surgery, and histopathology revealed non-dysplastic ductal proliferation. Immunohistochemistry was positive for AE1/3, D2-40, calretinin, and WT-1, and negative for CD31, CD34, and factor VIII. Based on these findings, MCI was finally diagnosed. Although the presence of metastasis is the first possible cause for the enlarged lymph nodes in such cases, MCI must also be considered.