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Abstract A 79‐year‐old woman was referred to our facility because of an abnormal chest shadow. Chest computed tomography (CT) showed a solitary right middle lung nodule with a maximum diameter of 3 mm and anterior mediastinal nodule with a maximum diameter of 21 mm. The lung nodule was suspected of being a primary lung cancer rather than a metastatic tumor because there were no primary malignant tumors, apart from an anterior mediastinal tumor visible on diagnostic imaging, including F18 fluorodeoxyglucose‐positron emission tomography, and a solitary lung nodule. Partial lung resection by video‐assisted thoracoscopic surgery (VATS) was performed, and the intraoperative frozen section of the tumor tissue resulted in a diagnosis of carcinoid tumor. As a result, right middle lobectomy by VATS was performed. The final histological diagnosis of the permanent specimen was intrapulmonary type A thymoma. VATS thymectomy was performed three months later. The histological diagnosis was type A thymoma with intrapulmonary metastasis (Masaoka stage IVb). Additional therapy was not performed because complete resection was achieved. Follow‐up CT was performed once every six months after the operation. The patient has been followed up for one year without any further recurrence.

A 75‐year‐old woman underwent thoracoscopic right upper lobectomy for lung cancer. A histopathological examination showed adenocarcinoma, pT1aN0M0 stage IA1. At six months after surgery, chest computed tomography (CT) revealed pericardial nodules that had not been detected before pulmonary resection. Postoperative CT performed two months later revealed that the nodules were growing and F18 fluorodeoxyglucose‐positron emission tomography showed a maximum standardized uptake of 9.87. Blood tests revealed no elevated tumor markers, with the exception of a mildly elevated interleukin‐2. Based on the above results, thoracoscopic biopsy was performed due to the suspected recurrence of lung cancer or malignant lymphoma. The histopathological examination of the nodule revealed immunoglobulin G4 (IgG4)‐related inflammatory pseudotumor. The serum IgG4 levels were elevated (358 mg/dL, normal: 4.5–117.0 mg/dL). No additional treatment was required because all nodules were observed to have disappeared naturally on a follow‐up CT scan performed two months after the surgical biopsy. The patient has been followed‐up for two years without recurrence. Key points Significant findings of the study We report a case of pericardial immunoglobulin G4‐related inflammatory pseudotumor that appeared after right upper lobectomy for lung cancer, and which naturally disappeared without any treatment. What this study adds There was an immunoglobulin G4‐related inflammatory pseudotumor which appeared as multiple nodules in the pericardial space, and this should be kept in mind when considering the differential diagnosis of intrapericardial nodules.

Abstract Several authors have previously reported that patients with pulmonary combined large cell neuroendocrine cancer ( LCNEC) have a poor prognosis and there is no consensus on the treatment strategy for combined LCNEC as well as LCNEC. Here, we report the case of a long‐term survivor with pulmonary combined LCNEC. The patient was a 60‐year‐old man who underwent thoracoscopic right lower lobectomy. The final histopathology and staging of the tumor showed LCNEC combined with squamous cell carcinoma and T2aN0M0 stage IB. Multimodality treatments including chemotherapy, radiotherapy and surgery for several recurrences were performed after the pulmonary surgery. After immune checkpoint inhibitor (ICI) therapy with nivolumab, all the metastatic lesions shrunk and a partial response was maintained at five years after the first surgery. In our case, ICI after multimodality therapy combining cytotoxic anticancer drugs and radiotherapy was effective in LCNEC with metachronous multiple metastases. Key points Significant findings of the study Immune checkpoint inhibitor after multimodality therapy combining cytotoxic anticancer drugs and radiotherapy was effective in LCNEC with metachronous multiple metastases. The patient survived over five‐years after the first surgery. What this study adds Immune checkpoint inhibitor may be effective in some LCNEC patients.