The pathological diagnosis of mesothelioma is difficult because some neoplasms and benign mesothelial proliferation show similar pathological findings to mesothelioma. Lung carcinomas can be pathologically diagnosed with small biopsies, but the small samples obtained on a biopsy are sometimes not enough for a definitive diagnosis of mesothelioma. Thoracoscopy with general anesthesia is now the preferred method of obtaining sufficient material to make a pathological diagnosis of early-stage mesothelioma. Malignant mesothelioma is classified into epithelioid, sarcomatoid, and biphasic mesothelioma. It is important to use panels of positive and negative antibodies for the diagnosis of epithelioid and biphasic mesothelioma. However, mesothelial markers are often negative or only focally positive in sarcomatoid mesothelioma. Cytokeratin should be used for the diagnosis of sarcomatoid mesothelioma, and true sarcomas and sarcomatoid carcinomas should be ruled out. The separation of benign from malignant mesothelial proliferations is a major problem in the pathology of early-stage mesothelioma. BAP1 immunohistochemistry and p16 FISH help differentiate malignant tumors from benign mesothelial proliferations. Patients with early-stage pleural mesothelioma often have pleural effusion. Mesothelioma can be diagnosed based on the examination of the effusion using cell blocks with immunohistochemical and FISH analyses. Pathologists should take the clinical, radiologic, and pathologic features into consideration when making a diagnosis.

Objective. The aim of this study was to investigate the outcomes of induction chemoradiotherapy followed by surgery in patients with stage IIIA/N2 non-small-cell lung cancer (NSCLC). Methods. We retrospectively analyzed 48 consecutive patients with stage IIIA/N2 NSCLC who underwent induction chemoradiotherapy followed by surgery at Kurashiki Central Hospital between January 2005 and December 2013. Results. The median age was 69 (range, 49-79) years. Thirty-eight patients were male. The diagnoses included adenocarcinoma (n=22), squamous cell carcinoma (n=17), and other types (n=9). The regimens consisted of carboplatin and paclitaxel (n=43), and other regimens (n=5) plus concurrent radiation at a dose of 30 Gy (n=20), 40 Gy (n=21), or 50 Gy (n=7). A major response was obtained in 40 patients. Grade 3/4 toxicities were reported as a result of induction chemoradiotherapy in 29 patients. The 5-year relapse-free survival and overall survival rates were 54.3% and 59.0%, respectively. Multivariate analyses revealed that the administration of carboplatin and paclitaxel in induction chemoradiotherapy was an independent prognostic factor. Conclusion. Carboplatin and paclitaxel might therefore be a promising induction chemoradiotherapy regimen for stage IIIA/N2 NSCLC.

Background. The prognosis of resected N2 diseases (ipsilateral mediastinum node metastasis) in non-small cell carcinoma of the lung is heterogeneous and difficult to predict. To precisely assess the prognosis of N2 diseases, we made a lymphatic map of each pulmonary lobe and subdivided the current N2 diseases. Methods. We mapped the lymphatic pathways of each pulmonary lobe and classified these lymphatic pathways as follows: level 1: from the lung to the intra-pulmonary or hilar nodes (N1); level 2: from N1 to the ipsilateral mediastinum nodes (N2); and level 3: among N2 nodes. We assessed 585 computed tomography (CT) studies of patients with a primary complex of histoplasmosis, which included the association of single, well-defined, calcified lung nodules and hilar and/or mediastinum calcified lymph nodes. And we made the lymphatic map of the each pulmonary lobes. Results. The lymphatic map disclosed the lymphatic pathways specific for each lobe. The common skip mediastinal station was specific in each lobe: the right lower paratracheal node in the right upper lobe, the subaortic node in the left upper lobe, the pulmonary ligament, and paraesophageal node in the bilateral lower lobes. Skip N2 metastases are uncommon in the right middle lobe. The mediastinum stations involved were as follows: the most commonly involved station was the lower paratracheal node in the right upper lobe, the subcarinal node in the right middle lobe, the subcarinal node in the right lower lobe, the subaortic node in the left upper lobe, and the pulmonary ligament node in the left lower lobe. Conclusions. We classified the current N2 findings into three stages: minimal, early, and advanced N2 disease progression, depending on which level of the lymphatic system is mainly contributing to nodal involvement.

Background. Pseudomesotheliomatous carcinoma of the lung (PMCL) is a disease that resembles pleural mesothelioma. PMCL is characterized by diffuse invasion along the visceral and parietal pleura, and is histologically defined as peripheral lung cancer. Case. A 62-year-old man with right chest pain was referred to our hospital for right pleural effusion. Chest computed tomography revealed right pleural thickening, but no abnormal lung findings. A biopsy specimen obtained during thoracoscopy under local anesthesia showed adenocarcinoma, which was consistent with lung cancer (clinical stage; TXN0M1a: IV). Chemotherapy with carboplatin, pemetrexed, and bevacizumab was initiated. The patient completed 3 cycles of chemotherapy, which suppressed the progression of the disease, while maintaining his performance status. Nevertheless, the lung cancer subsequently progressed. He chose supportive care, and ultimately died 7 months after the diagnosis. Conclusion. We reported a case of PMCL that was diagnosed by thoracoscopy under local anesthesia. PMCL should be included in the differential diagnosis in cases with malignant pleural effusion with no primary tumor in the lung. It is important to make an appropriate diagnosis.

Background. Carcinoma showing thymus-like differentiation (CASTLE) is a rare low-grade neoplasm that arises from ectopic thymic tissue or the remnants of branchial pouches. CASTLE is considered to be an indolent slow-growing neoplasm with a favorable prognosis. Case. The patient was a 75-year-old man who had undergone left thyroid lobectomy 7 years previously. The histological diagnosis was anaplastic thyroid carcinoma. After surgery, he was treated with chemoradiotherapy (60 Gy of external radiation combined with carboplatin and paclitaxel). At 7 years after surgery, chest computed tomography showed a tumor of 14 mm in diameter in the anterior mediastinum. There was no evidence of local recurrence adjacent to the thyroid gland. It was suspected that the tumor was a thymoma or a recurrence of the thyroid neoplasm. We surgically resected the mediastinal tumor via video-assisted thoracoscopic surgery. The mediastinal tumor was cancer and showed squamous epithelial differentiation. The re-evaluation of the previous thyroidectomy specimen revealed that the histological findings of both neoplasms were similar. Immunohistochemical staining revealed that the specimen was focally positive for CD5 and positive for CD117. Based on these findings, the pathological diagnosis of the thyroid lesion was confirmed to be CASTLE, and the tumor of the anterior mediastinum was most likely mediastinal metastasis of CASTLE. Conclusion. CASTLE is a rare tumor that is difficult to differentiate from anaplastic thyroid carcinoma. Accordingly, we should carefully examine the immunohistochemical and pathological findings of such tumors.

Background. Primary choriocarcinoma of the mediastinum is a rare form of extragonadal germ cell tumor that has a poorer prognosis in comparison to other germ cell tumors. In addition, primary choriocarcinoma of the mediastinum most often develops in young men. We encountered a case of primary choriocarcinoma of the mediastinum in what appears to be the oldest patient reported to date. Case. This case involved an 82-year-old woman with left back pain. The patient was found to have a mediastinal mass and pleural effusion. She was diagnosed with primary choriocarcinoma of the mediastinum based on the results of an ultrasound-guided needle biopsy. Chemotherapy with cisplatin and etoposide shrank the tumor and her β-HCG level decreased; however, adverse events precluded the continuation of treatment. The patient died approximately 9 weeks after the diagnosis. Conclusion. Although decreased tolerance of chemotherapy is a problem that needs to be resolved, chemotherapy should prolong survival, even in elderly patients. Although extragonadal germ cell tumors rarely develop in elderly patients, an effective treatment for these tumors should be developed in the future.

Background. Penile metastasis is a rare event, and cases involving penile metastasis of primary lung cancer are extremely rare. Case. We report the case of a 62-year-old man. An abnormality was pointed out on a chest X-ray obtained during postoperative follow-up after stomach cancer treatment. He was diagnosed with lung adenocarcinoma (cT2aN3M0 Stage IIIB), and received chemotherapy. At 5 months after the initiation of chemotherapy, he visited the urology department with a painfully enlarged penis and dysuria. We suspected penile metastasis because FDG positron emission tomography (FDG-PET) showed an abnormal uptake in the penis. A biopsy of the corpus spongiosum revealed adenocarcinoma (the same as the primary lung cancer). His symptoms improved following percutaneous cystostomy, and he underwent chemotherapy again without any major adverse events. He died of lung cancer 5 months after the appearance of penile metastasis. Conclusions. Percutaneous cystostomy was safe and effective for managing the symptoms of penile metastasis.

Background. Although nivolumab is applied as standard second-line chemotherapy for non-small cell lung cancer (NSCLC), it induces many immune-related adverse events (irAEs), including thyroid dysfunction. The various clinical features and pathogenesis of thyroid dysfunction induced by nivolumab are not well defined. Case 1. A 47-year-old man diagnosed with cT1bN2M1b stage IV lung adenocarcinoma underwent surgical resection of brain metastasis followed by several lines of chemotherapy. Nivolumab was initiated as the third line chemotherapy. Case 2. A 66-year-old man relapsed after undergoing surgical resection of cT1bN0M0 stage IB squamous cell carcinoma of the lung. Several lines of chemotherapy were administered; nivolumab was initiated as the fourth line. In both cases, a blood test after the initiation of nivolumab revealed increased levels of free triiodothyronine (FT3), free thyroxine (FT4), and anti-thyroglobulin antibody (TgAb), and decreased levels of thyroid-stimulating hormone (TSH). The clinical findings were consistent with those of silent thyroiditis. Nivolumab therapy was continued and the regression of the tumors was remarkable. Conclusion. Silent thyroiditis is one of clinical features of thyroid dysfunction when only TgAb emerges among the thyroid auto-antibodies induced during nivolumab therapy. Thus, it is recommended that thyroid function test be performed at regular intervals in order to detect the induction of thyroid dysfunction by nivolumab therapy at an early stage.

Background. Lepidic predominant or invasive mucinous adenocarcinoma has been recognized to sometimes show consolidation on chest CT scans. We herein report a case of solid predominant lung adenocarcinoma which spread through the air spaces (STAS) showing air-space consolidation. Case. A 48-year-old man was admitted to our hospital because of hemosputum. A chest computed tomogram showed consolidation in the right upper lung field. Bronchofiberscopy detected bleeding from the right B¹ bronchi, and the observed consolidation was thus considered to be due to aspiration. However, a CT scan taken 1 month later revealed an enlargement of the consolidation, and therefore an operation was performed. The pathologic diagnosis was solid predominant lung adenocarcinoma STAS showing consolidation. Conclusion. This is considered to be a rare case in which consolidation was deemed to be due to alveolar hemorrhaging and cancer cells had diffusely spread through the air spaces.

Background. Combined small cell lung carcinoma (CSCLC) is histologically classified as small cell lung carcinoma (SCLC) containing non-small cell carcinoma. CSCLC mostly contains large cell neuroendocrine carcinoma or adenocarcinoma but rarely contains sarcoma. We report a rare case of CSCLC containing rhabdomyosarcoma. Case. A 75-year-old man with interstitial lung disease was diagnosed with small cell lung carcinoma (SCLC; cT2aN1M1a Stage IV) by bronchoscopy. He received a course of sequential chemotherapy (cisplatin and etoposide) and three courses of sequential chemotherapy (carboplatin and etoposide). The treatment resulted in a partial remission, and the patient was followed up. After eight months, the patient was admitted for progressive dyspnea. Chest computed tomography (CT) showed a diffuse lesion of elevated density in the left lung. He was diagnosed with an acute exacerbation of interstitial pneumonia and was treated with methylprednisolone pulse therapy (1000 mg/day). Despite being given methylprednisolone pulse therapy twice, the patient died of progressive respiratory failure. At autopsy, an examination of the lungs showed that a portion of the SCLC contained multinucleated cells; immunohistochemistry revealed that this region was positive for desmin and myoD1. These results indicated that the multinucleated cells represented rhabdomyosarcoma. Based on the results of a histopathological examination, we diagnosed CSCLC with an element of rhabdomyosarcoma. According to previous reports in the literature, cases of CSCLC containing rhabdomyosarcoma are very rare. Conclusion. It is possible for CSCLC to contain multiple types of cancer. Consequently, it is very important to diagnose CSCLC, in order to select the most appropriate therapy and to estimate the prognosis as accurately as possible.

Background. Resection of pulmonary metastasis from gastric cancer arising from the esophagogastric junction is rarely performed. We resected solitary pulmonary metastasis from esophagogastric junction cancer. Case. A 35-year-old man who had undergone resection of esophagogastric junction cancer 5 years and 3 months earlier presented with a tumor in the left lung on follow-up computed tomography. Although the tumor was suspected of being primary lung cancer, a transbronchial biopsy failed to confirm the diagnosis. Partial resection was performed for a histological diagnosis. The tumor was diagnosed as intermediate differential adenocarcinoma, but whether it was histologically a primary or a metastatic tumor was unknown. Therefore, left lower lobectomy and mediastinal lymphadenectomy were performed, treating the tumor as a primary tumor. The histological diagnosis after the operation was pulmonary metastasis from esophagogastric junction cancer. The patient is alive without recurrences for 2 years and 6 months since the pulmonary resection. Conclusion. A solitary pulmonary metastasis arising from upper third gastric cancer (including esophagogastric junction cancer) may result from direct hematogenous metastasis through the esophageal venous plexus, azygos vein, and superior caval vein, rather than through the liver.

Background. Tracheobronchial anomalies are rare. Therefore, relatively few malignant neoplasms resulting from these anomalies have been identified. Case. The patient was a 60-year-old man who complained of hemosputum. Flexible fiberoptic bronchoscopy showed the right upper bronchus originating from the right wall of the lower trachea (tracheal bronchus) and edematous changes causing reddening of the thickened inferior wall. A biopsy was performed, and the lesion was diagnosed as squamous cell carcinoma. No evidence of distant or lymph node metastases was found. Therefore, the patient was scheduled for surgery. The operation was performed via posterolateral thoracotomy. In addition to right upper lobectomy, tracheoplasty was necessary for the tumor on the tracheal bronchus wall. We performed tracheal wedge resection between the proximal tracheal cuff of the double lumen tube and the distal bronchial cuff. This made it unnecessary for an anesthesiologist to control the airway, with no need for intubation of the surgical field to maintain ventilation. The patient recovered uneventfully with good healing of the trachea and bronchial anastomosis and has enjoyed a good social life without recurrence in the three years since the surgery. Conclusion. We encountered a rare case of tracheal bronchus type lung cancer treated with wedge tracheoplastic lobectomy. Bronchial abnormalities are relatively infrequent but should be recognized accurately in order to determine the optimum surgical procedure.