Recently, there have been scattered reports of patients with empyema without any underlying diseases. Some reports have indicated that oral bacteria play a role in the onset of this disease. This study included 31 patients with acute empyema who underwent thoracoscopic drainage in our hospital between 2012 and 2022. Here, we mainly focused on acute empyema caused by odontogenic infection and retrospectively summarized and evaluated clinical and microbiological factors in these patients. Among the 31 patients, 7 (22.6%) reported acute empyema caused by odontogenic infection, which was in line with the results observed in previous studies (12.0-33.3%). These seven patients did not have a history of diabetes or oral steroid use, and most of them did not receive treatment for caries or severe periodontitis. This study supports the suggestion that odontogenic infection may cause acute empyema in some patients. Therefore, in patients with acute empyema, it is important to consider their medical history including oral hygiene, recognize the importance of oral care, and implement daily activities for the prevention of odontogenic infection.

A 57-year-old Japanese woman was referred to our hospital after a 25-mm nodule in the left lower lung lobe and a 30-mm tumor in the anterior mediastinum were detected by CT at another hospital. The lung tumor was diagnosed as adenocarcinoma by trans-bronchial lung biopsy. The mediastinal nodule was suspected to be lymph node metastasis or a mediastinal tumor. There was no other lymph node metastasis, and solitary anterior mediastinal lymph node metastasis is very rare. A mediastinal tumor was thus suspected, and we performed a thoracoscopic left lower lobectomy and mediastinal tumor resection. Pathological findings revealed that both tumors were enteric adenocarcinoma. Immunohistochemical findings were: CK20 (+), CDX2 (+), CK7 (−), TTF-1 (−). Colonoscopy showed no malignancy, and we made a diagnosis of pulmonary enteric adenocarcinoma (pT2bN2M0 stage IIIA). Three months after the surgery, lung and brain metastases were detected. Chemotherapy was administered but the patient died at 14 post-operative months. We provide the details of this surgical case of pulmonary adenocarcinoma with enteric differentiation and solitary mediastinal lymph node metastasis.

A 73-year-old woman was injured in a car accident, in which she was a passenger. Computed tomography (CT) showed multiple bilateral rib fractures, mild left hemopneumothorax, and traumatic liver injury, although she had no head injury and her consciousness was clear. On the second day, her chest radiograph showed progression of left hemopneumothorax, and left thoracic drainage was performed. However, on the third day, she developed seizures and impaired consciousness. A markedly decreased level of serum sodium was noted, which had been in the normal range on admission, and there was no evidence of disease involving the central nervous system or adrenal dysfunction. Thus, we diagnosed her with syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Serum sodium levels rapidly normalized with electrolyte correction, and consciousness improved. She was discharged from the hospital on the 14th day. Although there are a few reports of SIADH occurring after tumor-associated syndrome or lung cancer surgery, it may also occur with changes of intrathoracic pressure due to traumatic pneumothorax. Sudden hyponatremia can cause convulsions and impaired consciousness. SIADH should be considered when traumatic pneumothorax occurs and consciousness is impaired.

A 47-year-old woman complaining of shortness of breath was referred to our hospital from a nearby clinic. Computed tomography (CT) revealed multiple bilateral pulmonary cysts and bilateral pneumothorax, which were more marked on the right. Chest drains were inserted bilaterally, but the pneumothoraxes did not improve. Thus, the pulmonary cyst in the right lung was resected using video-assisted thoracic surgery. Based on the evidence of bilateral multiple pulmonary cysts, lymphangioleiomyomatosis (LAM) was suggested as a differential diagnosis.

However, immunostaining of the resected pulmonary cysts did not reveal LAM. The patient had a history of dermal surgery for hamartomatous lesions, including a fibrofolliculoma on the lower jaw removed 4 years previously. Birt-Hogg-Dubé (BHD) syndrome was suspected, despite no personal or family history of the disease. Genetic testing revealed the presence of a pathogenic variant in exon 11 of FLCN, leading to a diagnosis of BHD syndrome. Our findings highlight the importance of genetic testing based on clinical features even in cases with no family history of the disease, as long as the patient provides informed consent.

The patient was a 52-year-old man who underwent a thoracoscopic left lower lobectomy and two partial left upper lobe resections at a previous hospital for colorectal cancer metastasis. He was admitted to our hospital due to recurrence in the surgical margin. The images showed that the recurrent tumor and lung resection line were in close contact. Furthermore, considering that the mediastinal pleura surrounding the aorta had been resected at the time of the previous surgery, it was determined that the recurrent site had infiltrated or adhered to the aortic wall. An aortic stent graft was inserted before lung resection so that it could be performed safely. Although marked adhesions between the S¹⁺² segment and descending aorta were observed intraoperatively, as expected, we were able to safely dissect the aortic stent and resect the S¹⁺² segment as planned. The patient was discharged on postoperative day 14. After one and a half months, he was knocked over by a dog and developed back pain. On CT, the patient was found to have Stanford type B acute aortic dissection, the entry of which was at the proximal end of the aortic stent graft. He improved with conservative treatment and blood pressure control. From our above-mentioned experience, the risks and benefits of preoperative aortic stent graft placement need to be carefully examined in lung surgery.

A man in his 40s was referred to our hospital due to abnormal findings on a chest radiograph during a health examination. Subsequent computed tomography demonstrated a lobulated mass, 10 cm in diameter, in the anterior mediastinum close to the right atrium. The patient underwent complete resection of the suspected anterior mediastinal tumor. The mass was firmly adhered to the pericardium, and when the pericardium was incised and pericardial sac was observed, the tumor was cockscomb in form and protruded into the pericardial cavity. Since invasion into the pericardium was suggested, this was also resected. Based on the histological findings and immunostaining, the tumor was diagnosed as a solitary fibrous tumor (SFT).

SFTs are often depicted as a smooth-surfaced mass with well-defined borders on imaging and are often observed as a smooth-surfaced mass by macroscopy. To our knowledge, this is the first report of a cockscomb form protrusion toward the pericardial lumen; we consider this case to be a valuable example of an SFT with various clinical features.

A 32-year-old man was transferred to the emergency department with a complaint of sudden left chest pain. He had been diagnosed with neurofibromatosis type 1 at one year of age. Chest CT showed a left tension hemothorax, and he was in shock. Therefore, emergency surgery was performed to stop the bleeding, and arterial bleeding was observed near the left subclavian artery in the thoracic cavity. However, hemostasis was difficult to achieve because of the fragility of the vascular tissue. Percutaneous angiography was performed with gauze packing to control bleeding. It revealed extravasation of the contrast agent from the internal thoracic artery, and transcatheter arterial embolization (TAE) was performed. He recovered with a good course, but on the 12th hospital day, he suddenly developed a bulge and pain in his left neck. Emergency percutaneous angiography was performed to detect re-bleeding from the cervical artery. This indicated bleeding from the left vertebral and thyrocervical arteries. TAE was performed at the same site to prevent bleeding. Although vascular tissue fragility and arterial hemorrhage are rare in neurofibromatosis type 1, it is imperative to initiate treatment as soon as feasible.

A four-year-old boy presented with vomiting as the chief complaint. Chest CT showed a mass with calcification in the right middle lobe of the lung. Mediastinal teratoma or pulmonary hamartoma was suspected. Hence, right middle lobectomy was performed under video-assisted thoracic surgery for diagnostic treatment. Pathological findings were negative for both neoplastic lesions and inflammatory lung lesions, and the lesions were considered to be related to congenital cystic lung diseases; however, the case was atypical. Congenital cystic lung disease includes various lesions, and there are some cases in which a definite diagnosis is difficult owing to the presence of multiple lesions resulting from their embryological characteristics.

Empyema necessitans occurs when the contents of empyema penetrate the chest wall and form an abscess in tissue surrounding the thoracic cavity. Chronic infection with Mycobacterium tuberculosis and actinomycetes is often reported as the cause. We encountered a case of empyema necessitans caused by Porphyromonas gingivalis. The patient was a 72-year-old woman. She noticed a subcutaneous mass growing on the left side of her abdomen and consulted a local doctor. Computed tomography and magnetic resonance imaging showed left empyema and subcutaneous fluid accumulation in the left flank, leading to a diagnosis of empyema necessitans. During the early stage of hospitalization, we performed empyema thoracotomy, chest drainage, and subcutaneous abscess drainage. P. gingivalis is the causative bacterium of periodontal disease. It has marked proteolytic enzyme activity because it uses protein degradation products as a nutrient source. Therefore, it is likely to induce severe abscess formation. In the present report, we describe the favorable results obtained by surgical treatment and provide a review of the literature.

We performed thoracoscopic surgery in a prone position, offering a better visual field, for a superior posterior mediastinal cyst bordering on the bilateral thoracic cavity. Thoracoscopic surgery in a prone position is mainly used in surgery for the esophageal region. The combination of the prone position and artificial pneumothorax improves the intraoperative field of view. A man in his 60s visited a medical institution complaining of nocturnal chest tightness. Chest computed tomography (CT) and magnetic resonance imaging (MRI) revealed a superior posterior mediastinal cyst that compressed the trachea and esophagus. Because the tumor was primarily located in the left mediastinum but was also adjacent to the aortic arch, we performed thoracoscopic surgery using carbon dioxide insufflation in the prone position. Intraoperatively, marked adhesion between the cyst and esophagus was observed, but the cyst was safely resected with a good working space obtained by positioning and insufflation. Histopathologically, the primordium was unknown, but cystic lymphangioma was suggested based on the clinical course and intraoperative findings. No postoperative complications, including chylothorax, were observed.

Surgery in a prone position for a superior posterior mediastinal cyst adjacent to the bilateral thoracic cavity can expand the working space and prevent sinking of the cyst into the contralateral thoracic cavity, which enables safe surgery by preventing hemorrhagic complications due to improvement of the intraoperative field of view during resection close to the contralateral thoracic cavity.

A 50-year-old man was referred to our hospital for surgery due to a mass in the right lower lobe discovered on CT during a medical checkup, which had been increasing in size for 15 years. After follow-up CT revealed a mass and nodules in the right lower lobe, we performed video-assisted thoracoscopic surgery (VATS) right lower lobectomy. The mass had a vesicular, sponge-like appearance and histologically showed placental villus-like structures. The pathological diagnosis was placental transmogrification of the lung (PTL). At six months after the surgery, the patient showed no signs of recurrence.

The patient was a 73-year-old man admitted to our hospital for the treatment of squamous cell carcinoma of the lung. On admission, he was unconscious, dehydrated, and had renal dysfunction. Laboratory tests revealed high levels of parathyroid hormone-related protein (PTHrP) and serum calcium. He was therefore diagnosed with hypercalcemia-induced disturbance of consciousness resulting from PTHrP-producing lung cancer. Since the patient's general condition was poor, treatment for lung cancer was considered inadvisable, and treatment for hypercalcemia was initiated. The patient's symptoms improved after the administration of infusions, diuretics, and calcitonin and, subsequently, right lower lobectomy and ND2a-1 lymph node dissection were performed. At the 26-month follow-up after surgery, the patient was alive and without recurrence of the cancer.

Lung cancer patients with hypercalcemia and psychiatric symptoms or renal failure reportedly have a poor prognosis. In the present case, the patient had a poor general condition with impaired consciousness. However, radical resection was possible once the hypercalcemia had been resolved. We propose that the resolution of hypercalcemia in lung cancer patients can improve their condition sufficiently to allow the cancer to be successfully treated.

Chest radiograph of a 63-year-old female showed atelectasis of the left lung, while chest CT showed a tumorous lesion in the left main bronchus and atelectasis of the left whole lung. Due to hypoxemia (62% SpO₂ in room air), mechanical ventilation following tracheal intubation was initiated. Fiberoptic bronchoscopy revealed a visible tumor completely occluding the left main bronchus, and a histological diagnosis of pulmonary mucoepidermoid carcinoma was obtained through transbronchial biopsy. We performed left pneumonectomy via open thoracotomy based on improvement of the PaO₂/FiO₂ ratio from 208 to 420 with the left pulmonary artery occlusion test. This surgery was performed due to concerns of postoperative complications caused by preoperative obstructive pneumonia and the remaining Methicillin-resistant Staphylococcus aureus-infected lung, detected in sputum. Oxygenation was improved and the patient was discharged on postoperative day 24 with an uneventful clinical course. Pneumonectomy is effective in pulmonary mucoepidermoid carcinoma patients requiring mechanical ventilation due to whole atelectasis of the hemilateral lung. Improvement of oxygenation base on a pulmonary artery occlusion test, led by the resolution of ventilation-perfusion mismatch, could be a rationale to indicate pneumonectomy.

A 56-year-old woman presented at our hospital with dyspnea and weight loss. Computed tomography showed a giant mass in the anterior mediastinum and both thoracic cavities, which was about 30 cm in diameter. We diagnosed the mass as liposarcoma, and planned resection based on radiological findings. We prepared extracorporeal membrane oxygenation to avoid ventilation failure and circulatory collapse at the introduction of general anesthesia and during surgery. The tumor was completely resected by clamshell incision, measured 38 cm, and weighed 2855 g, pathologically diagnosed as dedifferentiated liposarcoma. She has been followed up for two years since surgery without recurrence.