We examined whether it is possible to identify the primary site by ctDNA analysis by blood sampling (liquid biopsy) for cancer cases of unknown primary. Before initial treatment, liquid biopsy was performed with ctDNA extraction blood collection tubes. Methylation-ctDNA analysis using bisulfite-treated ctDNA as a template revealed that all three genes (CALML5, DNAJC5J, and LY6D) were methylated in cases that were positive for p16 immunostaining in neck lymph node lesions. Methylation-ctDNA analysis, therefore, has applications in determining primary site tumors, and could serve as an alternative method for unknown primary cancer screening. Liquid biopsy is the sampling and analysis of non-solid biological tissue often through rapid and non-invasive methods, which allows assessment in real-time of the temporal heterogeneity of cancer. Its current role is in identifying biomarkers that might contribute to therapeutic decision-making and tools to change the healthcare system.

Since crico-tracheostomy was first reported by Kano et al., many case reports of this technique in adult patients have been published. On the other hand, reports of this procedure in pediatric cases are rare. In this report, we describe a pediatric case in which crico-tracheostomy was performed for a giant tumor associated with neurofibromatosis type I, which made a tracheostomy difficult, with a good long-term outcome. The patient was a 9-year-old boy with multiple tumors in the neck and cervical spine due to neurofibromatosis type I. Although surgical fixation of the cervical spine was necessary due to cervical spinal cord compression fracture and atlantoaxial subluxation caused by the tumor, it was decided to prioritize surgical airway management due to narrowing of the pharyngeal cavity and airway stenosis caused by pressure from the neck tumor. The trachea was displaced to the left due to pressure from the tumor, and the posterior bending of the cervical spine also ran closely parallel, making the usual tracheostomy difficult. Therefore, crico-tracheostomy was performed under general anesthesia. It is known that granuloma formation in the trachea is more likely to occur in pediatric patients than in adults during tracheostomy procedures. However, in this case, there was no granuloma formation and the patient was in good condition 14 months after surgery. However, it is necessary to continue monitoring the long-term effects on laryngeal growth and vocal function.

The pathogenesis of subglottic stenosis remains largely unknown. In addition to developing as a sequela of infection, trauma, or endotracheal intubation, there are also idiopathic cases in which the cause cannot be determined. Idiopathic subglottic stenosis is difficult to treat radically and often requires long-term treatment. In this study, we performed cricoid resection, first tracheal ring circumcision, end-to-end anastomosis of the cricoid and trachea, and cricoid cutaneous fistula for subglottic stenosis suspected to be associated with IgG4-related disease, and obtained a favorable prognosis. The patient was diagnosed as idiopathic because there was no underlying disease or medical history, but histopathological diagnosis suggested the possibility of an IgG4-related disease. In the treatment of subglottic stenosis, it is important to properly diagnose the pathology of the stenosis and select the appropriate surgical technique from among various surgical techniques.

The symptoms of mild cases of upper airway obstruction due to pharyngeal stenosis may improve with conservative treatment, such as nasal airways and noninvasive positive pressure ventilation ; however, tracheostomy is required in severe cases. As there is no severity classification for pharyngeal stenosis, objectively determining its severity is difficult. Therefore, to clarify the factors that cause severe symptoms and influence prognosis, we retrospectively examined the causes, prognosis, and outcome of 17 cases of pharyngeal stenosis that required tracheostomy at our hospital. The scores were assigned as follows : 1 point was given for nasal, nasopharyngeal, or oropharyngeal stenosis ; 2 points for laryngomalacia, tracheomalacia, central apnea, or neurological disease ; and 3 points for pulmonary disease or dysphagia. The scores of patients who were successfully decannulated were 1-4, whereas those of patients who could not be decannulated were 4-13. Notably, the scores of the patients who were decannulated were significantly lower than those of the patients who were not decannulated. Patients with scores of ≥8 tended to require ventilator management. Moreover, dysphagia significantly prevented decannulation. This scoring system may help determine the treatment strategy for respiratory disorders in patients with pharyngeal stenosis.

Here we report a case of tracheal adenoid cystic carcinoma with severe airway stenosis due to airway granulation, without physical stimulation by the stent after endobronchial stenting for adenoid cystic carcinoma. The patient was a 43-year-old woman. In March two years prior to her first visit, she noticed pharyngeal discomfort, followed by persistent cough and dyspnea, and she was referred to our department for further testing and treatment in April of the following year. Plain chest computed tomography (CT) showed thickening of the tracheal wall and a mass protruding into the right side of the tracheal lumen, and positron emission tomography-CT showed uptake in the right side of the trachea. Endobronchial biopsy revealed severe stenosis of the tracheal lumen, so an Ultraflex-covered stent was placed in the protruding mass. Primary adenoid cystic carcinoma of the trachea was diagnosed by pathological examination. Intensity-modulated radiation therapy (66 Gy) was performed and progress was monitored. After about 1 year, the patient's cough had worsened and CT showed worsening airway stenosis caudal to the stent. As the stenosis was severe, the patient was intubated and placed on a ventilator. She was later extubated under extracorporeal membrane oxygenation and two additional Ultraflex-covered tracheal stents were placed cranial and caudal to the existing stent. Biopsy of the area at that same time showed inflammatory granulation tissue but no malignant cells.

Excessive dynamic airway collapse (EDAC) is a condition in which chronic inflammation or irritation of the trachea or main bronchi leads to increased vulnerability of the posterior membrane, causing tracheal stenosis by protrusion of the posterior membrane into the tracheal lumen during expiration. In this report, we describe a case of EDAC caused by deep neck abscess and tracheostomy. An emergency tracheostomy was performed for upper airway obstruction due to a right deep neck abscess. The patient was treated conservatively with systemic antibacterial therapy for deep neck abscess and initially showed a tendency toward improvement, but on the 4th day of treatment, a rapid deterioration of respiratory condition was observed. Fiberscopy and CT scan of the cervicothoracic region revealed protrusion of the posterior membrane of the trachea into the tracheal lumen during expiration, which led to the diagnosis of EDAC. The respiratory condition was stabilized by CPAP therapy with noninvasive positive pressure ventilation, and the patient was weaned from the ventilator on the 9th day of treatment, and the tracheal cannula was removed on the 14th day. In this case, chronic irritation of the trachea and bronchi due to long-term smoking was the underlying cause, and EDAC was most likely induced by acute inflammation due to a cervical abscess, tracheostomy, and tracheal cannula. We believe that the presence of EDAC should be kept in mind when treating dyspnea in adults.