Biogeography of the Respiratory Tract Microbiome in Patients With Malignant Tracheal Tumors

BackgroundThis study aimed to characterize the bacterial microbiota in the oral cavity (OC), throat, trachea, and distal alveoli of patients with primary malignant tracheal tumors (PMTT), including squamous cell carcinoma (SCC) and salivary gland carcinoma patients (SGC), for comparison with a matched non-malignant tracheal tumor (NMTT) group.MethodsPatients with pathological diagnosis of PMTT and NMTT were included in this study. Saliva, throat swab (TS), trachea protected specimen brush (PSB), and bronchoalveolar lavage fluid (BALF) samples were collected for 16S rRNA gene sequencing. The composition, diversity, and distribution of the microbiota were compared among biogeographic sampling sites and patient groups. The relationship between the genera-level taxon abundance and tracheal tumor types was also investigated to screen for candidate biomarkers.FindingsThe most represented phyla in the four sites were Bacteroidetes, Firmicutes, Proteobacteria, and Fusobacteria. In SCC patients, the relative abundance of Bacteroidetes and Firmicutes gradually decreased with increasing depth into the respiratory tract, while the relative abundance of Proteobacteria gradually increased. Bacterial communities at the four biogeographic sites formed two distinct clusters, with OC and TS samples comprising one cluster and PSB and BALF samples comprising the other group. Principal coordinate analysis showed that trachea microbiota in SCC patients were distinct from that of SGC or NMTT patients. In the trachea, AUCs generated by Prevotella and Alloprevotella showed that the abundance of these genera could distinguish SCC patients from both NMTT and SGC patients.InterpretationThe structure of respiratory tract microbiota in PMTT patients is related to tumor type. Certain bacteria could potentially serve as markers of SCC, although verification with large-sample studies is necessary.

Recurrent tracheal tumor with a critical airway requiring ‘Y’ stent – unique presentation of tuberculosis

Tracheal tumor is a rare entity. Tracheal tumor may be a primary tracheal tumor or secondary to invasion from a mediastinal tumor (or a lymph node). These tumors are prone to cause critical airway obstruction which may require urgent care. Tuberculosis is one of the common differential diagnoses of mediastinal lymphadenopathy in TB endemic countries, though isolated tuberculous mediastinal lymphadenopathy without a lung involvement is rare. We report an extremely rare case of isolated paratracheal lymphadenitis due to tuberculosis, eroding the trachea and presented a lower tracheal tumor, which recurred again after complete debulking. Finally, the disease required a ‘Y’ stent placement, to stabilize the airway following the second recanalization. We discuss the incidence, differential diagnosis, and the bronchoscopic, interventional aspects of this entity.

Adenomatous hyperplastic intratracheal ectopic thyroid tissue: a case report

Intratracheal ectopic thyroid (ITET) is a rare disease, with limited cases reported in the literature. ITET is an unusual congenital abnormality and can be easily mistaken for a respiratory illness. We present a case of a 61-year-old man with a history of slight discontinuous hemoptysis for 2 years. A tracheal mass, which appeared to be connected to the left thyroid gland, was found by chest computed tomography scan. Ultrasound revealed one suspiciously malignant, solid and hypoechoic nodule in the left thyroid gland. After the thyroid origin of the mass was confirmed by bronchoscopic biopsy, the patient underwent segmental resection and anastomosis of the trachea, together with left thyroidectomy. Histopathology of the tracheal tumor showed adenomatous hyperplastic ITET, and the orthotopic left thyroid gland showed nodular goiter with atypical adenomatous hyperplasia. Clinical suspicion is warranted in patients presenting with a tracheal tumor seemingly connected to the thyroid gland, particularly in patients who have imaging features suggestive of a malignant tumor in the orthotopic thyroid but without confirmative histopathology of malignancy before surgery.