In thoracic surgery, one of the important concerns that has led to an insistent demand for suture protection is bronchopleural fistula. Risk factors for the development of bronchopleural fistula include advanced cancer stage, preoperative chemotherapy or radiation therapy or both, previous steroid therapy, residual carcinomatous stump, postoperative mechanical ventilation, chronic obstructive pulmonary disease, diabetes mellitus, and malnutrition [3, 4]. The use of Teflon pledgets has been reported to reinforce the bronchial stump and potentially reduce the incidence of bronchopleural fistula, especially in patients who are at an increased risk . Nevertheless, a case of bronchial obstruction owing to the erosion of Teflon pledgets into the airway has been reported previously .
Wound healing of the bronchial stump is characterized by granulation tissue formation with angiogenesis and proliferation of fibroblast cells. During this process, a foreign substance such as a suture can become buried in the connective tissue. Healing of the bronchial stump is not directly attributable to healing of the suture site, but it is achieved secondarily when the bronchial stump is covered with peribronchial tissue. The outer surface of the bronchial stump is covered by connective tissue within 2 weeks, and complete healing with mature fibrous tissue is achieved within 4 weeks . In accordance with this mechanism, suture material for bronchial stump closure is buried in the connective tissue or fibrous tissue but not exposed on the pleural surface. However, there have been cases of infection owing to a foreign substance such as a suture or chronic infection that led to the development of refractory granuloma . The reported suture material-related complications occurring at least 1 year postoperatively include granuloma, hemoptysis, infection, stump fistula, and chronic necrotizing pulmonary aspergillosis [1, 2]. No study other than the present one has reported exposure of the suture material in the bronchial stump at 8 years after lobectomy.
The absorbable suture, which was used in the present case, is safe because the tensile strength is maintained for 2 weeks until the anastomosis site and bronchial stump are covered by connective tissue, although there is a concern for suture failure owing to an early decrease in tensile strength . In the present case, there had been no air leakage from the bronchial stump. Therefore, considering the healing mechanism of the bronchial stump, it might have been necessary to use the Teflon pledget for decreasing tension. However, with that as a cause, our patient developed this complication after lobectomy. The previously reported suture materials related to complications were mostly non-absorbable materials , and the suture material used in the present case was a Teflon pledget, a non-absorbable material.
To prevent late complications, it is desirable to use biological materials such as fat pad, muscle fascia, and pericardium. However, in cases where the wound healing process is not compromised, late complications can be prevented even with non-absorbable suture materials. Regarding the mechanism of translocation of the suture material from the pleural space to the bronchial lumen in the present case, it was hypothesized that the suture with the pledget remaining in the pleural space had been buried in the submucosa of the bronchial wall during the wound healing process after the bronchus was cut. However, it is difficult to prove this hypothesis.