Reaction patterns of the tracheobronchial wall to implanted noncovered metal stents

Endoluminal implantation of stents has evolved as a nonsurgical treatment option for stenosis of the central airways. Based on the favorable results in treatment of tumorous tracheobronchial stenosis, stenting has been introduced into the therapy of nonmalignant stenosis.

To study the long-term biocompatibility and incorporation of implanted bronchial stents based on the pathoanatomic reaction of the tracheobronchial system in humans. The incorporation of bronchial stents was documented, with specific interest in transformation or induction of dysplasia in the implantation zone.

The tracheobronchial reaction was studied in 18 patients 2 days to 18 months after implantation of 24 noncovered metal stents (Wallstent; Schneider; Bülach, Switzerland; n = 8; and Ultraflex; Boston Scientific; Natick, MA; n = 16).

Stenting produced slow papillomatous growth of granulative tissue through the interfilamentary space of the stents. A nonspecific inflammatory response of nontumorous tissue could be documented. Sparse spots of superficial squamous cells occurred. No epithelial dysplasia or giant cells were detected within the stented region. The number of superficial ciliated cells in the implantation zone was markedly reduced.

After stent insertion in the upper airways, no malignant transformation of initially nontumorous tissue occurs. Stenting seems to be a safe therapy option when considered even for nonmalignant airway stenoses.