Staple Line Thickening After Sublobar Resection: Reaction or Recurrence?

Background: Stapling across lung parenchyma may lead to tissue granulation, which could be confused radiographically with recurrence. We sought to define the time course and radiographic characteristics of such thickening and to determine their association with recurrence.

Methods: Patients who underwent limited resection for non-small cell lung cancer were included. Surveillance computed tomography scans were reviewed to characterize the morphology and size of staple line granulation tissue. Radiological and clinical findings were analyzed and univariate predictors of recurrence were examined.

Results: We characterized 78 patients for tissue granulation a total of 314 times in serial scans. On initial postoperative scans, 3.8% (n = 3) of staple lines showed no thickening and 17.9% (n = 14) showed thickening less than 2 mm, whereas 78.2% (n = 61) showed thickening 2 mm or greater. Of the 75 staple lines with thickening, soft tissue was characterized as linear in 32.0% (n = 24), focal along the pleura, hilum, or parenchyma in 24.0% (n = 18), and nodular in 44.0% (n = 33). Subsequent scans revealed that 25.3% of these areas (n = 19) did not change in shape or size over time, 58.7% (n = 44) showed regressive changes, and 16.0% (n = 12) showed progressive changes, the thickening of which in all 12 of these patients showed an increase in the largest dimension by 2 mm or greater. Among the 78 patients, 7.7% (n = 6) had biopsy-proven recurrence along the staple line. An increase in the largest dimension by 2 mm or greater (83.3% versus 9.7%; P = .001) and radiologic concern for malignancy (66.7% versus 11.1%; P = .001) predicted staple line recurrence.

Conclusions: Staple line thickening is a frequent occurrence after pulmonary limited resection, but rarely indicative of recurrence. The characteristics and initial size of granulation tissue do not predict recurrence. Increases in tissue 2 mm or greater at the staple line over time predict local recurrence, which typically occurs after a prolonged time interval.