Nodule around the staple line after pulmonary resection: benign granuloma or cancer recurrence?

When a mass develops around the staple line after lung cancer surgery, differential diagnosis between lung cancer recurrence and benign granuloma can be clinically problematic. Therefore, we investigated the clinical characteristics of benign granuloma and cancer recurrence around the staple line to determine clinical factors that can distinguish staple line granuloma and cancer recurrence.

We retrospectively investigated the clinical records of 25 patients who developed a nodule around the staple line after pulmonary resection for lung cancer and conducted a comparative study of staple line granuloma and cancer recurrence.

Among 25 patients, the nodule was diagnosed as benign granuloma in 9, recurrence of primary lung cancer in 8, and recurrence of metastatic lung cancer in 8. Among these three groups, there were no significant differences in age, maximum standardized uptake value of fluoro-deoxyglucose, laboratory data, or radiological findings. However, in comparison with the cancer recurrence cases, the proportion of patients who had undergone segmentectomy as initial surgery was significantly higher in the granuloma group. Moreover, in five patients in the granuloma group, mycobacterium was detected.

It seemed difficult to differentiate between cancer recurrence and granuloma on the basis of radiological examination and laboratory findings. However, if a mass shadow around the staple line appeared after segmentectomy, the mass is likely to be a granuloma. Mycobacterial infection may be an important factor for development of granuloma on the staple line.