Mycobacterial granuloma on the staple line after pulmonary resection

Objective It has been reported previously that granulomas can occur around nonabsorbable sutures, but that granuloma formation around the staple line is very rare. However, the increased use of thoracoscopic surgery is creating more opportunities to use automatic mechanical suturing equipment for pulmonary surgery, and it is expected that the incidence of granuloma around the staple line will increase. Methods We retrospectively investigated the clinical records of 6 patients who developed nontuberculous mycobacterial granuloma on the staple line after pulmonary resection. We investigated their clinical characteristics and compared them with data in 16 cases of cancer recurrence. Results Fluorodeoxyglucose uptake was detected in all 6 patients. Laboratory data including white blood cell counts and C-reactive protein levels were within normal ranges in all patients. There was no evident tendency in terms of age, sex, maximal standardized uptake value, or radiological findings. However, compared to cancer recurrence, mycobacterial granuloma around the staple line appeared after a longer period of time, and the proportion of patients who had a segmentectomy as the initial surgery was significantly higher. Conclusion When growing shadows are observed near the staple line, it is difficult to differentiate between cancer recurrence and nontuberculous mycobacterial granuloma from computed tomography and laboratory findings. However, if a mass shadow around the staple line appears 2, 3, or more years after segmentectomy, it could be considered likely to be a granuloma. "Post-segmentectomy" and "late occurrence" are important attributes for distinguishing staple line granuloma from cancer recurrence.