Two cases of granuloma mimicking local recurrence after pulmonary segmentectomy

Fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT is the most sensitive non-invasive imaging method for the detection of tumor metastasis and recurrence, but sometimes reveals false-positive results. Herein, we report two cases of false-positive results on PET/CT scans along with elevated serum carcinoembryonic antigen (CEA) levels, mimicking local recurrence after pulmonary segmentectomy.

Case 1; A 75-year-old woman underwent thoracoscopic left basal segmentectomy for primary lung cancer. Follow-up at 6 months after the surgery revealed serum CEA level elevation and chest CT showed a nodule measuring 25 × 22 mm in the residual left lower lobe. PET/CT revealed FDG uptake in the nodule diagnosed as local recurrence of lung cancer, and the patient underwent partial resection of the nodule. Microscopic examination of the resected specimen revealed granuloma caused by polyglycolic acid (PGA) sheet. Case 2; A 58-year-old man underwent VATS right S1 segmentectomy for lung metastasis from rectal carcinoma. Serum CEA levels gradually increased after surgery, and PET/CT revealed FDG uptake in the stump diagnosed as local recurrence of the lung metastasis. The patient underwent completion lobectomy 6 months after the segmentectomy, and the pathology of the resected specimen revealed an inflammatory granuloma caused by PGA suture.

Although suture and stapler granulomas have been reported, granuloma caused by PGA sheets has never been reported. Postoperative recurrence of lung cancer should be diagnosed with not only PET/CT scans and serum tumor markers but also pathological findings, to avoid unnecessary treatment such as chemotherapy, radiation, and difficult reoperation.