Foreign Body Reaction Mimicking Lymph Node Metastasis is Not Rare After Lung Cancer Resection.

Background:  Mediastinal lymphadenopathies with high 18-fluorodeoxyglucose uptake in patients previously operated on for lung cancer are alarming for recurrence and necessitate invasive diagnostic procedures. Peroperative placement of oxidized cellulose to control minor bleeding may lead to a metastasis-like image through a foreign body reaction within the dissected mediastinal lymph node field at postoperative examinations. In this study, we investigated clinicopathological features and the frequency of foreign body reaction mimicking mediastinal lymph node metastasis.

Methods:  Patients who underwent surgery for lung cancer between January 2016 and August 2021 and who were subsequently evaluated for mediastinal recurrence with endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) were included. Patients were grouped according to the results of EBUS-TBNA as metastasis, foreign body, and reactive. Clinicopathological features of these patients were compared and characteristics of patients in the foreign body group were scrutinized.

Results:  EBUS-TBNA was performed on a total of 34 patients during their postoperative follow-up due to suspicion of mediastinal recurrence. EBUS-TBNA pathological workup revealed metastasis in 18 (52.9%), foreign body reaction in 10 (29.4%) and reactive lymph nodes in 6 (17.6%) patients. Mean maximum standardized uptake value (SUVMax) for metastasis group and foreign body group were 9.39 ± 4.69 and 5.48 ± 2.54, respectively (p = 0.022). Time interval between the operation and EBUS-TBNA for the metastasis group was 23.72 ± 10.48 months, while it was 14.90 ± 12.51 months in the foreign body group (p = 0.015).

Conclusion:  Foreign body reaction mimicking mediastinal lymph node metastasis is not uncommon. Iatrogenic cause of mediastinal lymphadenopathy is related to earlier presentation and lower SUVMax compared with metastatic lymphadenopathy.