Fibrillar haemostatic agents mimicking nodal recurrence after thoracic surgery: a cohort study.

OBJECTIVES: Fibrillar haemostatic agents are widely used to control bleeding. However, they may persist post-operatively and induce a foreign body reaction or mimic lymph-node recurrence on different imaging modalities. METHODS: This retrospective cohort study included 11 patients who underwent thoracic surgery for lung or mediastinal malignancy with intraoperative fibrillar haemostatic material and subsequently developed imaging findings suspicious for malignancy recurrence. Patient demographics, tumour characteristics, surgical details, and fibrillar usage were recorded. Imaging findings across CT and PET-CT were analysed. Clinical outcomes, including follow-up interventions and histopathological results, were reviewed. RESULTS: The mean time from surgery to detection of a suspicious lesion was 9.7 months (range 2-24). PET-CT was the follow-up modality in 81.9% of cases, demonstrating increased FDG uptake in 7/9 cases, with SUVmax ranging from 2.0-14.4. FDG uptake and SUVmax values overlapped substantially between benign and malignant lesions, with no threshold reliably distinguishing the two. In all cases, lesions were located at or adjacent to prior surgical sites corresponding to fibrillar placement. 10/11 patients (90.9%) required active intervention beyond imaging surveillance. Histopathology showed benign foreign-body reaction in 7/11, malignant recurrence in 2/11, and both in 2/11 (malignancy present in 4/11 overall). CONCLUSIONS: Fibrillar residues are a recognised and clinically significant mimic of nodal recurrence across imaging modalities, particularly on PET-CT. Recognition of characteristic imaging features and correlation with surgical history are essential to avoid unnecessary invasive procedures. Where tissue diagnosis is required, endobronchial ultrasound (EBUS)-guided biopsy is recommended as the preferred first-line approach before surgical re-intervention.