Predicting ICG fluorescence uptake in laparoscopic lymphoma biopsy: the role of a 20 mm node size cut-off

This study investigated the correlation between lymph node (LN) size, histopathological architecture, and intraoperative fluorescence in patients undergoing Fluorescence-Guided Laparoscopic Lymph Node Biopsy (FGLLB) for suspected lymphoma. Between April 2022 and September 2025, 32 patients with sub-mesocolic aortic and iliac lymphadenopathy underwent FGLLB for disease staging purposes or to establish a diagnosis. The degree of intraoperative fluorescence was recorded and correlated with LN size and microscopic findings. A Receiver Operating Characteristic (ROC) curve analysis was performed to determine the predictive value of LN size on fluorescence uptake and to identify an optimal dimensional cut-off. Biopsies were excisional in 15 patients, incisional in 12, and 5 had both types. A total of 53 lymphatic tissue samples were analyzed. Fluorescent LNs were significantly smaller than non-fluorescent ones (p = 0.019). ROC curve analysis revealed an Area Under the Curve (AUC) of 0.74 (95% CI: 0.58-0.90). An optimal dimensional cut-off of 20 mm was identified for predicting fluorescence failure, yielding a sensitivity of 85% and a specificity of 67%. Microscopic examination confirmed that non-fluorescence in nodes > 20 mm was strictly associated with total architectural effacement, whereas fluorescence was preserved in larger nodes only when the follicular structure remained intact. This study identifies a significant correlation between LN size and ICG uptake, suggesting a 20-mm threshold beyond which architectural disruption appears to impair fluorescence. Although these findings require validation in larger cohorts to ensure generalizability, they provide a valuable roadmap: while ICG excels for small occult nodes, surgeons should prioritize anatomical landmarks and preoperative imaging for bulky disease > 2 cm.