Background: According to the Revised Atlanta classification[1], walled-off pancreatic necrosis (WOPN) is a mature, encapsulated necrotic collection that develops≥4 weeks after necrotizing acute pancreatitis (AP), occurring in 1%–9% of cases overall and up to 15% of cases of severe AP.

Aim: To analyze the body composition of these patients with different tools available at our Institute.

We collected demographic and anthropometric data—including weight, height, body mass index (BMI), Bioelectrical Impedance Analysis (BIA), hand-grip strength (dynamometry,) and the Malnutrition Universal Screening Tool (MUST)—from 64 patients treated for WOPN at our Institute between May 2022 and November 2025, retrospectively. These measures were used to evaluate body composition and malnutrition risk. Two groups were formed based on treatment type: endoscopic ultrasound (EUS)-guided lumen-apposing metal stent (LAMS) insertion (n=42) versus conservative (n=22). 

Among the 64 patients, 41 (64.06%) were male (28 (66.67%) and 13 (59.09%) in the intervention and the conservative group, respectively). The median age was 54.5 years (56.5 and 50.5 years, respectively). BIA was performed in 21 LAMS (50%) and 12 conservatively treated patients (54%). The mean extracellular water  (ECW) ratio was 0.396 in the LAMS group and 0.388 in the conservative group, respectively (67% of LAMS patients and 50% of conservative patients had a high ECW ratio). These elevated ECW ratios, due to fluid collections, substantially distorted BIA-derived muscle parameters (FFMI, SMI, and skeletal muscle mass), indicating that BIA is not a reliable method for assessing body composition in WOPN patients. Hand-grip strength was assessed in 11 LAMS patients: 82% (n=9) showed weak grip strength, and 18% normal values. In contrast, among 16 conservatively treated patients, only 31% (n=5) showed weak grip strength, while 44% (n=7) had normal and 25% (n=4) strong measurements. MUST scores indicated higher malnutrition risk in the LAMS group (n=32): 41% low, 13% moderate, and 47% high risk. In the conservative group (n=21), the majority had low risk (76%), while only 10% and 14% were classified as moderate and high risk, respectively. Overall, LAMS patients demonstrated poorer general condition, weaker muscle strength, and higher malnutrition risk, likely related to longer hospitalization and greater weight loss from impaired oral intake

Nutritional monitoring in WOPN—especially in interventional (LAMS) patients—is crucial due to their high risk of malnutrition and sarcopenia. As BIA results are confounded by fluid collections, CT-based body composition assessment is more reliable. Optimal care requires a multidisciplinary team comprising physiotherapists, dietitians, and psychologists; future randomized studies are needed to refine management strategies.