Gallbladder involvement in metachromatic leukodystrophy: a systematic review and comparison of American and European surveillance recommendations

This is the authors' abstract. We don't add key points for this paper.

Background Gallbladder and biliary abnormalities are increasingly recognized extracerebral manifestations of metachromatic leukodystrophy (MLD), but their spectrum, frequency, complications, and surveillance implications remain incompletely standardized. Methods We performed a PRISMA 2020-based systematic review. PubMed/MEDLINE was searched from inception to 12 July 2026 using MLD terms combined with gallbladder, biliary, cholecystic, hemobilia, papillomatosis, polyp, and carcinoma terms. Eligible reports described gallbladder or biliary involvement in MLD or an MLD-like saposin B-deficient phenotype. Results Fifty-one PubMed/MEDLINE records and three additional reports were identified; 37 reports were included. The published evidence comprised 128 individuals with reported gallbladder status, of whom 111 (86.7%) had gallbladder abnormalities. Reported findings included wall thickening, inflammation, or contraction (59/111, 53.2%), polyps or papillomatous/papillary lesions (39/111, 35.1%), sludge or stones (38/111, 34.2%), and dysplasia or carcinoma (7/111, 6.3%). Severe complications included recurrent gastrointestinal bleeding, massive hemobilia, and pediatric gallbladder carcinoma. Available data do not support restriction of gallbladder involvement to late-infantile or neurologically advanced MLD. Gallbladder abnormalities have been reported before neurological diagnosis, in presymptomatic candidates for gene therapy, and after disease-modifying treatment. Conclusions Gallbladder disease is a clinically meaningful systemic manifestation of MLD across the phenotypic spectrum. Comparison of the evidence synthesized in this review with existing American and European consensus recommendations supports baseline and longitudinal ultrasound assessment of the gallbladder, including before and after disease-modifying treatment. We propose a practical approach to surveillance and escalation of care that is intended to support clinical decision-making rather than serve as a formally validated guideline.