14800-DvRappard

153 Gallbladder and the risk of polyps and carcinoma in metachromatic leukodystrophy 9 In 3 patients (MLD-2, MLD-37 and MLD-38) in whom ultrasound showed a thickened gallbladder wall, histology showed prominent Rokitansky-Aschoff sinuses with fibrosis and hyperplasia of the muscle wall. Prominent Rokitansky-Aschoff sinuses without hyperplasia of the muscle wall were also detected in 3 patients (MLD-46, MLD-60, MLD- 63), in whom no wall thickening was detected at ultrasound. Besides cholelithiasis and scattered macrophages filled with storage material, histopathology of the patient with recurrent pancreatitis (MLD-41) showed normal findings. The stroma of the polyps and mucosa of the wall contained foamy macrophages with periodic-acid-Schiff-positive metachromatic material (2 L and M). Of note, presence and extent of sulfatide storage differed between HSCT-treated and untreated patients. The number of macrophages containing sulfatides was considerably higher in untreated patients, including those who underwent cholecystectomy before transplantation, whereas little (MLD-2, MLD-41 and MLD-37) or no storage material (MLD-46) was detected in HSCT-treated patients. There was no difference in incidence of other abnormalities between HSCT-treated and untreated patients. DISCUSSION In this first systematic evaluationof gallbladder involvement inMLD, we found significant abnormalities in a high percentage of patients (26/34, 76%). Gallbladder sludge was frequent, regardless of transplantation status. Although HSCT is a known predisposing factor for its formation, 19,20 this typically occurs within the first 6 months after HSCT, while most of our patients were at least 1 year post HSCT. Furthermore, the conditioning regimens (hypothesized to impair gallbladder contractility resulting in sludge) used for MLD patients are not as intensive as those used for most hematological conditions. We therefore assume that MLD itself and not HSCT causes sludge. In one quarter, polypswere foundby ultrasound, considerablymore often than expected inapopulationofhealthychildrenandyoungadults.Thetrueprevalenceofpolyps inMLD is likely even higher, since in 2 patients polyps were detected only at histopathological examination while ultrasound only showed a thickened gallbladder wall. At histopathological examination, these polyps were all hyperplastic. In addition, intestinal metaplasia and hyperplasia of the gallbladder mucosa were present in 8 of 12 cases. The exact prevalence of gallbladder polyps in children is unknown, but considered as extremely rare. 21 In healthy adults, irrespective of age, prevalence of gallbladder polyps varies between 3 and 7% at ultrasound, cholesterol polyps being by far the most frequent type at histologic examination. 22, 23 Gallbladder polyps are usually