Background: Lymphatic endothelial cells (LECs) derived from lymphatic malformations (LMs) bear activated PIK3CA alleles yet display an inflammatory gene expression profile. A basis for the inflammatory phenotype was sought by screening for coexisting somatic mutations. Methods and Results: Fourteen independent LEC populations bearing activated PIK3CA alleles were isolated from LM. These were characterized by the expression of growth and inflammatory genes (VEGFC, IL-6, COX-2, IL-8, HO-1, E-SEL) by qRT-PCR. Most commonly upregulated gene products were VEGFC, COX2, HO-1, and ANGPTL4. The specific inhibition of PI3K reduced VEGFC expression without resolving inflammation. Whole exome sequencing of six LM-LEC populations identified five novel somatically acquired alleles coexisting with activated PIK3CA alleles. Two affected genes regulate lipid droplet metabolism (FITM2 and ATG2A), two are gene regulators (MTA1 and TAF1L), and the fifth is an isoform of ANK3 (an endosomal/lysosomal protein). Inhibition of AMPK implicated its involvement in regulating COX-2 and HO-1 overexpression. ANGPTL4 expression was independent of AMPK and PI3K activity and reflected lipid stress demonstrated in normal LECs. AMPK activation with AICAR had a selective growth-limiting effect in a subset of LM-LEC isolates. Conclusions: Inflammatory stress displayed by LM-LECs is consistent with errors in lipid metabolism that may be linked to acquired mutations. The acquisition of PIK3CA alleles may be a permissive event that antagonizes inflammation and metabolic defect.

Introduction: Cloaca malformation repair strategy is strongly dictated by common channel and urethral lengths. Mid to long common channel cloacas are challenging and often require laparotomy for dissection of pelvic structures. The balance of common channel and urethral lengths often dictates the approach for reconstruction. Laparoscopy has been utilized for rectal dissection but not for management of the urogenital (UG) structures. We hypothesized that laparoscopy could be applied to UG separation in reconstruction of cloaca malformations. Methods: Records were reviewed for 9 children with cloaca who underwent laparoscopic rectal mobilization and UG separation. Clinical parameters reviewed included demographics, relevant anatomic lengths, operative duration, transfusion requirements, and perioperative complications. Results: Repair was perfomed at a median (interquartile range) age of 12 (7, 15) months. Common channel length as measured by cystoscopy was 3.5 (3.3, 4.5) cm. There were no intraoperative complications. Transfusion requirements were minimal. Postoperative length of stay was 6 (5, 11) days. One patient developed a urethral web and 2 developed vaginal stenosis. One patient later underwent a laparotomy for obstruction due to a twisted rectal pull-through. Conclusions: Laparoscopic rectal mobilization and UG separation in long common channel cloaca are safe and well tolerated. Laparoscopy affords full evaluation of Mullerian structures and enables separation of the common UG wall, which may ultimately enhance long-term urinary continence.