A rare multisystem congenital disease, part of the complex lymphatic anomalies (CLA). There is some overlap with Kaposiform lymphangiomatosis (KLA). GLA is characterized by diffuse proliferation of lymphatic channels in osseous and extraosseous tissues. The pathogenesis includes somatic pathogenic variants in RAS/PI3K/mTOR signaling pathway. Patients with GLA have bone and visceral involvement, but in contrast with Gorham Stout Disease, cortical bone is not affected.