Complex Lymphatic Anomalies (CLA) comprise a group of related rare lymphatic disorders: generalized lymphatic anomaly (GLA), Gorham-Stout disease (GSD), kaposiform lymphangiomatosis (KLA), and central conducting lymphatic anomaly (CCLA).

CLA is an umbrella term developed through a consensus of members of the International Society for the Study of Vascular Anomalies (ISSVA) to describe a group of disorders that continue to be reported in the medical literature by more than a dozen names. What was commonly referred to as lymphangiomatosis when the LGDA was formed is now generalized lymphatic anomaly (GLA). Central conducting lymphatic anomaly was previously called lymphangiectasia. Other disease names that are now considered to belong under the CLA umbrella are cystic angiomatosis, vanishing bone disease, Diffuse Pulmonary Lymphangiomatosis, and many more.

Patients with any of the four types of CLA commonly experience the abnormal development of the lymphatic system, manifesting in serious medical complications. This includes destruction of bone leading to disfigurement and pain, life-threatening collections of fluid around the heart and lungs, progressive loss of lung function, severe infections, and abnormal blood clotting. Treatment is aimed at slowing the underlying abnormal lymph vessel overgrowth with medication and addressing the many resulting complications with medication and surgical procedures.

One of the primary goals of the LGDA Patient Registry is to put the power of patient reported data to work to accelerate research to help advance understanding of the causes and develop effective treatments for all patients with a CLA.