Lymphatic anomalies are a rare subset of vascular anomalies that are poorly understood. the understanding of the natural history, long-term outcomes, risk factors for morbidity and mortality, and the relative benefit of medical therapies and procedures is limited.The goal of this project is to better understand these diseases and improve the care of theses rare patients. To do this, the investigators are conducting an observational study of patients with lymphatic anomalies, including an annual follow-up questionnaire to gather prospective data on mortality, morbidity, treatments, and functionality as well as quality of life.

The purpose of the Lymphatic Anomalies Registry, created at Boston Children's Hospital, is to create a database to help current and future patients diagnosed with a lymphatic anomaly. The ultimate goal of the registry is to better understand and predict responses to therapies and risk factors for complications. Although the Lymphatic Anomalies Registry exists at Boston Children's Hospital, patients can be entered into the registry regardless of whether or not they visit Boston Children's Hospital, thus increasing the program's accessibility. The Lymphatic Anomalies Registry includes patients who have vascular anomalies with a lymphatic component across various diagnoses. From the patient's perspective, participation in the Lymphatic Anomalies Registry means taking part in a short, thirty minute interview, and providing the registry with access to medical records. The interview is conducted verbally with study staff of the Lymphatic Anomalies Registry, and can take place either at the hospital, or over the phone. During the interview, the registry will inquire about the patient's diagnosis, disease features, medical therapies, and procedures. Interested prospective patients will receive an introductory packet from the registry with information on how to proceed in the registry process. All obtained patient information is housed on a secure, HIPPA compliant, internal database, managed by Boston Children's Hospital staff. Patient information entered into the external database is de-identified. The research teams will also obtain a medical record release form to request the patient's medical record for review in our study.

Inclusion Criteria:

• Clinical diagnosis of complex vascular tumor, malformation or overgrowth syndrome with significant lymphatic component

Both domestic and international patients with complex lymphatic anomalies, as described above, are eligible to participate. Travel to Boston is not required for participation. Eligible patients are identified through active referral in the Vascular Anomalies Center at Boston Children's Hospital. Physicians and patients may also refer eligible patients directly to the Lymphatic Anomalies Registry. Patients may indicate interest in participation themselves by contacting the registry team through the "Contact Us" link on www.lymphaticregistry.org.