Capillary lymphatic venous malformations (CLVMs) are rare blood vessel abnormalities that involve capillaries, veins, and lymphatic vessels. Patients with CLVMs have a capillary malformation, also called a port wine birthmark, that is next to or covers the abnormal veins and lymphatic vessels. CLVMs have a variety of looks and complications. Patients with these malformations may have a variety of soft tissue and bone growth problems such as different lengths or girths of the legs or arms, enlarged fingers or toes, and scoliosis (abnormal curvature of the spine/back).
Capillary lymphatic venous malformations form prior to birth. They are not caused by any exposures during pregnancy. Most CLVMs are identified at birth or in early childhood.
Capillary lymphatic venous malformations also includes two syndromes: Klippel-Trénaunay syndrome (KTS) and CLOVES syndrome. Individuals with KTS have soft tissue and/or bone enlargement of the extremity affected by the CLVM; not all patients with KTS have abnormal lymphatic vessels. The acronym CLOVES stands for: congenital lipomatous overgrowth, vascular malformations, epidermal nevi, scoliosis / skeletal and spinal abnormalities. Individuals with CLOVES syndrome may also have an arteriovenous malformation (AVM) in addition to a CLVM.
Some individuals with CLVM have been found to have a mutation of the PIK3CA gene in the overgrown tissue. This mutation is not inherited and is only found in the affected tissue(s).