Extensive intramuscular venous malformation in the lower extremity.

Typical venous malformations are easily diagnosed by skin color changes, focal edema or pain. Venous malformation in the skeletal muscles, however, has the potential to be missed because their involved sites are invisible and the disease is rare. In addition, the symptoms of intramuscular venous malformation overlaps with myofascial pain syndrome or muscle strain. Most venous malformation cases have reported a focal lesion involved in one or adjacent muscles. In contrast, we have experienced a case of intramuscular venous malformation that involved a large number of muscles in a lower extremity extensively.