Slow-flow malformation, venous type

Slow-flow malformation, venous type (also known as venous malformation or VM) is a congenital vascular anomaly characterized by abnormally formed veins that create dilated, sponge-like channels filled with slow-moving blood. These malformations are present at birth, although they may not become clinically apparent until later in life. They can occur anywhere in the body but most commonly affect the skin, subcutaneous tissues, muscles, and mucous membranes (such as the oral cavity). Venous malformations tend to grow proportionally with the individual and may expand over time, particularly during puberty, pregnancy, or following trauma. Key clinical features include soft, compressible, blue-purple masses that swell with dependent positioning or Valsalva maneuver. Patients may experience pain, swelling, and functional impairment depending on the location and size of the malformation. Localized intravascular coagulopathy (LIC) is a common complication, characterized by elevated D-dimer levels and low fibrinogen, which can occasionally progress to disseminated intravascular coagulation (DIC). Phleboliths (calcified thrombi) are frequently found within the lesion and are a hallmark radiographic finding. Joint involvement can lead to arthropathy and limited range of motion. Most venous malformations occur sporadically, though familial forms exist, including those associated with somatic or germline mutations in the TEK (TIE2) gene or PIK3CA gene. Treatment is multidisciplinary and may include compression garments, low-molecular-weight heparin for coagulopathy management, sclerotherapy (injection of sclerosing agents to shrink the malformation), surgical resection, and in some cases sirolimus (an mTOR inhibitor) for extensive or symptomatic lesions. Complete cure is often difficult to achieve, and management focuses on symptom control and prevention of complications. Diagnosis is typically confirmed through MRI, which shows characteristic T2-hyperintense lesions with slow flow.

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