ICD-9-CM 759.6 DiseasesDB 33714 | OMIM 608355 | |
Parkes Weber Syndrome (PWS) is an uncommon congenital vascular malformation (CVM) similar to Klippel–Trénaunay syndrome, but has its own distinct conditions. It was first described in 1907 by British dermatologist Frederick Parkes Weber. It is only found in about 0.3% of the world population.
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Characteristics
PWS is characterized by the venous malformations, cutaneous capillary malformations, and lymphatic malformations found in Klippel–Trénaunay–Weber syndrome along with arteriovenous malformation. It also can include fistulas occurring with skeletal or soft tissue hypertrophy. The syndrome can affect multiple limbs, the trunk, and the head. The body’s lower extremities are most commonly affected.
Capillary malformations
The most common effect of PWS is capillary malformations which are known as "port-wine stains". They first appears as a red macular stain of the skin that darkens over the years. Capillary malformations are flat, cutaneous, slow-flowing lesions that are made of venous channels that are dilated or are increased in number.
Vascular anomalies
Both arteriovenous malformations (AVM) and arteriovenous fistulas (AVF) are fast-flowing vascular anomalies. They can be in the skin, muscle, bone, internal organs, and brain. AVMs and AVFs can cause bleeding, congestive heart failure, or neurological consequences. AVFs specifically cause the high output cardiac failure. AVMs originate while going through embryogenesis and they are rarely found to regress spontaneously. These complications can make PWS a life-threatening condition.
Cause
Mutations on the RASA1 (RAS p21 protein activator 1) gene located on chromosome 5 cause Parkes Weber Syndrome. In normal circumstances, this gene mediates cellular growth, differentiation, and proliferation from various receptor tyrosine kinases on cell surfaces. Vascular anomalies are associated with this gene losing its function.
The gene is spread through inheritance. Recently patterns of autosomal dominance have been reported, which means the gene only needs to be from one parent in order to be passed on. PWS affects both males and females equally and no racial predominance has been found.