Characteristics of the clinical presentation — Capillary malformation

Characteristic features of capillary malformations (CM) are:

• the sporadic (non-familial) occurrence of simple CMs
• the variable expression of their color, size and shape
• the characteristic structure of dermal capillaries
• relatively frequent association with growth disorders and syndromes
• possible co-occurrence with venous and/or lymphatic vascular anomalies.

Isolated capillary malformations are quite common and are rarely associated with complications. Although comprehensive, epidemiologic studies are not available, it can be assumed that capillary malformations manifest in approximately 0.2% to 0.3% of all newborns. Boys and girls, as well as mature and premature infants, each appear to be affected with equal frequency. As children grow up, the lesion often become less visible (“fading”) or sometimes changes color (lighter, but also darker, rarely changing toward blue).

Capillary malformations, like numerous other vascular malformations, seem to be caused by postzygotic mutations, leading to characteristic skin lesions in a configuration that is highly variable from patient to patient. They may appear as red patches unifocally or multifocally, small or large in area, and are sometimes oriented along embryonic developmental lines or are oriented to the midline. They are located at the level of the skin, most commonly in the face and neck region. In rare cases they may also be associated with very slowly increasing soft tissue proliferations in adulthood when located in the face.

Microscopic examination of clinically visible skin lesions reveals mainly dilatation of roundish to oval capillaries in the superficial and middle dermis of affected patients. These capillary malformations are lined by a thin layer of endothelial cells and lack smooth muscle cells. As they progress, they show increasing fibrosis and, if severe, may appear as nodular collections in deeper layers of the dermis as well as the subcutis, leading to a thickening and irregular contour of the skin surface described as cobblestone-like.

Capillary malformations can be associated with other, superficial or more deep-lying vascular malformations (see table) and then are frequently accompanied by growth disorders (overgrowth syndromes).

An occasional association of capillary malformations with neurologic abnormalities occurs in Sturge-Weber syndrome (SWS), microcephaly-capillary malformations (MICCAP), and megalencephaly-capillary malformations (MCAP).