Characteristics are the combination of diffuse capillary malformations and non-progressive, relatively benign regional overgrowth, normally as hemihyperplasia of an extremity. There is no relationship between localization and intensity of vascular changes. Clinically often referred to by the abbreviation: DCMO (diffuse capillary malformation with overgrowth).
DCMO occurs sporadically (not familial). Recently, a somatic (present only in affected tissue) autosomal dominant gain-of-function mutation (c.547C>T, p.Arg183Cys) in the GNA11 gene, which encodes a guanine nucleotide-binding protein (G protein), was detected in three patients.
Regional overgrowth (soft tissue-related) is not very severe, develops proportionally with body growth, and usually affects asymmetrically only one extremity. An entire half of the body including the face (hemihyperplasia) or one upper and one lower extremity (ipsilateral or crossed) may also be affected. Major vascular malformations are not part of DCMO.
Capillary malformations (CM) are characterized by a mesh-like reticular pattern and are diffusely distributed. Diffuse distribution is defined as a pattern that extends 2 to 3 cm beyond the midline of a specific body region. These body regions are considered to be the head/neck, right or left upper limb region (including arm, shoulder, and lateral chest/upper back); right or left thoracic half; right or left abdominal half; right or left side of back; right or left lower limb region (including leg, buttock, perineal region/suprapubic region, lower abdomen).
In a proportion of patients (approximately 30%), finger or toe anomalies are also present (cutaneous syndactyly, macrodactyly, sandal gap). In the case of hemifacial overgrowth, asymmetric dentition (accelerated on the affected side) is often observed.