Differential diagnosis — Capillary malformation

First of all, isolated cutaneous capillary malformations (CM) must be distinguished from the special types, nevus simplex, cutis marmorata telangiectatica congenita (CMTC) and teleangiectasias.

The most common and, from the therapeutic point of view, highly relevant differential diagnosis is infantile hemangioma, which can also show a segmental configuration as a variant in the cervicofacial region and on the extremities (e.g. PHACES syndrome). Classic distinguishing features of infantile hemangiomas and capillary malformations are summarized in the following table.

Capillary malformations may be partial manifestations of complex clinical conditions. Despite great clinical variability, further imaging examinations should be considered in the case of the following clinical signs:

• Areal capillary malformations in the upper half of the face with midline border (Sturge-Weber syndrome)
• Capillary malformations in the lumbar region (spinal dysraphism, Cobb syndrome, lumbar/sacral syndrome)
• Hyperthermic “capillary malformations” with or without auscultatory thrill (AVM)
• Capillary malformations and pathologically increased or decreased head circumference (MCAP, MICCAP)
• Capillary malformations associated with disproportional overgrowth (e.g., CLOVES or Klippel-Trénaunay syndrome)
• Dilated, irregular vessels in the area of the capillary malformation (e.g., CVM)
• Extensive capillary malformation laterally on the leg (combined CVM, Klippel-Trénaunay syndrome)

Although rare at birth and in early infancy, linear circumscribed scleroderma (morphea) should be considered as an important differential diagnosis for capillary malformations in the face and neck region of newborns. After initially appearing as a linear red patch of facial skin, the skin in morphea shows hardening and atrophy as it progresses. Thus a biopsy followed by histopathologic tissue examination should be performed early if these symptoms appear.

Cutaneous AVM is also occasionally visible as reddish, patchy discoloration of the skin. However, it is usually more indistinctly demarcated and shows clinically (hyperthermia) and sonographically (especially in color-coded duplex sonography) marked hyperperfusion, often including dilated subcutaneous vessels.

Cutis marmorata telangiectatica congenita (CMTC) has a more reticular configuration and consists of a reddish, marbled pattern with intervening normal areas of skin. It may also be combined with capillary malformation.

Nevus simplex occurs in at least one-fifth of all newborns, mostly in the nuchal region (“stork bite”), on the eyelids and mid-forehead region, or between the eyebrows. Compared to a capillary malformation,  nevus simplex is light or salmon red and often has blurred margins to the surrounding skin.