Nevus anemicus is a congenital vascular anomaly that presents clinically as a hypopigmented macule or patch, as shown below. The lesional pallor is due to a localized hypersensitivity to catecholamines with resultant vasoconstriction. Nevus anemicus is an uncommon disorder and was first described by Vorner in 1906.
 View Image | Irregularly shaped, well-demarcated, asymptomatic hypopigmented patch of nevus anemicus on the lateral leg. |
Intralesional injection of bradykinin, acetylcholine, serotonin, nicotine, 5-hydroxytryptamine, and histamine fails to induce the anticipated vasodilatation or erythema in the affected area. However, erythema does follow an axillary sympathetic block of the involved limb or intradermal injection of the alpha-adrenergic blocking agent, pilocarpine. These findings suggest that nevus anemicus is best termed a pharmacologic nevus resulting from increased vascular sensitivity to catecholamines.[1] This conclusion is further supported by autograft exchange transplantation studies that show donor site dominance. It also has been proposed that an abnormality in endothelial adhesion molecule induction (E selectin expression) may be involved, suggesting several pharmacologic anomalies are involved and further supporting the idea that nevus anemicus may best be termed a pharmacologic nevus.
Nevus anemicus is due to a congenital anomaly of the cutaneous vasculature resulting in hypersensitivity to catecholamines, leading to localized vasoconstriction.
The prevalence of nevus anemicus in several research control groups was documented at 1-2%.[2]
No racial predilection has been noted in the literature for nevus anemicus.
Early literature reports nevus anemicus occurring more frequently in females. Review of the literature of nevus anemicus occurring in the setting of neurofibromatosis type 1 describes equal frequency in females and males.[3]
Nevus anemicus may be present at birth or first appreciated in early childhood.
The prognosis of nevus anemicus is excellent. Lesions of nevus anemicus usually persist unchanged throughout life. They are asymptomatic. However, nevus anemicus presenting in a child with multiple café-au-lait macules should raise concern for neurofibromatosis type 1. Two prospective studies document about a 50% prevalence of nevus anemicus in neurofibromatosis type 1.[3, 2]
Patients with nevus anemicus typically present with an asymptomatic pale macule or patch that has been present since birth and grows with the child. Frequently, the lesion of nevus anemicus is noted as an incidental finding on skin examination.
Clinically, nevus anemicus is a circumscribed, rounded, oval or linear pale macule or patch with irregular margins that may be surrounded by satellite macules. Lesions may be single or multiple and may be located on any part of the body, but most lesions commonly are found on the upper chest. Lesions typically are asymptomatic. Nevus anemicus is noted at birth or in early childhood, although it may be easily overlooked. Stroking or rubbing of the surrounding skin can make subtle lesions more apparent.
Nevus anemicus usually persists unchanged throughout life. Lesions occur with increased frequency in patients with neurofibromatosis.[2, 4] Areas of nevus anemicus frequently are extensive and have been observed in close association with capillary malformations of port-wine stain type, a phenomenon attributed to somatic recombination. Nevus vascularis mixtus or mixed vascular nevus describes the co-occurrence of nevus anemicus and vascular malformations of the reticular telangiectatic type; association with brain abnormalities of the Dyke-Davidoff-Masson type has been reported.[5] Nevus anemicus also has been described in patients with phakomatosis pigmentovascularis, a syndrome characterized by vascular and melanocytic nevi.[6, 7] Phakomatosis pigmentovascularis type IIa has been associated with primary choroidal melanoma.[8]
Nevus anemicus can be distinguished from various segmental hypomelanoses, such as vitiligo and hypochromic nevi, by diascopy (ie, by applying pressure with a glass slide to the lesion and adjacent unaffected skin). With diascopy, nevus anemicus becomes indistinguishable from the surrounding skin, which is now blanched from the pressure of the slide. Loss of melanin does not occur in the lesion. Wood lamp examination does not accentuate nevus anemicus and may make the lesion inapparent, unlike true depigmenting disorders. The application of friction, cold, or heat does not produce changes within the lesion. Thus, scratching a line across both the lesion and normal surrounding skin will produce erythema in the normal skin but not within the lesion.
The histology of nevus anemicus is normal, and melanocytes are preserved and normally distributed. Electron microscopy fails to detect abnormalities in the vascular structure.
Treatment generally is not required for nevus anemicus. Patients troubled by the cosmetic appearance of the nevus anemicus lesion may benefit from the application of camouflage makeup.
Irregularly shaped, well-demarcated, asymptomatic hypopigmented patch of nevus anemicus on the lateral leg.
Irregularly shaped, well-demarcated, asymptomatic hypopigmented patch of nevus anemicus on the lateral leg.
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