Table of Content


Spring 2016, Vol. 24 No. 1

Hong Kong J. Dermatol. Venereol. (2016) 24, 59

Answers to Dermato-venereological Quiz

Answers to Dermato-venereological Quiz

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  1. Diascopy, Wood's lamp examination, and application of friction by stroking the lesion and the surrounding skin. There was prominent erythema surrounding the lesion, which was blanchable upon diascopy and pressure application (Figures 2 & 3). Wood's light examination showed no accentuation. Stroking the lesion does not produce reactive erythema. All these tests help to reveal that the appearance of the lesion is not due to a decrease in pigmentation but is caused by a reduction in vascular perfusion.
  2. The differential diagnoses include: (a) Naevus anaemicus, (b) Naevus depigmentosus, (c) Vitiligo. The most likely diagnosis is naevus anaemicus. Naevus anaemicus is a congenital vascular anomaly that usually presents at birth. It usually presents as a hypopigmented macule or patch. It is an uncommon condition first described by Vorner in 1906. The relative hypopigmented appearance is actually due to vasoconstriction causing hypoperfusion of the skin. This is due to a localised "nevoid lesion" with hypersensitivity to catecholamines causing vasoconstriction.1 It has been proposed by some that an abnormality in endothelial adhesion molecule induction (E-selectin expression) may be involved. The lesion tends to remain unchanged throughout life and grows with the child. It is asymptomatic and there may be a female predilection. The lesions may occur in patients with neurofibromatosis. There may also be an association with capillary malformations such as port-wine stain, which could be the phenomenon of twin-spotting. Naevus anaemicus has also been described in patients with phakomatosis pigmentovascularis.
  3. The diagnosis is clinical. No histological abnormality can be identified. A detailed clinical examination to identify other associations is usually sufficient.
  4. Apart from cosmetic concerns, no treatment is required although camouflage make-up may be considered.
Figure 2

Figure 3


1. Greaves MW, Birkett D, Johnson C. Nevus anemicus: a unique catecholamine-dependent nevus. Arch Dermatol 1970;102:172-6.