Angiokeratoma circumscriptum. This vascular ectasia may be present at birth but has been reported to develop in childhood and even adulthood. There is a higher incidence in females. Lesions are most commonly found on the lower extremities but may be found elsewhere. Lesions consist of small nodules or larger plaques characterized by a dark red to purple color and a warty, hyperkeratotic scale sometimes in a linear distribution. These lesions may bleed when traumatized.
Erythema infectiosum (fifth disease). Erythema infectiosum is a mild childhood disease that is caused by human parvovirus B19. This condition develops after a mean incubation period of 14 days. There are few if any prodromal symptoms. The rash evolves in three clinical stages. The first stage is characterized by the abrupt appearance of a bright-red malar blush. The appearance is so startling that it has been given the suggestive description of “slapped cheeks”. During the second stage, the facial rash begins to fade, and a maculopapular, urticarial, or morbilliform exanthem develops on the extremities and trunk. Pruritus may be present.
Allergic contact dermatitis (reaction to temporary tattoo). Contact allergy to temporary tattoos has become an increasingly common phenomenon. In most cases, the tattoo material does not contain pure henna, but is a mixture of brown henna with paraphenylenediamine (PPD) called black henna. The patient is allergic to PPD in the tatto. In fact, the concentration of PPD in black henna is higher than that seen in commercial hair dyes. After resolution of the eczematous skin eruption, postinflammatory hyperpigmentation may persist for a considerable period of time.
Twin-to-twin “transfusion”. Twins who develop with some form of common circulation in utero may show a temporary difference of cutaneous color related to oddities of hemodynamics. In the figure, one sees twin neonates, of whom the one on the right is uniformly and abnormally erythematous, whereas the other is abnormally pallid. The one looks plethoric, the other, anemic. In the course of time, restoration of normal blood counts and color will develop in both.