Varicella Chickenpox. Varicella Chickenpox is caused by a virus of the herpes group. The disease is highly contagious and is spread by droplet or direct contact. The incubation period for chickenpox ranges from 11 to 21 days. Prodromal symptoms consist of low-grade fever, headache, anorexia, and malaise. On the following day, the characteristic rash begins to appear. The lesions evolve from erythematous macules to form small papules. Quickly, a clear vesicle arises on this erythematous base. The classic lesion of chickenpox has been poetically described as a “dewdrop on a rose petal.” Over the next several days, the vesicles rupture and then crust. The rash begins on the chest and back and spreads centrifugally to involve the face, scalp, and the extremities. New lesions of chickenpox arise in crops over a period of several days.
Trachyonychia (twenty nail dystrophy of childhood). Any skin disease that affects the nail matrix may result in an abnormal nail plate. There are children, though, who only manifest dystrophy of the nail without any other cutaneous lesions, a condition that has been termed twenty nail dystrophy of childhood. The nails have a rough, sandpaper-like quality as well as longitudinal ridging and occasional splitting at the distal nail edge. Similar nail changes can be seen in lichen planus and alopecia areata. In many patients the condition spontaneously regresses.
Xerosis. The accentuation of skin markings and fine scale illustrated here are typical of xerosis. The tendency toward dry skin tends to be inherited and is more common in families with a history of atopy. Low humidity, usually related to dry heat during the winter months, is an aggravating factor. Treatment of xerosis is aimed at rehydrating the stratum corneum. Emollients containing urea or alpha-hydroxy acids are particularly effective. Excessive bathing and the use of alkaline soaps must be avoided.