Section 24. Miscellaneous Pigmentary Disorders

This condition is characterized by whorled areas of hypopigmentation following lines of Blaschko that are present from birth or evolve during early childhood. The lesions may be generalized, with individual areas of hypopigmentation assuming whorled or streaked patterns. A very small number of patients with this pigmentary disorder have central nervous system disease, usually manifest as seizures or mental retardation. Other reported abnormalities include skeletal and ocular defects. This condition was formerly called hypomelanosis of Ito.

This is a congenital condition characterized by hyperpigmentation that follows lines of Blaschko in a linear pattern on the extremities and a whorled pattern on the trunk. The hyperpigmentation may be present at birth or develops shortly thereafter, spreading during the first 2 years of life, at which time it stabilizes.

These are localized areas of hypopigmentation that are usually present at birth. The lesions may be irregular in size and shape and occasionally follow a linear or segmental pattern. Electron microscopic study of these areas suggests that melanosomes are not being transferred from melanocytes into surrounding keratinocytes. There are no associated abnormalities.

This circumscribed area of macular hypopigmentation is due to a localized vascular abnormality. Chest and back are the most common locations. In contrast to nevus depigmentosus, erythema does not develop in response to stroking or the application of ice or warm water. Hypersensitivity of the involved vessels to catecholamines has been postulated as a cause.

The vegetable pigment carotene is widely distributed in carrots, lettuce, squash, and many other vegetables and fruits. A diet that is very rich in these foods results in a yellowish-orange discoloration of the skin. This appearance is usually localized to the palms and soles (note the hand on the left) but may also involve the skin of the face. The presence of normal sclerae distinguishes the clinical appearance of this condition from that of jaundice. Return to normal skin color follows a reduction in dietary intake of carotene.

This genetic disorder is transmitted as an autosomal dominant, with variable penetrance. It is characterized grossly by partial albinism in the form of a white forelock (Fig. 24-7), broad nasal root (Figs. 24-7 and 24-8), hypertrichosis of the inner portions of the eyebrows, lateral displacement of the medial canthi (Figs. 24-7 and 24-8...