Pityriasis Alba

Albinism and Vitiligo. Albinism is caused by a congenital inability to synthesize melanin as a result of genetic defects in the biochemical pathway that manufactures melanin. Vitiligo is a result of melanin loss in patchy areas of the skin. It develops after birth and is progessive (brown pigment on legs is patient's normal skin color).

FIG. 6.23. Pityriasis rosea. A: Pityriasis rosea causes a papulosquamous eruption that frequently involves the thorax and assumes a characteristic "Christmas tree" appearance. B: The individual lesions are elongated maculopapules with a rough surface. They follow the skin lines, which leads to the branching pattern of the chest. C: Psoriasis, another papulosquamous eruption more often appears on the extensor surface and has a silvery scale.

Vitiligo at the wrist skin of the left hand in a 42-year-old man who had developed Vogt-Koyanagi-Harada syndrome 8 months before.

Area of depigmentation of skin surrounding the eye in a patient with vitiligo associated with severe iritis.

Closer view of area of skin depigmentation. Note associated whitening of lashes (poliosis).

actinic keratosis: numerous keratoses over te scalp induced by chronic ultra-voilet exposure

Segmental vitiligo: anterior trunk

tinea versicolor - hypopigmented (in this case) irregular macules on upper back

tinea versicolor - salmon-colored (in this case) irregular macules on chest. Also involved neck and upper back

Tinea Versicolor More common than vitiligo is this superficial fungus infection of the skin. It causes hypopigmented, slightly scaly macules on the trunk, neck, and upper arms. They are easier to see in darker skin and may become more obvious after tanning. In lighter skin, the macules may look reddish or tan instead of pale. The macules may be much more numerous than in this example.

FIGURE 21-10. Vitiligo. Depigmented macules appear on the skin and may merge into large areas that lack melanin. The brown pigment seen in the illustration is the person?s normal skin color; the pale areas are caused by vitiligo. (Reprinted with permission from Bickley LS. Bate's Guide to Physical Examination and History Taking. 8th Ed. Philadelphia: Lippincott Williams & Wilkins, 2003.)

Pityriasis rosea. Present for 2 weeks. A 4 cm lesion noted on breast. Ovoid, central "collarette" scale

Pityriasis alba: cheek, boy

Pityriasis rosea: anterior trunk, adult male

Actinic keratosis

Icthyosis vulgaris: "Dry" skin in a 6 year-old with eczema and pityriasis alba

Pityriasis alba in a teen with asthma and eczema. Note the xerosis.

Pityriasis alba in an African American teen with asthma

Pityriasis alba in a young woman with atopy

Pityriasis alba: Subtle hypopigmented macules and dry skin in a child with atopy

Actinic Keratosis Actinic keratoses are superficial, flattened papules covered by a dry scale. Often multiple, they may be round or irregular, and are pink, tan, or grayish. They appear on sun-exposed skin of older, fair-skinned persons. Though themselves benign, these lesions may give rise to squamous cell carcinoma (suggested by rapid growth, induration, redness at the base, and ulceration). Keratoses on face and hand, typical locations, are shown.