The upper arms and forearms have two contrasting aspects—the sun-exposed extensor surface and the sun-protected flexor surface. Different conditions affect each side. Predictably, the sun-exposed extensor arm is subject to sun damage (dermatoheliosis), photo eruptions, actinic keratoses, squamous cell carcinomas, keratoacanthomas, solar lentigines, and melanoma.

The inner, sun-protected flexural areas of the arms and legs, the antecubital and popliteal fossae, common settings for atopic dermatitis, are discussed together here. The extensor elbows and knees are primary sites for psoriasis, and the extensor legs are frequently places for lichen planus and scabies to appear.


Keratosis Pilaris

Distinguishing Features

  • Tiny, rough, red, or tan spiny follicular papules distributed in a grid-like pattern on the deltoid areas (Fig. 13-1)

  • “Goose flesh,” “sandpaper-like” texture when palpated

Follicular Eczema

Distinguishing Features

  • Characterized by the appearance of small, rough, erythematous papules in a grid-like pattern, often with crusting and marked pruritus

Pityriasis Alba

Pityriasis alba is a common skin condition affecting children and adolescents aged 3 to 16 years. The hypopigmented spots are mostly seen on the face in children who have atopic dermatitis (see also Cheeks). As with follicular eczema, described above, pityriasis alba is most often noted in children of color.

Distinguishing Features

  • Asymptomatic

  • Lesions most often appear on the lateral upper arms (Fig. 13-3) as well as the cheeks (see Fig. 7-6)

  • Present as one or more round, oval, or irregular whitish patches or thin plaques, with or without fine surface scale

  • Often appears following sun exposure because tanning of surrounding skin unmasks affected areas

  • Resolves spontaneously

Acne Vulgaris

Distinguishing Features

  • Inflammatory acneiform lesions, papules, and pustules (Fig. 13-4)


Localized Plaque Psoriasis

Distinguishing Features

  • Lesions may vary from well-demarcated, whitish or silvery erythematous plaques on the elbows (Figs. 13-5 and 13-6) and knees

  • Plaques can be very thick and hyperkeratotic

  • Usually not pruritic

  • Generally symmetric in distribution

Jan 8, 2023 | Posted by in Dermatology | Comments Off on Arms

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