Striae Distensae

7/11/2009 · Kategori: Dermatology

Striae Distensae

Author: Samer Alaiti, MD, FACP, Clinical Assistant Professor, Departments of Dermatology and Internal Medicine, University of California at Los Angeles School of Medicine; Medical Director, Miracle Mile Medical Center for Dermatology and Cosmetic Surgery, Inc

Introduction

Background

Striae distensae, a common skin condition, do not cause any significant medical problem; however, striae can be of significant distress to those affected. They represent linear dermal scars accompanied by epidermal atrophy.

Pathophysiology

Striae distensae affect skin that is subjected to continuous and progressive stretching; increased stress is placed on the connective tissue due to increased size of the various parts of the body. It occurs on the abdomen and the breasts of pregnant women, on the shoulders of body builders, in adolescents undergoing their growth spurt, and in individuals who are overweight.

Skin distension apparently leads to excessive mast cell degranulation with subsequent damage of collagen and elastin. Prolonged use of oral or topical corticosteroids or Cushing syndrome (increased adrenal cortical activity) leads to the development of striae. Genetic factors could certainly play a role, although this is not fully understood.

Frequency

United States

Approximately 90% of pregnant women, 70% of adolescent females, and 40% of adolescent males (many of whom participate in sports) have stretch marks.

International

International figures may reasonably mirror the numbers in the United States.

Mortality/Morbidity

Striae distensae are usually a cosmetic problem; however, if extensive, they may tear and ulcerate when an accident or excessive stretching occurs.

Race

Stretch marks affect persons of all races.

Sex

Striae affect women more commonly than men.

Age

Stretch marks affect adolescents, pregnant women, and patients with excessive adrenal cortical activity.

Clinical

Physical

Early striae present as flattened, thinned skin with a pink hue that may occasionally be pruritic. Gradually, they enlarge in length and width and become reddish purple in appearance (striae rubra). The surface of striae may be finely wrinkled. Mature striae are white, depressed, irregularly shaped bands, with their long axis parallel to the lines of skin tension. They are generally several centimeters long and 1-10 mm wide. Gradually, some striae may fade and become inconspicuous. The natural evolution of stretch marks is similar to that of scar formation or a healing wound.

• In pregnancy, striae usually affect the abdomen and the breasts.
• The most common sites for striae on adolescents are the outer aspects of the thighs and the lumbosacral region in boys and the thighs, the buttocks, and the breasts in girls. Considerable variation occurs, and other sites, including the outer aspects of the upper arms, are occasionally affected.
• Striae induced by prolonged systemic steroid use are usually larger and wider than other phenotypes of striae, and they involve widespread areas, occasionally including the face.
• Striae secondary to topical steroid use are usually related to enhanced potency of the steroids when using occlusive plastic wraps. They usually affect the flexures and may become less visible if the offending treatment is withheld early enough.

Causes

• The factors that lead to the development of striae are poorly understood. No general consensus exists as to what causes striae. One suggestion is that they develop as a result of stress rupture of the connective tissue framework. It has also been suggested that they develop more easily in skin that has a high proportion of rigid cross-linked collagen, as occurs in early adult life. This is evident in striae due to pregnancy, lactation, weight lifting, and other stressful activities. Increased adrenal cortical activity has been implicated in the formation of striae, as in the case of Cushing syndrome. Additionally, the cellular and extracellular matrix alterations that mediate the clinical phenotype of stretch marks remain poorly understood.