Skin Atrophy Striae

Skin atrophy striae, also known as stretch marks, are soft striae caused by skin expansion and associated with the weakening of elastic fibers in the skin. They are often seen in individuals who experience rapid weight gain during pregnancy or adolescence. Other causes include long-term use of potent topical corticosteroids, Cushing's syndrome, endocrine abnormalities, and connective tissue diseases.

I. Etiology and Pathogenesis

The local skin elastic fibers of patients are weakened due to endocrine influences. Pregnant women and adolescents have increased adrenal cortex secretion, and diseases like Cushing's syndrome cause adrenal cortex hyperfunction, secreting large amounts of glucocorticoids. Long-term use of steroids also results in high levels of glucocorticoids in the body, which break down some fibrin into sugar, weakening the connective tissue and especially the elastic fibers in the skin. The elastic fibers and collagen fibers in the skin become degenerated and significantly thinner. Therefore, when the abdominal wall of a woman rapidly expands due to pregnancy, or a youth grows rapidly in height or weight, or the breasts enlarge quickly due to lactation, the subcutaneous fat increases significantly in a short period for patients with Cushing's syndrome or long-term steroid use. The elastic fibers lose their function when the skin is overstretched, resulting in striae that do not return to their original state.

II. Clinical Manifestations

Initially, the disease presents as linear red or purplish-red patches, with faintly visible subcutaneous blood vessels. Upon pressure, the patches wrinkle, also known as striae rubrae. Over time, the lesions gradually turn pale yellowish-white or normal skin color, resembling atrophic linear scars that persist permanently without subjective symptoms. They commonly occur near the knees of rapidly growing or obese adolescents, the inner upper arms, the inner thighs, and the lumbar and dorsal regions. In lactating women, they can appear on the breasts and are most commonly seen on the abdominal wall of pregnant women, referred to as pregnancy striae. For individuals with adrenal cortex hyperfunction or long-term oral corticosteroid use, they frequently occur on the inner upper arms and inner thighs.

III. Pathological Features

The histological changes of this disease include epidermal atrophy, swelling of the reticular dermis fibers, collagen fiber degeneration, thinning of the elastic fibers, and a lighter stain of elastic fibers. In chronic lesions, the central area almost completely lacks elastic fibers, with only some curled fine elastic fibers at the edges.

IV. Diagnosis and Differential Diagnosis

The disease is easily diagnosed based on the affected areas, population, and clinical manifestations.

V. Treatment

This disease does not affect health and generally does not require treatment. For cosmetic purposes, radiofrequency and fractional laser treatments can be used to improve the condition.

Radiofrequency Technology

Radiofrequency (RF) technology uses high-frequency electromagnetic waves, ranging from 1 to 40.68 MHz/s, that can conduct long-distance radiation. RF technology for skin aesthetics primarily acts on the dermis and subcutaneous tissue, with a biological effect of thermal action. The heating principle of RF causes changes in dermal collagen and subcutaneous tissue fibers. Collagen protein consists of three strands of helices connected by hydrogen bonds. The thermal effect destabilizes the triple helix structure, causing the collagen to contract and producing an immediate RF effect. Over several weeks to months post-treatment, the body's heat damage repair mechanism is activated, significantly upregulating type I collagen mRNA expression, increasing new collagen production, and enhancing the long-term RF effect. The generated heat also causes the skin to adhere closely to the deep subcutaneous fascia, resulting in tightened and lifted skin. The primary treatment for skin atrophy striae uses monopolar RF, where the distance between the RF emitter and receiver is relatively far, creating a larger electromagnetic field and thus a larger heating area, reaching a depth of 15-20mm. This makes it particularly advantageous for tightening and lifting the skin on the waist, abdomen, limbs, buttocks, and thighs. RF acts on the skin, promoting collagen fiber proliferation and rearrangement while also enhancing lymphatic circulation and accelerating the breakdown of subcutaneous fat cells, thereby improving the appearance of cellulite.
RF treatment procedure steps:

Pre-treatment precautions: Full communication between the doctor and patient is essential, and patients should understand that RF treatment for skin atrophy striae aims only for cosmetic improvement, not a cure. Patients should be aware of the ultimate outcome. Additionally, patients with the following RF treatment contraindications should avoid this treatment:
(1) Presence of metal devices such as pacemakers or artificial hearts.
(2) Pregnant or lactating women and epilepsy patients.
(3) Severe hypertension, coronary heart disease, diabetes, heart disease, thyroid disease, blood disorders, etc.
(4) Severe skin diseases in the treatment area.
(5) Severe keloid patients should use with caution.

Pre-treatment cleansing: Thoroughly cleanse the skin of makeup, including isolation cream and sunscreen, and wipe with non-woven cleansing paper to keep the skin dry. Remove all metal accessories from the body during treatment.

Surface anesthesia/general anesthesia: Generally, RF thermal treatment does not require anesthesia. If injecting or applying lidocaine or similar anesthetics or substances to the treatment area, it may change the natural resistance and unpredictably alter the tissue heating area, potentially exacerbating tissue damage.

In-treatment response: Apply mineral oil or a specialized gel to the treatment area to prevent abnormal discharge from the treatment head and ensure smooth sliding of the treatment head, avoiding friction with the skin. Treatment parameters should be individually adjusted based on the skin texture and appearance of the treatment area and the patient's tolerable heat level. The optimal response post-treatment is a mild erythema formation immediately after the pulse ends.

Post-treatment area handling: Thoroughly clean the treatment area with warm water immediately after treatment and apply moisturizing lotion to relieve dryness and discomfort.

Post-treatment precautions:
(1) Avoid sauna baths on the day of treatment to prevent skin dryness.
(2) Drink at least 1 cup (300mL/cup) of warm water immediately after treatment and 6-8 cups within 24 hours.
(3) Routine sun protection and moisturizing care for the treatment area.
(4) Treatment interval: once every 2 weeks.
(5) Course of treatment: 4-6 treatments per course.

Fractional Laser

Fractional laser, as a new type of laser treatment achieving its effect through focal photothermal action, has epidermal remodeling properties. When the skin tissue absorbs the laser energy, multiple columnar microthermal damage zones (MTZs) form in the skin within 24 hours, where the surrounding normal tissue's keratinocytes migrate to the MTZs for repair. Additionally, the laser energy acts on the deep dermis, causing collagen tissue contraction and degeneration, stimulating collagen proliferation and forming new collagen tissue. Kim et al. used a 1550nm fractional laser to treat six female patients' right-side atrophic striae, showing substantial improvement in striae appearance, normalized skin elasticity, and increased epidermal thickness, collagen, and elastic fiber content after 8 weeks, with only mild to moderate pain and temporary pigmentation. With the application of ablative fractional lasers like the 2940nm Erlaser, clinical results show better improvement in skin atrophy striae compared to non-ablative fractional lasers.
Pixel 2940nm Erfractional laser treatment procedure steps:

Pre-treatment precautions: Full communication between the doctor and patient is essential to exclude the following contraindications:
(1) Scar-prone individuals.
(2) Pregnant or lactating women and epilepsy patients.
(3) Individuals prone to pigmentation or abnormalities.
(4) Patients with active vitiligo, psoriasis, or severe skin diseases in the treatment area.
(5) Psychiatric patients or those with overly high treatment expectations.

Pre-treatment cleansing: Thoroughly cleanse the skin of makeup, including isolation cream and sunscreen, and disinfect the treatment area with New Cleanser.

Surface anesthesia/general anesthesia: Mild pain is usually experienced during treatment; for those with low tolerance, a topical anesthetic cream can be applied.

In-treatment response: The wavelength is set to 2940nm, with micropore diameters typically between 70-100mm, and micropore density adjustable for increased penetration depth. The same area can be irradiated 2-3 times. The treatment endpoint is achieved when mild redness and swelling appear on the treated skin area.

Post-treatment area handling: Apply ice packs to the treatment area for about 30 minutes immediately after treatment.

Post-treatment precautions:
(1) Avoid washing the treatment area for 2-3 days post-laser treatment.
(2) Scabs typically fall off within 7-10 days. Redness may occur in areas where scabs fall off prematurely due to scratching or sauna use, followed by pigmentation that can darken; natural shedding is advised. Ensure sun protection for the treated area.
(3) Redness in the treatment area may last from several hours to days; avoid various irritations.
(4) Some patients may develop pigmentation, usually resolving naturally.
(5) Treatment is recommended once a month, with 2-5 treatments per course.

Source: Skin Atrophy Striae