Fractional CO₂ Laser for Primary Cutaneous Amyloidosis

Primary cutaneous amyloidosis is a localized skin disorder characterized by deposition of amyloid within the skin. Available treatments include topical therapies, phototherapy, systemic medications, and various physical modalities; however, no treatment is considered consistently curative or satisfactory. Fractional CO₂ laser has been proposed as a promising physical treatment because it produces controlled microscopic columns of thermal injury that can ablate amyloid-laden tissue and stimulate dermal remodeling.

This study is a prospective, randomized, parallel-group, controlled clinical trial conducted at the Department of Dermatology and Venereology, Faculty of Medicine, Tanta University, Egypt. A total of 22 patients aged >18 years, of either sex, with clinically and histopathologically confirmed primary cutaneous amyloidosis will be enrolled and randomly assigned in a 1:1 ratio to two groups using a computer-generated randomization table. Allocation concealment will be performed using opaque, sequentially numbered, sealed envelopes.

Participants in the intervention group will receive three sessions of fractional CO₂ laser, with a 4-week interval between sessions and laser power of 12-18 W. Topical anesthetic cream will be applied before treatment, and patients will receive appropriate post-treatment advice. Participants in the control group will receive no active laser treatment during the study period and will be followed for an equivalent duration; supportive measures such as emollients and antihistamines for pruritus may be used when needed.

Clinical assessment will include photography, dermoscopic examination, the Amyloidosis Severity Score, and assessment of pruritus using a visual analogue scale. Skin biopsies will be obtained at baseline and at the final assessment for transmission electron microscopy, including morphometric and image analysis. Adverse events, including redness, swelling, itching, pain, bacterial infection, and bleeding, will also be monitored.

The primary outcome is the change in Amyloidosis Severity Score from baseline to one month after the last laser session, or the corresponding time point in the control group. Secondary outcomes include dermoscopic changes, ultrastructural changes on transmission electron microscopy, change in pruritus severity, patient satisfaction, and treatment-related adverse events.

The expected study duration is approximately six months, from August 2026 to February 2027. Control-group participants will be offered fractional CO₂ laser treatment free of charge after completion of the study follow-up period.

Inclusion criteria

• Patients aged 18 years or older, of either sex. Patients with a clinical and histopathologically confirmed diagnosis of primary cutaneous amyloidosis.

No systemic or topical treatment for primary cutaneous amyloidosis for at least 6 months before enrollment.

Ability and willingness to comply with all study procedures and follow-up visits.

Provision of written informed consent before participation.

Exclusion criteria

• Patients with systemic amyloidosis. Patients with a history of keloid formation. Patients with coagulation disorders. Pregnant or lactating women. Patients with other relevant dermatological diseases that may interfere with study assessment.

Patients with Fitzpatrick skin types V or VI. Patients with diabetes mellitus or renal or hepatic disease. Patients with photosensitivity.