Fractional CO2 Laser in Lichen Amyloidosis With Rapid Pruritus Resolution and Long-Term Remission: Serial PGP9.5 and Dylon Observations With Touch Sensitivity Assessment.

Lichen amyloidosis is a chronic pruritic dermatosis that can be refractory to topical and systemic therapies. We report a 76-year-old Japanese man with severe lichen amyloidosis on the right lower leg (itch numerical rating scale [NRS] 9) treated with a single session of fractional CO2 laser (AcuPulse; combination mode) without anesthesia. Clinical symptoms and adverse events were followed for 2 years. Mechanical hypersensitivity was assessed using an innocuous von Frey filament (0.69 mN) at three predefined sites: the papule center (R1), papule edge (R2), and peripapular area (R3; 1.0 mm from the papule edge). Ten representative papules were tested, and tactile stimulation was applied 10 times per site; response rate was defined as the percentage of stimuli evoking itch or unpleasant sensation. Serial biopsies were obtained at baseline, immediately after irradiation, and at 6 months after treatment for histology (including Dylon staining) and PGP9.5 immunostaining. Pruritus resolved within 1 month (NRS 0) and remained in remission for 2 years without additional treatment. Touch-evoked hypersensitivity, which had been prominent at the papule edge (R2) and peripapular area (R3), was no longer elicited at 1 month (0% response rates at R1-R3). At baseline, PGP9.5 immunostaining showed elongated intraepidermal nerve fibers in the peripapular epidermis. Immediately after irradiation, PGP9.5-positive fibers appeared disrupted/fragmented within micro-ablative columns. At 6 months after treatment, PGP9.5-positive intraepidermal fibers were not evident in any of the examined serial sections. Dylon staining demonstrated that dermal amyloid deposits remained detectable at 6 months. This case illustrates rapid and durable pruritus remission after fractional CO2 laser for lichen amyloidosis, accompanied by serial changes in PGP9.5 staining and improved touch hypersensitivity, despite persistent dermal amyloid deposits.