Light and electron microscopic investigation of the process of healing of the naevus of Ota by Q-switched alexandrite laser irradiation

• Published in: Virchows Archiv : an international journal of pathology Vol. 431; no. 1; pp. 63 - 71
• Main Authors: HAKOZAKI, M, MASUDA, T, OIKAWA, H, NARA, T
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.07.1997
• Subjects: Adolescent; Adult; Biological and medical sciences; Cell Nucleus - ultrastructure; Child, Preschool; Dermatology; Female; Humans; Keratinocytes - pathology; Keratinocytes - radiation effects; Keratinocytes - ultrastructure; Laser Therapy; Macrophages - pathology; Macrophages - radiation effects; Macrophages - ultrastructure; Male; Medical sciences; Melanocytes - pathology; Melanocytes - radiation effects; Melanocytes - ultrastructure; Microscopy, Electron; Middle Aged; Nevus of Ota - pathology; Nevus of Ota - physiopathology; Nevus of Ota - radiotherapy; Skin - pathology; Skin - physiopathology; Skin - radiation effects; Skin Neoplasms - pathology; Skin Neoplasms - physiopathology; Skin Neoplasms - radiotherapy; Skin Pigmentation - radiation effects; Tumors of the skin and soft tissue. Premalignant lesions; Wound Healing - physiology; Human; Skin disease; Ota nevus; Treatment efficiency; Melanocyte; Electron microscopy; Pathology; Treatment; Surgery; Irradiation; Melanosome; Cicatrization; Q switched laser
• ISSN: 0945-6317; 1432-2307
• DOI: 10.1007/s004280050070

Melanocytes in the naevus of Ota were destroyed by irradiation using the Q-switched alexandrite laser. This laser is highly selective and highly absorbed by melanosomes. Other cells and tissue components of the dermis remained almost intact. Melanosomes were vaporized or fragmented to subelectron microscopical size, or degenerated. If the irradiated energy was sufficient, melanocytes vanished and large vacuoles several times the size of dermal melanocytes formed at the sites. If it was too weak, dermal melanocytes were also vaporized, but vacuoles formed within them. Nuclei were no longer discernible. Following irradiation macrophages infiltrated the irradiated areas and scavenged degenerated melanosomes and cellular debris. Thus, discoloration of the skin was markedly reduced. Although a few melanocytes and melanophages remained, pigmentation cleared to a satisfactory level. Melanocytes and keratinocytes were also injured in the epidermis; however, the epidermis recovered completely. No scarring was observed.