Histologic features seen in changing nevi after therapy with an 810 nm pulsed diode laser for hair removal in patients with dysplastic nevi.
BACKGROUND
The majority of lasers used for hair removal target melanin as the chromophore. In contrast with other cutaneous applications of lasers, lasers used for hair removal must generate a limited, controlled degree of thermal damage to permanently remove hairs.


OBJECTIVE
To remove excess back hair from two male patients, one with a history of multiple nevi, and prior biopsies showing features of dysplastic nevi, and the other with large nevi greater than 6 mm in diameter and a family history of malignant melanoma.


METHODS
Both patients received monthly treatments with an 810 nm, pulsed, high-power diode laser using a fluence of 20 J/cm2 and 25-30 J/cm2, respectively, and a pulse duration of 30 ms.


RESULTS
Both patients presented 1 month after their last treatment with changing nevi within the treatment areas. Neither patient had clinical inflammation or other alterations suggestive of change in the nevi related to treatment. Thus, the nevi were excised with no mention of the previous laser treatment. The histologic features in all nevi were similar. There was subepidermal blister formation with elongation and disruption of nevus cells. There was homogenization of the collagen within the papillary dermis in all lesions. Only small foci of nevus cells could be identified in the dermis in some of the biopsy specimens. In these biopsy specimens, the dermal stromal matrix homogenization extended into the reticular dermis.


CONCLUSIONS
Laser targeting of nevus cells and surrounding structures may produce clinically atypical nevi in areas previously treated for hair removal. This should be kept in mind, especially in patients with a history of dysplastic nevi or with a personal or family history of malignant melanoma.
Soden
C E
CE
Department of Dermatology, University of Alabama, 1720 University Blvd., Birmingham, AL 35294-0009, USA.
Smith
K
K
Skelton
H
H
D000328:Adult; D001706:Biopsy / Q000379:methods; D004416:Dysplastic Nevus Syndrome / Q000473:pathology*; D006204:Hair Removal / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D053685:Laser Therapy; D008297:Male; D012867:Skin / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology*