PIGMENTED LESIONS IN ACTINICALLY DAMAGED SKIN - HISTOPATHOLOGIC COMPARISON OF BIOPSY AND EXCISIONAL SPECIMENS

Background and Design: A consecutive sample of 46 cases was collected for comparative histologic evaluation. Results of incisional biopsies of cutaneous pigmented lesions interpreted as lentigo maligna, melanom a in situ. or invasive melanoma, and those suggestive, but not diagnos tic, of melanoma were collected. Those lesions that were on actinicall y damaged skin and in which biopsy was followed by complete excision w ithin 6 months were included. Incisional biopsies that removed greater than 50% of the surface area of the lesion were excluded. Results: Of the excisional specimens, 40% demonstrated histopathologic features m ore pronounced than those in the biopsy specimens. Areas of invasive m elanoma not detected in the biopsy specimens were obsen ed in 20% of t he excisional specimens. Accurate diagnosis based on small biopsy spec imens was not always possible because of the absence of a classic lent igo maligna histologic pattern in many cases. The most frequent deviat ion from the pattern was the presence of lentiginous epidermal hyperpl asia within these lesions. Conclusions: These results suggest that lim ited sampling may be inadequate for an accurate diagnosis of pigmented melanocytic lesions on actinically damaged skin. Areas chosen for bio psy may not contain the most advanced areas histologically and may fai l to detect foci of invasive melanoma elsewhere within the lesion.