1. ^*Dermatology Service, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
2. ^†Department of Dermatology, Stanford University Medical Center, Stanford, California, USA
3. ^‡Pathology Services, Veterans Affairs Palo Alto Health Care System, Palo Alto, California, USA
4. ^§Department of Pathology, Stanford University Medical Center, Stanford, California, USA

Correspondence: Susan M. Swetter, MD, Department of Dermatology, Stanford University Medical Center, 900 Blake Wilbur Drive, W0069, Stanford, California 94305, USA. Email: sswetter@stanford.edu

¹Present address: Bethesda Dermatopathology Laboratory, 1730 Elton Road, Ste. 11, Silver Spring, Maryland 20903, USA.

Received 10 August 2004; Revised 6 May 2005; Accepted 14 May 2005.

Abstract

Worldwide, lentigo maligna melanoma (LMM) comprises 4%–15% of cutaneous melanoma and occurs less commonly than superficial spreading or nodular subtypes. We assessed the incidence of melanoma subtypes in regional and national Surveillance, Epidemiology, and End Results (SEER) cancer registry data from 1990 to 2000. Because 30%–50% of SEER data were not classified by histogenetic type, we compared the observed SEER trends with an age-matched population of 1024 cases from Stanford University Medical Center (SUMC) (1995–2000). SEER data revealed lentigo maligna (LM) as the most prevalent in situ subtype (79%–83%), and that LMM has been increasing at a higher rate compared with other subtypes and to all invasive melanoma combined for patients aged 45–64 and 65 y. The SUMC data demonstrated LM and LMM as the only subtypes increasing in incidence over the study period. In both groups, LM comprised 75% of in situ melanoma and LMM 27% of invasive melanoma in men 65 y and older. Regional and national SEER data suggest an increasing incidence of LM and LMM, particularly in men age 65. An increased incidence of LM subtypes should direct melanoma screening to heavily sun-exposed sites, where these subtypes predominate.