Incidence of lentigo maligna in Olmsted County, Minnesota, 1970 to 2007.

BACKGROUND

The incidence of lentigo maligna (LM) may be increasing, but no population-based epidemiologic studies have been performed to our knowledge.

OBJECTIVE

We sought to determine the incidence of LM in Olmsted County, Minnesota, along with overall and recurrence-free survival.

METHODS

Using the Rochester Epidemiology Project, we identified all adult residents of Olmsted County, Minnesota, with a first lifetime diagnosis of LM between 1970 and 2007. Medical records were reviewed to determine demographic, clinical, and surgical data, and incidence and survival were calculated.

RESULTS

Among 145 patients identified, median (range) age at diagnosis of LM was 70 (33-97) years. Treatment changed over time, with Mohs micrographic surgery becoming available after 1986. No patients died of LM; 5 had local recurrence. Estimated local recurrence-free survival at 5, 10, 15, and 20 years after diagnosis was 98%, 96%, 92%, and 92%, respectively. Overall age- and sex-adjusted incidence of LM among adults was 6.3 per 100,000 person-years, increasing from 2.2 between 1970 and 1989 to 13.7 between 2004 and 2007.

LIMITATIONS

Retrospective study design and homogeneous population are limitations.

CONCLUSION

The incidence of LM increased significantly among residents of Olmsted County, Minnesota, over an extended time frame, with incidence being significantly higher among men than women and increasing with age.