The steadily growing problem of lentigo maligna and lentigo maligna melanoma in Australia: Population-based data on diagnosis and management.

Background/objectives: There are limited population-based data documenting the incidence and management of lentigo maligna (LM) and invasive lentigo maligna melanoma (LMM). We report the data on occurrence and management of LM and LMM in an Australian population.

Methods: Prospective collection of incidence and clinician-reported management of melanoma in situ (MIS; n = 450, capped) and localised invasive melanoma (n = 3251) notified to the New South Wales Cancer Registry over 12-months in 2006-2007.

Results: The estimated annual incidence of all MIS was 27.0 per 100 000 (LM 12.2, non-LM MIS 5.9 and unclassified MIS 9.0). Patients with LM or LMM were on average approximately 10 years older than those with other melanoma subtypes (P < 0.001). The head and neck was the location of 59% of LM, 44% of LMM and <20% of other melanoma subtypes (P < 0.001). The majority of LM and LMM were treated only by specialists. Diagnostic partial biopsies were more frequent for LM and LMM than for other melanoma subtypes, and primary care physicians were more likely than specialists to do a punch partial biopsy than a shave biopsy. The reported median definitive excision margin for LM was 5.0 mm compared with 7.2 mm for non-LM MIS (P = 0.001).

Conclusions: In this Australian population, LM was twice as frequent as other types of MIS. Improved strategies for diagnosis and management are required.