Desmoplastic melanoma arising in lentigo maligna: Implications for general practice

Lentigo maligna (LM) is not uncommonly encountered in general practice and might appear clinically stable for years; however, large or atypical LM can harbour invasive melanoma, particularly the desmoplastic subtype.

The aim of this case study is to emphasise the risk of invasive melanoma in LM and the importance of surgical excision and multidisciplinary referral before considering non-surgical treatment.

This is a case presentation of a man aged 82 years with LM involving most of the scalp. Multiple shave biopsies demonstrated only in situ disease, yet complete excision revealed a focal desmoplastic melanoma (Breslow thickness 5.5 mm). The invasive component was entirely subclinical and undetected on prior sampling. This case illustrates the danger of undertreating invasive disease if topical therapies such as imiquimod or radiotherapy are used. Surgical excision remains the gold standard, and general practitioners play a pivotal role in recognising when referral is required.