Background: Melanocytic tumours which colonise basal cell carcinomas (BCC) may be considered as either lentigo maligna (LM) (in situ) or invasive melanomas.
Objectives: To highlight the diagnostic approach and long-term prognosis of LM which colonises BCC.
Materials and methods: Using Satter et al.'s classification, we identified a case of BCC colonised by LM and reviewed similar cases in the literature with long-term follow-up.
Results: In the absence of melanocytic extension beyond the lamina propria of the BCC compartment, mixed tumours may be considered as LM colonising the BCC, allowing for less invasive surgery. The absence of long-term relapse in our short series supports this diagnosis, rather than invasive melanomas.
Conclusion: Our case report, review of the literature, and series follow-up illustrate the most recent assessment of melanocytic/BCC tumours, and guide the physician and the pathologist in their recognition and classification, thus allowing them to make the most appropriate therapeutic decisions.
Keywords: basal cell carcinoma; colonization; lentigo maligna; long-term outcome; melanocytic tumor.