The peculiar dermatoscopic pattern of scalp melanoma

Melanomas developing on anatomic sites other than the trunk and extremities have a special pathogenetic and mutational profile, morphologic characteristics and biologic behaviour.

By retrospectively screening the databases of our centres, we aimed to investigate the dermatoscopic morphology of early scalp melanoma, including in situ and invasive tumours with a Breslow thickness up to 1 mm.

The databases of three specialized centres for skin cancer diagnosis and management in Greece were retrospectively evaluated to retrieve dermatoscopic images of scalp melanomas. Patients' age and sex were recorded, as well as the precise location of the tumour, using 6 possible sub-locations: frontal, parietal, occipital, temporal, nuchal scalp and vertex. The dermatoscopic images were evaluated by 3 independent investigators for the presence of pre-defined criteria. The dermatoscopic criteria included in the evaluation were selected based on available literature and were categorized in 2 groups: 'classic melanoma criteria' and 'lentigo maligna (LM) criteria'.

Of 38 melanomas, 37 (97.4%) displayed brown colour and 23 (60.5%) displayed additional grey or blue colour. The most frequent dermatoscopic criteria were regression (18/38, 47.4%), grey dots/globules (17/38, 44.7%), atypical network (16/38, 42.1%), obliterated follicles (16/38, 42.1%) and angulated lines (15/38, 39.5%). Of 38 melanomas, 28 (73.7%) displayed at least 1 classic melanoma criterion plus at least 1 LM criterion. Of the remaining melanomas, 8 (21.1%) displayed only classic melanoma criteria, 1 (2.6%) only LM criteria and 1 (2.6%) did not exhibit any of the evaluated criteria.

This study demonstrates that early scalp melanoma combines classic with LM criteria in terms of colours and structures.