The peculiar dermatoscopic pattern of scalp melanoma.

BACKGROUND: Melanomas developing on anatomic sites other than the trunk and extremities have a special pathogenetic and mutational profile, morphologic characteristics and biologic behaviour. OBJECTIVE: 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. METHODS: 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'. RESULTS: 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. CONCLUSIONS: This study demonstrates that early scalp melanoma combines classic with LM criteria in terms of colours and structures.

Minimizing the dermatoscopic morphologic overlap between basal and squamous cell carcinoma: a retrospective analysis of initially misclassified tumours.

BACKGROUND: Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) have well-established dermatoscopic criteria that make them relatively easy to recognize on a clinical basis. However, even with the addition of dermatoscopy, a morphologic overlap between the two tumours does exist. OBJECTIVES: To analyse the dermatoscopic morphology of clinically and dermatoscopically misclassified BCCs and SCCs, to identify factors causing the erroneous clinical interpretation and, therefore, minimize the morphologic overlap between BCC and SCC. METHODS: Retrospective study including histopathologically diagnosed BCCs or SCCs that had been clinically inversely diagnosed. Their dermatoscopic images were blindly evaluated for the presence of predefined criteria. Descriptive statistics were performed and univariate and multivariate predictors were calculated. RESULTS: A total of 68 cases were included, 41 of which were BCCs and 27 SCCs. Most tumours in both groups were non-pigmented, ulcerated and displayed a polymorphous vascular pattern. The presence of erosions was positively associated to BCC (5.2-fold higher odds, P = 0.05), whereas scales/keratin masses were positively associated to SCC (3.7-fold higher odds, P = 0.07), although marginally not statistically significant. CONCLUSIONS: Clinically misclassified BCCs and SCCs are usually non-pigmented ulcerated tumours. Erosions and keratin masses/scales are more robust criteria as compared to vascular structures for the differential diagnosis between BCC and SCC.