Dermoscopy of basosquamous carcinoma

Summary Background Basosquamous carcinoma (BSC) is a rare and potentially aggressive tumour, characterized by clinical and pathological features of both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). It is reported to have a nonspecific clinical presentation, which makes naked‐eye diagnosis a challenge. Objectives To describe the dermoscopic patterns of BSC, which may facilitate early diagnosis and accurate management. Methods This was a retrospective evaluation of clinical and dermoscopic images of histopathologically proven BSC, collected from skin cancer centres in Australia (Perth), Greece (Thessaloniki) and Italy (Naples, Reggio Emilia). Results Twenty‐two tumours were included in the study. Our analysis revealed that the dermoscopic pattern of BSC comprises BCC‐related criteria, as well as features that are known to characterize invasive SCC. The most frequently detected criteria were: unfocused (peripheral) arborizing vessels (73%), keratin masses (73%), white structureless areas (73%), superficial scale (68%), ulceration or blood crusts (68%), white structures (64%), blue‐grey blotches (59%) and blood spots in keratin masses (55%). Notably, all but one of the tumours exhibited at least one BCC‐related plus one SCC‐related dermoscopic feature. Conclusions BSC appears to have overlapping dermoscopic features of BCC and invasive SCC, and detection of at least one dermoscopic criterion of both BCC and SCC should raise suspicion for the tumour. Appreciation of the dermoscopic patterns of BSC might assist in the timely and accurate diagnosis and subsequent optimal management of this unusual and potentially metastatic skin tumour. What's already known about this topic? Basosquamous carcinoma (BSC) is a rare and potentially aggressive tumour, characterized by clinical and pathological features of both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Although dermoscopic characteristics of BCC and SCC have been extensively investigated, those of BSC remain unknown. What does this study add? BSC appears to have overlapping dermoscopic features of BCC and invasive SCC, and detection of at least one dermoscopic criterion of both BCC and SCC should raise suspicion for the tumour.