Dermatoscopy aids in the diagnosis of the solitary red scaly patch or plaque–features distinguishing superficial basal cell carcinoma, intraepidermal carcinoma, and psoriasis

BackgroundIntraepidermal carcinoma (IEC), superficial basal cell carcinoma (sBCC), and psoriasis are common entities that may all present as well-defined, brightly erythematous plaques. Currently, there are limited data on the dermatoscopic features that differentiate these diagnoses.ObjectiveWe sought to describe the most significant morphologic findings seen on dermatoscopy of IEC, sBCC, and psoriasis, and formulate a diagnostic model based on these features.MethodWe conducted a retrospective observational study using macrophotography and dermatoscopy to evaluate the presence or absence of dermatoscopic features and formulated diagnostic models for each diagnosis. A convenient sample of 300 lesions was collected from 255 patients from two hospital dermatology clinics and 4 private dermatology practices. These comprised 150 cases of sBCC, 100 cases of psoriasis, and 50 cases of IEC.ResultsThe most significant dermatoscopic features of IEC were a clustered vascular pattern, glomerular vessels, and hyperkeratosis. When all 3 features were observed together, the diagnostic probability for IEC was 98%. sBCCs were characterized by a scattered vascular pattern, arborizing microvessels, telangiectatic or atypical vessels, milky-pink background, and brown dots/globules; the diagnostic probability was 99% if 4 of these 6 features were identified. For psoriasis, the significant features identified were a homogenous vascular pattern, red dots, and light-red background, yielding a diagnostic probability of 99% if all 3 features were present.LimitationsLack of evaluation of interobserver/intraobserver reproducibility is a limitation.ConclusionDermatoscopy is valuable in the diagnosis and differentiation of IEC, sBCC, and psoriasis because of consistent dermatoscopic morphology.