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

Background: Intraepidermal 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.

Objective: We 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.

Methods: We 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.

Results: The 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.

Conclusions: Lack of evaluation of interobserver/intraobserver reproducibility is a limitation. Conclusions: Dermatoscopy is valuable in the diagnosis and differentiation of IEC, sBCC, and psoriasis because of consistent dermatoscopic morphology.