Dermatoscopy of basal cell carcinoma: morphologic variability of global and local features and accuracy of diagnosis

BACKGROUND: Early detection of basal cell carcinoma (BCC) is crucial to reduce the morbidity of this tumor. OBJECTIVE: We sought to investigate the variability and diagnostic significance of dermatoscopic features of BCCs. METHODS: We conducted retrospective dermatoscopic analysis of 609 BCCs and 200 melanocytic and nonmelanocytic lesions, and assessment of interrater reliability of dermatoscopic BCC criteria. RESULTS: Lesions included nonpigmented (15.1%), lightly pigmented (33.2%), pigmented (42.7%), and heavily pigmented (9%) BCCs. Classic BCC patterns including arborizing telangiectasia (57.1%), blue/gray ovoid nests (47.5%), ulceration (39.2%), multiple blue/gray globules (26.1%), leaflike areas (15.9%), and spoke-wheel areas (9%) were significantly increased in pigmented BCCs compared with nonpigmented and heavily pigmented BCCs (P = .0001). Among nonclassic BCC patterns, we detected short fine superficial telangiectasia (10%) and multiple small erosions (8.5%), and described two new patterns named "concentric structures" (7.6%) and "multiple in-focus blue/gray dots" (5.1%). Dermatoscopic features suggestive of melanocytic lesions (eg, multiple brown to black dots/globules, blue/white veillike structures, and nonarborizing vessels) were observed in 40.6% BCCs and significantly increased in heavily pigmented BCCs (P < .0001). Expert observers provided an accurate (sensitivity: 97%) and reliable (K: 87%) dermatoscopic diagnosis of BCC, although a significant difference in terms of specificity (P = .0002) and positive predictive value (P = .0004) was found. Arborizing telangiectasia, leaflike areas, and large blue/gray ovoid nests represented reliable and robust diagnostic parameters. LIMITATION: The study was retrospective. CONCLUSION: BCCs show a large spectrum of global and local dermatoscopic features; heavily pigmented BCCs show the most challenging combinations of dermatoscopic features.