Basal-cell carcinoma (BCC) is generally considered to be the most common primary malignant neoplasm in humans. Since they grow exceedingly slowly, most BCCs are innocuous, but if left untreated they can cause extensive destruction of tissue locally, and may lead to death by infiltrating and destroying vital structures.
Predicated on clinico-pathologic correlations, BCC can be basically divided into four distinctive types, namely nodular, superficial, morpheiform, and fibroepithelial (so-called fibroepithelial tumor of Pinkus). From a clinical point of view, nodular BCC occurs commonly on the face as a firm, “pearly” papule or nodule whose surface is covered by telangiectases. In time, the dome-shaped lesions tend to become eroded and then ulcerated. BCCs may occasionally be heavily pigmented due to the presence of melanin within aggregations of basaloid cells thus clinically resembling melanomas.
Dermoscopy is usually performed only in pigmented skin tumors. However, since the dermoscopic hallmark of pigmented BCC, namely, the presence of arborizing vessels, can be appreciated even better in non-pigmented nodular BCC, we recommend dermoscopic examination of these lesions, especially when the differentiation from squamous-cell carcinoma and keratoacanthoma on clinical grounds alone is difficult. The latter ones are characterized by hairpin vessels surrounded by a whitish halo (dermoscopic sign of keratinization) and dotted vessels, whereas BCC nearly exclusively displays arborizing vessels [Kreush and Koch 1996]. Pigmented BCC is commonly characterized by a multicomponent or globular pattern. Besides the pathognomonic vascular pattern consisting of vessels with different diameters and numerous branches, leaf-like areas with an opaque gray-brown to slate-gray pigmentation, mostly situated at the periphery of the lesion, represent an additional dermoscopic clue for the diagnosis of BCC. However, only gray dots/globules and irregularly outlined gray structures are sometimes visible. In conjunction with the complete absence of other dermoscopic melanoma-specific criteria, these gray structures lead to the diagnosis of BCC.