JAMES M.GRICHNIKMD, PhD
Amelanotic melanoma (AM), nonpigmented Bowen disease (BD), and nonpigmented basal cell carcinoma (BCC) may appear clinically as red, ill-defined, scaly, and partially eroded plaques, barring accurate diagnosis. All lesions were clinically equivocal and located on the lower legs of women aged 75 (Figure 1), 76 (Figure 2), and 64 years (Figure 3). Histopathologic examination revealed AM (Clark level 4; tumor thickness, 1.75 mm), BD, and BCC, respectively. Dermoscopic evaluation of the AM (Figure 1) exhibited polymorphous vessels typified by dotted, hairpin (inset top left) and linear-irregular vessels (inset top right) together with a central whitish to pinkish veil. A remnant of pigment, seen as a blue homogeneous pigmentation, is a further hint for a melanocytic skin tumor. In BD (Figure 2), characteristic glomerular vessels are seen (inset top right), which are larger than dotted vessels, looped, and regularly arranged in a clustered distribution. The BCC (Figure 3) lacks arborizing vessels, but the presence of multiple small ulcerations (circle) and small blue to gray ovoid nests (square) lead to the correct diagnosis. In these 3 examples of amelanotic tumors, dermoscopy allowed us to distinguish between AM, BD, and BCC by the presence of polymorphous vessels, glomerular vessels, and multiple ulcerations, respectively.
Zalaudek I. Dermoscopy Subpatterns of Nonpigmented Skin Tumors. Arch Dermatol. 2005;141(4):532. doi:10.1001/archderm.141.4.532