Dermoscopy of a Plantar Combined Blue Nevus: A Simulator of Melanoma

Abstract

Dermoscopy allows early detection of melanoma also on acral volar skin. The majority of melanocytic nevi on palms and soles may show three major dermoscopic patterns: the parallel-furrow pattern, the lattice-like pattern, and the fibrillar pattern. Melanomas at these sites are characterized by the parallel ridge pattern. We present the case of a 59-year-old woman who had an oval papule of bluish color, measuring 0.6 × 0.9 cm, localized on her left sole, that had been present, unchanged, for more than 10 years. Dermoscopy showed a parallel ridge pattern. The histopathological examination revealed a combined blue nevus. We present this case to underline that on acral volar skin also intradermal nevi, such as combined blue nevi, may dermoscopically exhibit a parallel ridge pattern, simulating melanoma.

Differentiation of combined nevi and melanomas: Case‐control study with comparative analysis of dermoscopic features

“…described previously as indicative of nevi: (1) unstructured homogeneous pigmentation, (2) delicate regular network, (3) homogeneous intensity of pigmentation, (4) regularly arranged brown globules, (5) thinning-out borders (overall), (6) symmetry of shape in one axis, and (7) symmetry of shape in > 1 axis. Fourteen features [1,12] have been described previously as indicative of melanomas: (8) grayblue areas, (9) negative network, (10) broadened-irregular network, (11) irregular intensity of pigmentation, (12) irregularly arranged brown globules, (13) irregularly arranged black dots, (14) radial streaming/pseudopods, (15) border ends abruptly (partly), (16) border ends abruptly (overall), (17) borders thin out (partly), (18) asymmetry of shape, (19) atypical vascular patterns, (20) regression patterns and (21) ulceration. While all aforementioned features were qualitatively assessed for their presence or absence in each lesion, we added one quantitative feature, namely (22) number of colors.…”

Three-Dimensional Melanin Distribution of Acral Melanocytic Nevi Is Reflected in Dermoscopy Features: Analysis of the Parallel Pattern

“…It was also assumed that the slanting of the cornified layer was caused by mechanical pressure, since nevi showing the fibrillar pattern were mostly located on the sole receiving direct pressure from body weight. Panasiti et al [8] reported a case of intradermal nevus on acral volar sites showing a parallel-ridge pattern. Although the lesion was composed of a proliferation of melanocytes localized exclusively to the dermis, its dermoscopic feature revealed a parallel-ridge pattern.…”

“…5g), therefore melanin granules in the cornified layer might have been overlooked, when considering the dermoscopic images of acral nevi. Several textbooks or review articles on dermoscopy have been published to date; however, only melanocyte proliferation at the dermoepidermal junction of the crista limitans was discussed [4, 8], but the importance of melanin distribution in the cornified layer was apparently not emphasized considering the parallel pattern of acral volar sites. Our study using three-dimensional images revealed that the parallel-furrow pattern and the fibrillar pattern would not be presented as seen in dermoscopy, if melanin granules in the basal layer were seen well.…”

“…Dermoscopic patterns of acral nevi are thought to reflect melanin distribution, especially melanin columns, in the stratum corneum. The case of Panasiti et al [8] seems to prove that lack of melanin columns in the cornified layer could not show the parallel-furrow pattern or the fibrillar pattern. …”

Homogeneous Blue Pattern in an Acral Congenital Melanocytic Nevus

“…the parallel-ridge pattern, irregular diffuse pigmentation, multicomponent and serrated patterns [3,4,5,6]. However, Panasiti et al[ 7] reported a combined blue nevus, a well-known benign lesion, which exhibited a parallel-ridge pattern simulating a melanoma.…”