‘Rainbow pattern’: a dermoscopic sign of invasive melanoma

Abstract

Summary Background The ‘rainbow pattern’ was initially described as a highly specific dermoscopic feature of Kaposi sarcoma. Since then, it has been reported in many benign and malignant cutaneous tumours, including a few malignant melanomas (MMs). Aim To determine the frequency and presentation of this dermoscopic pattern in primary cutaneous MMs in comparison to other cutaneous tumours. Methods The presence of a rainbow pattern was evaluated in a sample of 1100 dermoscopic images of different melanocytic and nonmelanocytic cutaneous neoplasms. Results The rainbow pattern was observed in 23 of 245 (9.4%) MM and 44 of 855 (5.1%) non‐MM neoplasms. MMs presenting this feature were generally thicker: 82.6% > 1 mm and 43.0% > 2 mm. Compared with non‐MMs, rainbow pattern in MMs was more commonly focal (82.7% vs. 36.4% nonfocal, P = 0.001) and associated with > 2 dermoscopic structures associated with MM (100% vs. 9% with fewer, P = 0.001). Conclusion The rainbow pattern is a dermoscopic sign that can occasionally be observed in invasive MMs. In MMs, this feature is usually associated with other dermoscopic criteria of MM and located in a focal and eccentric area, as opposed to a diffuse and isolated presentation in non‐MM neoplasms.

Do not PASS any melanoma without diagnosis: a new simplified dermoscopic algorithm

“…The identification of melanoma‐specific dermoscopic structures is a common basis in almost all these algorithms, 5–8 but some melanomas might not present any dermoscopic‐specific criteria 17 . These explain why so many structures and vascular patterns suggestive of melanoma have been described in recent years 11–16 . In our study, almost all melanomas presented at least one melanoma‐specific structure, and 82.5% had two or more.…”

“…Previous studies have shown that most melanomas differ from benign melanocytic lesions in the number of colors, asymmetry in colors or structures, and the presence of some specific melanoma-dermoscopic structures. [9][10][11][12][13] Based on these facts, we performed a study to develop a dermoscopic algorithm for the diagnosis of melanoma that fulfilled the following characteristics: accuracy, highest sensibility and specificity to detect cutaneous melanoma; independency of the observer's experience in dermoscopy; and easier to perform in daily practice than previous dermoscopic algorithms.…”

“…Previous studies have shown that most melanomas differ from benign melanocytic lesions in the number of colors, asymmetry in colors or structures, and the presence of some specific melanoma‐dermoscopic structures 9–13 …”

The Many Roles of Dermoscopy in Melanoma Detection

“…The dermatoscopic diagnosis of melanoma is based on the recognition of its chaotic appearance and morphological asymmetry and/or one or more of the following characteristics: atypical network, irregular blotch, irregular dots/globules, irregular streaks/pseudopods, regression structures, white shiny streaks, blue-white veil, atypical vascular pattern, irregular hyperpigmented areas, prominent skin markings, and polygons/angulated lines [ 10 ]. Other dermoscopic criteria that may be found in melanomas are the rainbow pattern (a sign of invasive melanoma) [ 11 ], rosettes (unknown mechanism) [ 12 ], and crusts/erosions (a sign of advanced lesions) [ 8 ].…”

Enhancing Skin Cancer Immunotheranostics and Precision Medicine through Functionalized Nanomodulators and Nanosensors: Recent Development and Prospects

“…It supplements biopsy techniques by providing a complete assessment of the skin lesion to identify the most suitable biopsy sampling site. Melanoma and nonmelanomas are discreetly identified based on specific dermoscopic patterns in the lesions [ 28 , 29 , 30 , 31 ]. Though an effective noninvasive diagnostic tool, dermoscopy can only be applied to the upper dermis [ 27 ].…”