Prediction without Pigment: a decision algorithm for non-pigmented skin malignancy

Abstract

While there are several published comprehensive stepwise algorithmic methods for diagnosing pigmented skin malignancy, only limited material has been published for the stepwise assessment of non-pigmented lesions. We present a method based on pattern analysis, with a stepwise assessment, first, for ulceration, second, for white clues (defined as white lines, or in the case of a raised lesion any of the keratin clues: dermatoscopic white circles, dermatoscopic white structureless areas or surface keratin), and third, if no ulceration or white clues are present, proceed to vessel pattern analysis.This is a novel method, and apart from the assessment of white clues in raised lesions, it has not been formally tested. The priority of keratin clues in raised lesions over vessel pattern analysis has, however, been verified.It is conceded that this method is less specific than methods which have clues of pigmented structures, and accepting these limitations, Prediction without Pigment is a decision algorithm intended to guide the clinician in the decision as to whether to perform a biopsy rather than consistently leading to a specific diagnosis. Reaching a more specific diagnosis at the end of our flowchart can be achieved by weighing of clues both clinical and dermatoscopic, and that ability can be expected to improve with both knowledge and experience, but no diagnostic method, including this one, can be 100% sensitive in diagnosing malignancy, in particular, melanoma. Taking these limitations into account, any non-pigmented lesion, regardless of pattern analysis, which is raised and firm (nodular) and for which a confident, specific benign diagnosis cannot be made, should be excised to exclude the nodular variant of amelanotic melanoma.

The prevailing dermoscopic vascular pattern in melanoma is influenced by tumour thickness and pigmentation type

“…Although the majority of melanomas in our study revealed a polymorphic pattern, we found that some types of vessels more commonly co‐occur. The co‐occurrence of dotted and linear straight vessels as an indicator for melanoma of intermediate thickness is very well established, and our results again confirm this observation . A clue to differentiate between benign and malignant tumours showing dotted vessels lies particularly in the arrangement, as, for example, dots in melanocytic skin lesions commonly appear regularly distributed.…”

“…D ear E ditor , In nonpigmented skin tumours the diagnosis is based mainly on the evaluation of the vascular morphology and vessels’ distribution dermoscopically . However, to date, no study has formally correlated the prevailing vascular morphology with the Breslow thickness of the melanoma and the amount of pigmentation.…”

The “Rainbow Pattern” and “Crystalline Structures” in a Post-Traumatic Scar

“…These elements are part of a group called "white lines", and are among those only visible with polarized light, the "bright structures" [9].…”

Dermatoscopy of amelanotic and hypomelanotic melanoma

“…Linear curved vessels (“comma vessels”), typical for dermal nevi (“Unna nevi”), have been reported by Menzies et al as a negative predictive factor for melanoma . According to a recent suggestion by Rosendahl et al it is important to differentiate between flat and raised amelanotic melanoma . Flat amelanotic melanomas are typified by polymorphic vessels that include a pattern of vessels as dots.…”

“…Nodular amelanotic melanoma should be suspected in any non‐pigmented nodule that lacks a specific distribution of vascular structures and when a specific benign diagnosis cannot be made with confidence. They also pointed out the importance of other clues such as ulceration and white structures .…”