SLR - April 2019 - Israel Santander

Retrospective Single-Center Study Evaluating Clinical and Dermoscopic Features of Longitudinal Melanonychia, ABCDEF Criteria and Risk of Malignancy

Reference: Ko D, Oromendia C, Scher R, Lipner SR. Retrospective single-center study evaluating clinical and dermoscopic features of longitudinal melanonychia, ABCDEF criteria and risk of malignancy. J Am Acad Dermatol. 2019 Feb 11. pii: S0190-9622(18)32487-3. doi: 10.1016/j.jaad.2018.08.033

Scientific Literature Review

Reviewed by: Israel Santander, DPM
Residency Program: Medstar Washington Hospital Center, Washington, DC

Podiatric Relevance: Longitudinal melanonychia is a common finding in clinical practice, most concerning for subungual melanoma. Podiatric surgeons routinely use clinical evaluation, such as the ABCDEF criteria, to distinguish benign from malignant. Thus, clinical evaluation sets the threshold for performing a biopsy. This study aimed to evaluate the validity of the ABCDEF criteria as well as dermoscopy findings in patients who underwent a nail matrix biopsy.

Methods: This is a retrospective study of 84 consecutive patients who underwent nail matrix biopsy from January 2011 to November 2017. Clinical photographs, dermoscopy photographs, clinical and histopathological records were reviewed. Factors analyzed included a modified ABCDEF criteria. A for age, B for lesion breadth (3 mm or more, borders), C for change and D for digit most commonly involved, E for extension of pigment onto proximal or lateral nail fold (i.e., Hutchinson sign) and F for family history of melanoma or dysplastic nevi. Other factors evaluated in photographs included band color, width, change and total nail width. Dermoscopy evaluation included nail background color with uniformity of lines present.

Results: Of 84 biopsies, eight were malignant (9.5 percent) and 76 were benign (90.5 percent). The ABCDEF criteria were available for 27 subjects (20 benign and seven malignant, one malignant without data). The two most common factors in both groups were B and C. Malignant group criteria B was seven of eight patients (87.5 percent), and C was five of seven patients (71.4 percent) with only three subjects positive for criterion A, four for D, three for E and one for F. The benign group criteria B, 40 of 69 patients (58.0 percent) and C, 26 of 36 patients (72.2 percent). Band-width percentage of total nail >40 percent (seven of eight cases) was more predictive than band width >3 mm (56 percent of benign cases). Dermoscopy results also raised suspicion for malignancy for band widths of 5.5 mm and 3 mm demonstrating width percentages of 46.4 percent and 48.2 percent, respectively. Overall, band width percentage of total nail > 40 percent was more predictive than band width of 3 mm.

Conclusions: The authors concluded that due to no difference in the number of criteria met between the benign and malignant cases in which a biopsy was performed, there should be less emphasis on the ABCDEF criteria. This study suggests that clinical examination should place more importance on band-width percentage as a predictor of malignancy. Overall, this study suggests a lack of validity in the criteria’s ability to distinguish between benign versus malignant nail changes. Given that the five- and 10-year survival rates are 30 percent and 13 percent, respectively, a lower threshold for a biopsy should be adopted, especially if band-width percentage is greater than 40 percent.  

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