The diameter of melanomas

Abstract

Background: The mnemonic ABCD, which stands for asymmetry, border irregularity, color variation, and diameter greater than 6 mm alerts physicians to features that suggest melanoma. Although the ABCD criteria are guidelines for diagnosis, clinicians may overlook many melanomas that do not follow the ABCD rule.

Objective: We examined the sensitivity of the diameter portion of the ABCD rule.

Methods: Retrospective study examining the pathology reports of 383 melanomas. Data were compiled for each melanoma regarding its diameter, depth, body location, patient age, and sex. A 95% confidence interval (p=0.05) was used to identify the proportion of melanomas less than or equal to 6 mm in diameter. A two-tailed p value approach (p value =0.05, degrees of freedom=28) was used when evaluating two independent populations, lesions less than or equal to 6 mm and lesions greater than 6 mm in diameter.

Results: A total of 38.21% of melanomas were less than or equal to 6 mm in diameter after processing. Melanomas greater than 6 mm in diameter occurred in significantly older patients and at a greater Breslow's thickness than smaller melanomas.

Conclusions: We demonstrated that a significant proportion of melanomas may be smaller than 6 mm. The ABCD criteria are not absolute; melanomas have many different appearances and start as small lesions.