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The Ugly Duckling: Fairy Tales Are Not Just for Bedtime in Dermatologic Diagnosis

By: Kara Roman, MMS, PA-C

The American Cancer Society reported nearly 96,480 new cases of malignant melanoma (MM) in 2019, making it the 5th most common cancer diagnosis among men and women (1). MM is aggressive, accounting for more than 70% of skin cancer-related deaths, and early detection is key to improved outcomes (2). Both providers and patients need to be aware of MM’s features to help ensure an early and accurate diagnosis. In fact, more than half of the suspicious lesions that result in a diagnosis of melanoma are detected by patients themselves or those close to them (3). The ABCD (asymmetry, irregular borders, multiple colors, and diameter > 5-6 mm) pattern of MM recognition established in 1985 and revised in 2004 with the addition of an E (evolution), has long been a standard for recognizing skin lesions that are suspicious for MM. Application of this diagnostic algorithm to skin lesion evaluation assists patients in knowing when to bring a suspicious lesion to the attention of a healthcare provider, and assists providers in knowing which lesions to biopsy for definitive diagnosis. A new strategy has now been developed to enhance the ABCDE criteria, and its name harkens back to the fable many are familiar with, The Ugly Duckling. The premise is really quite simple. The Ugly Duckling (UD) sign involves comparing pigmented lesions on a presenting patient and searching for one that is obviously different. The different lesion is termed the UD and is considered suspicious for malignancy. This has led some researchers to advocate for adding an “F” to the ABCDE criteria to stand for “funny looking” (3). The addition of this new technique for suspicious lesion identification can be applied synergistically with the older ABCDE framework allowing clinicians to utilize two complementary medical reasoning strategies – intra-comparison lesion analysis and lesion-focused analysis (4). These techniques should allow for earlier recognition and management of malignant melanoma, which is directly tied to improved survival rates. That is something every patient and clinician would agree as being a “happily ever after” ending.

If the age-old fairy tale does not help you improve your diagnostic accuracy in evaluating pigmented lesions, maybe this little tune from your preschool days will help…

           “One of these things is not like the others. One of these things just doesn’t belong.”

Go ahead, sing along if you want. This new diagnostic tool should help to improve outcomes when dealing with suspicious nevi in your practice. If it doesn’t belong, it’s “outta there”!


1.        https://www.cancer.org/cancer/melanoma-skin-cancer/about/key-statistics.html 

2. Gaudy-Marqueste C, Wazaefi Y, Bruneu Y, et al. Ugly Duckling Sign as a Major Factor of Efficiency in Melanoma Detection. JAMA Dermatol. 2017;153(4):279–284.

3. Jensen, JD, Elewski BE. The ABCDEF Rule: Combining the “ABCDE Rule” and the “Ugly Duckling Sign” in an Effort to Improve Patient Self-Screening Examinations. J Clin Aesthet Dermagol. 2015;8(2):15.

4. Ilyas M, Costello CM, et al. The role of the ugly duckling sign in patient education. J Am Acad Dermatol. 2017;77(6): 1088-1095.

See Kara Roman, MMS, PA-C speak in 2020 at a Skin, Bones, Hearts & Private Parts event in Myrtle Beach • Virginia Beach • Orlando