Malignant Melanomas Often Look Noticeably Different From Other Moles

Allison Gandey

January 23, 2008

January 23, 2008 — Detecting dangerous malignant melanomas might not be as difficult as many fear. Dubbed ugly ducklings, researchers report that melanomas tend to look very different from surrounding moles. They say they are so different that even untrained individuals can often identify worrisome spots that prompt a visit to the doctor's office. The preliminary study appears in the January issue of Archives of Dermatology. "Our study shows that the lay public may be as qualified as physicians to detect malignant melanomas," senior author Ashfaq Marghoob, MD, from the Memorial Sloan-Kettering Cancer Center in New York, told Medscape Oncology.

Using differential recognition, physicians and patients alike can distinguish ugly melanomas from surrounding moles. "We found the sensitivity of the ugly-duckling sign was quite high," Dr. Marghoob added, and he encouraged clinicians to consider this important yet perhaps-overlooked method.

"Detecting early malignant melanoma remains paramount in preventing death," he continued. The public-health message for many years has focused mainly on the ABCD rule — an emphasis that Dr. Marghoob said has been effective. The rule suggests that cancerous melanoma tend to:

A. Be asymmetric.
B. Have border irregularities.
C. Have variations in color.
D. Be large in diameter — often bigger than the size of the eraser of a pencil.

"Unfortunately," Dr. Marghoob said, "this rule does not detect some melanomas, since we have come to appreciate that there are a group of melanomas that do not manifest the ABCD features." But, he added, these melanomas often look very different from surrounding moles and can still be flagged using differential recognition.

"During self skin examination, patients should be looking for lesions that manifest the ABCDs and for lesions that look different from surrounding moles," he said. "This combined approach for looking at skin should improve on the early detection of malignant melanoma."

Improving on the ABCDs of Self Examination

Led by Alon Scope, MD, also from Memorial Sloan-Kettering, the researchers obtained images of the backs of 12 patients from a database of standardized patient images. Each participant had at least 8 atypical moles, and 5 patients had 1 lesion that had been confirmed as a melanoma. A total of 34 study participants — 8 pigmented lesion experts, 13 general dermatologists, 5 dermatology nurses, and 8 nonclinical medical staff — were asked to evaluate the images and identify lesions that looked different from all other atypical moles.

All 5 melanomas and only 3 of 140 benign lesions (2.1%) were classified by two-thirds of the participants as different — so-called ugly ducklings. It was apparent that the malignant melanomas were different to at least 85% of participants. The agreement rate on the benign lesions perceived as being different was 76% at most, the researchers report.

"Although the sensitivity, specificity, and diagnostic accuracy of the ugly-duckling sign depended on clinical expertise, the values for these parameters were good in all subgroups of participants," the authors write.

Sensitivity and Specificity for the Ugly-Duckling Sign

Group All Lesions Perceived as Different,
% (95% CI)
% (95% CI)
– Sensitivity
– Specificity
90 (87 – 95)
85 (83 – 88)
86 (81 – 91)
87 (83 – 90)
Expert dermatologists    
– Sensitivity
– Specificity
100 (91 – 100)
89 (86 – 92)
87 (78 – 98)
93 (90 – 95)
General dermatologists    
– Sensitivity
– Specificity
89 (83 – 96)
86 (83 – 89)
85 (76 – 94)
90 (85 – 93)
Dermatology nurses    
– Sensitivity
– Specificity
88 (80 – 97)
80 (76 – 84)
88 (75 – 100)
79 (64-87)
Nonclinical medical staff    
– Sensitivity
– Specificity
85 (77 – 94)
83 (80 – 86)
85 (76 – 95)
83 (71 – 90)

CI = confidence interval

The researchers point out that the nonclinicians used in this study had some exposure to clinical practice because they were medical staff members. This fact calls into question whether the findings are applicable for screening by the general public. "However," they note, "patients at higher malignant melanoma risk who perform skin self examination may also be better informed and more motivated toward surveillance. Higher-risk patients, particularly those with multiple atypical moles, are probably the individuals for whom melanoma screening efforts are most applicable."

Speaking to Medscape Oncology, Dr. Marghoob emphasized that this preliminary study is based on a small sample in a virtual setting. Efforts are under way to test the ugly-duckling sign in a larger sample of patients and observers.

Dr. Marghoob pointed to another potentially troublesome limitation of differential recognition. Benign lesions such as seborrheic keratosis can appear as ugly-duckling lesions and prompt unnecessary office visits.

The authors conclude: "Further evaluation of the attributes of a malignant melanoma that lead it to be perceived as different — such as specific color, size, and shape — may allow refinement of the ugly-duckling sign and result in even better interobserver agreement."

The researchers have disclosed no relevant financial relationships.

Arch Dermatol. 2008; 144:58-64. Abstract


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