information:highlighting, linguistic:translation, structural:scholar_edition
Ugly duckling

One method is the " ugly duckling sign". Correlation of common lesion characteristics is made. Lesions that deviate from the common characteristics are labeled an "ugly duckling", and a further professional exam is required. The " Little Red Riding Hood " sign suggests that individuals with fair skin and light-colored hair might have difficult-to-diagnose amelanotic melanomas. Extra care is required when examining such individuals, as they might have multiple melanomas and severely dysplastic nevi. A dermatoscope must be used to detect "ugly ducklings", as many melanomas in these individuals resemble nonmelanomas or are considered to be " wolves in sheep's clothing ". These fair-skinned individuals often have lightly pigmented or amelanotic melanomas that do not present easy-to-observe color changes and variations. Their borders are often indistinct, complicating visual identification without a dermatoscope.

Amelanotic melanomas and melanomas arising in fair-skinned individuals are very difficult to detect, as they fail to show many of the characteristics in the ABCD rule, break the "ugly duckling" sign, and are hard to distinguish from acne scarring, insect bites, dermatofibromas, or lentigines.