A 19-year-old man has a pigmented skin lesion. Which of the following characteristics suggests a dysplastic nevus (atypical mole) rather than a benign acquired nevus?
**Core Concept**
A dysplastic nevus, also known as an atypical mole, is a type of skin lesion that shares characteristics with both benign acquired nevi and melanoma. It is a precursor lesion to melanoma and is often associated with an increased risk of developing skin cancer. Dysplastic nevi typically have a unique combination of features that distinguish them from benign acquired nevi.
**Why the Correct Answer is Right**
Dysplastic nevi are characterized by an irregular shape, with one or more of the following features: asymmetry, irregular borders, varied color, and a diameter greater than 6 mm. The presence of these features suggests that the mole is not a benign acquired nevus. In particular, the irregular shape and varied color of a dysplastic nevus are due to the disorganized growth of melanocytes, which can lead to the formation of abnormal melanin. This can result in a mole that is both darker and lighter in color than the surrounding skin.
**Why Each Wrong Option is Incorrect**
* **Option A:** While a large size can be a feature of a dysplastic nevus, it is not a definitive criterion for distinguishing it from a benign acquired nevus. Many benign acquired nevi can also be large.
* **Option B:** While a change in size can be a feature of a dysplastic nevus, it is not a reliable characteristic for distinguishing it from a benign acquired nevus. Many benign acquired nevi can also change in size over time.
* **Option C:** While bleeding can be a feature of a dysplastic nevus, it is not a specific characteristic that distinguishes it from a benign acquired nevus. Many benign acquired nevi can also bleed, especially if they are irritated or scratched.
**Clinical Pearl / High-Yield Fact**
When evaluating a pigmented skin lesion, it is essential to remember the ABCDE rule: A (asymmetry), B (irregular borders), C (varied color), D (diameter greater than 6 mm), and E (evolving or changing over time). If a mole exhibits any of these features, it is likely a dysplastic nevus and should be evaluated further.
**Correct Answer:** C.