**Core Concept**
Becker's nevus is a benign, congenital skin lesion characterized by an overgrowth of hair and hyperpigmentation, typically appearing in the presternal, axillary, or shoulder region. It is often associated with an underlying hormonal imbalance, particularly androgen excess.

**Why the Correct Answer is Right**
Becker's nevus is thought to occur due to an abnormal response to androgenic hormones, which stimulate the growth of hair follicles and melanocytes. The lesion is often seen in adolescent males, suggesting a link to pubertal hormonal changes. The exact pathogenesis remains unclear, but it is believed to involve an interaction between androgens and the hair follicle, leading to an abnormal increase in hair growth and pigmentation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Becker's nevus is not a form of melanoma, which is a malignant skin cancer characterized by uncontrolled cell growth and tumor formation.

**Option B:** This option is incorrect because port-wine stains are congenital vascular malformations that appear as pink or purple lesions on the skin, often associated with neurofibromatosis type 1.

**Option C:** This option is incorrect because epidermal nevi are benign skin lesions that appear as flat or slightly raised patches of skin, often associated with neurocutaneous syndromes.

**Clinical Pearl / High-Yield Fact**
Becker's nevus is often seen in adolescent males, suggesting a link to pubertal hormonal changes. This fact is useful for clinicians who may encounter this condition in the context of a patient's overall hormonal and dermatological history.

**Correct Answer:** D.