**Core Concept**
Port wine hemangiomas, also known as large capillary hemangiomas, are benign vascular tumors that can cause significant cosmetic concerns. The treatment of these lesions aims to minimize scarring and promote optimal cosmetic outcomes.

**Why the Correct Answer is Right**
The best cosmetic results for large capillary hemangiomas are achieved by early and aggressive treatment with systemic corticosteroids. This approach can lead to complete involution of the lesion, resulting in minimal scarring. The mechanism behind this treatment involves the inhibition of angiogenesis and the reduction of vascular permeability, allowing the lesion to involute and preventing further growth.

**Why Each Wrong Option is Incorrect**
**Option A:** Laser therapy is often used to treat port wine hemangiomas, but it is typically reserved for smaller lesions or as an adjunct to systemic treatment. Alone, laser therapy may not be sufficient to achieve optimal cosmetic results in large capillary hemangiomas.
**Option B:** Surgical excision is generally not recommended for port wine hemangiomas due to the risk of scarring and the potential for incomplete removal of the lesion. This approach can lead to suboptimal cosmetic outcomes.
**Option C:** Topical corticosteroids have limited efficacy in treating port wine hemangiomas and are not recommended as a standalone treatment for large capillary hemangiomas.

**Clinical Pearl / High-Yield Fact**
When treating port wine hemangiomas, it is essential to initiate treatment early, as this can significantly improve cosmetic outcomes and minimize the risk of scarring.

**Correct Answer: A. Systemic corticosteroids.**