## Core Concept
Bowen's disease is a form of **intraepithelial squamous cell carcinoma**, which is a type of skin cancer that remains confined to the **epithelium**. It presents as a slow-growing, scaly plaque, often on sun-exposed areas. Given its superficial nature, treatment options focus on local destruction or removal of the lesion.

## Why the Correct Answer is Right
The correct approach for managing Bowen's disease, especially when the lesion is **incompletely excised**, involves ensuring complete removal of the tumor while considering the cosmetic and functional outcomes. **Mohs surgery** is a highly effective technique for treating Bowen's disease, especially in cosmetically sensitive or functionally critical areas. It allows for **complete margin assessment**, ensuring that all cancerous cells are removed while sparing as much normal tissue as possible.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is not provided, but typically, treatments like simple excision might not always ensure clear margins without the precision of Mohs surgery.
- **Option B:** This option is also not provided, but treatments such as cryotherapy or topical treatments (e.g., 5-fluorouracil) might be considered for Bowen's disease but are usually reserved for smaller lesions or those in less critical areas.
- **Option C:** Similarly, without specifics, other treatments like laser therapy could be considered but might not offer the margin control that Mohs surgery provides.

## Clinical Pearl / High-Yield Fact
A key point to remember is that **Mohs surgery** offers the advantage of **complete margin assessment** during the procedure, making it highly effective for treating **incompletely excised** lesions like Bowen's disease, especially in sensitive areas or when cosmesis is a concern.

## Correct Answer Line
**Correct Answer: D. Mohs surgery**.