## **Core Concept**
The management of malignant melanoma involves surgical excision with or without sentinel lymph node biopsy (SLNB) depending on the thickness of the tumor. For tumors with a thickness of more than 1 mm, the role of SLNB is still debated, but generally, wide local excision (WLE) is recommended.

## **Why the Correct Answer is Right**
For a malignant melanoma with a thickness of 3 mm, the primary treatment is wide local excision (WLE) of the tumor with a margin of 1-2 cm. Sentinel lymph node biopsy (SLNB) may be considered for tumors with a thickness between 1-4 mm, but it is not the immediate next step for a 3 mm thick melanoma without evidence of lymph node involvement. The presence of a 3 mm thick melanoma necessitates a thorough evaluation and possible surgical intervention to prevent local recurrence and potential lymph node metastasis.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because it does not specify the appropriate management for a 3 mm thick melanoma.
- **Option B:** This option might be considered for thinner melanomas or as part of the workup but is not the immediate next step for a 3 mm thick melanoma with normal groin examination findings.
- **Option C:** While imaging might be part of the metastatic workup, it is not the immediate next step following the diagnosis of a 3 mm thick melanoma without signs of distant metastasis.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the management of melanoma is primarily surgical, with the extent of surgery depending on the thickness of the melanoma. For melanomas thicker than 1 mm, wide local excision is generally recommended.

## **Correct Answer:** D. Wide local excision of the tumor.