A 38-year-old woman undergoes wide local excision and sentinel lymph node biopsy for a 1.5 mm superficial spreading melanoma on her right forearm. SLNB is negative for malignancy. She is asymptomatic with no palpable lymphadenopathy or hepatomegaly. Which investigation is most appropriate to complete staging in this patient?

## Staging Investigation for Low-Risk Node-Negative Melanoma ### Clinical Context This patient has **Stage IIA melanoma** (Breslow 1.5 mm, no ulceration, node-negative on SLNB). She is asymptomatic with no clinical signs of metastatic disease. The question asks what imaging is needed to complete staging. ### Why Clinical Examination Alone is Correct **Key Point:** In asymptomatic, node-negative melanoma patients with Breslow thickness ≤2 mm, routine baseline imaging (chest X-ray, abdominal ultrasound, CT, PET-CT) is **NOT recommended** because: - The incidence of occult distant metastases is <2% in stage IIA disease - Sensitivity of imaging for microscopic metastases is low - Cost-benefit analysis does not support routine screening - No evidence that early detection of asymptomatic metastases improves survival - Clinical examination at regular intervals (every 3–6 months) is the standard of care **High-Yield:** Imaging recommendations by stage: | Stage | Baseline Imaging | Surveillance Imaging | | --- | --- | --- | | **IA–IIA (node-negative, ≤2 mm)** | None | Clinical exam only | | **IIB–IIC (node-negative, >2 mm)** | Consider CXR + Abd US | Clinical exam + imaging if symptoms | | **IIIA–IIIC (node-positive)** | CXR + Abd US ± CT chest/abdomen | Regular imaging + clinical exam | | **IV (metastatic)** | Staging CT/PET-CT + brain MRI | Per treatment protocol | **Mnemonic:** **SLIM** rule for melanoma imaging: - **S**ymptomatic disease → image - **L**arge primary (>2 mm) + node-positive → image - **I**ncidental finding on exam → image - **M**etastatic stage → image If none of these apply → **no routine imaging**. ### Surveillance Strategy for This Patient ```mermaid flowchart TD A[Stage IIA melanoma, node-negative, asymptomatic]:::outcome --> B[Clinical examination every 3-6 months]:::action B --> C{New symptoms or signs?}:::decision C -->|No| D[Continue surveillance]:::action C -->|Yes| E[Imaging as clinically indicated]:::action D --> F[Annual dermatology review]:::action E --> G[Chest X-ray, CT, or PET-CT]:::action ``` **Clinical Pearl:** The 5-year survival for stage IIA melanoma is ~85–90%. Routine imaging does not improve this because: - Most recurrences occur in the regional lymph nodes (detected on clinical exam) - Distant metastases in asymptomatic patients are rare and often represent advanced disease - Patient self-examination and regular dermatology follow-up are more cost-effective **Warning:** Do NOT order baseline imaging "just to be safe" in asymptomatic stage IIA patients — this increases healthcare costs and may lead to false-positive findings requiring further workup without improving survival.