A 52-year-old man presents with a 1.5 cm dark brown lesion on his back with irregular borders and color variation. Clinical examination suggests melanoma. Which investigation is the gold standard for confirming the diagnosis and determining histological subtype?

Explanation

## Investigation of Choice for Melanoma Diagnosis **Key Point:** Excisional biopsy with adequate margins is the gold standard for diagnosing melanoma and determining histological subtype, Breslow thickness, mitotic rate, and ulceration status — all critical prognostic factors. ### Why Excisional Biopsy? 1. **Diagnostic accuracy**: Provides full-thickness specimen allowing complete histological evaluation 2. **Prognostic assessment**: Enables measurement of Breslow thickness (most important prognostic factor) 3. **Margin assessment**: Determines adequacy of excision in one procedure 4. **Subtype classification**: Allows identification of superficial spreading, nodular, lentigo maligna, or acral lentiginous melanoma ### Breslow Thickness — Key Prognostic Factor | Thickness | 5-Year Survival | Stage | |-----------|-----------------|-------| | < 1.0 mm | 95% | IA | | 1.0–2.0 mm | 80–90% | IB–IIA | | 2.0–4.0 mm | 60–75% | IIB–IIC | | > 4.0 mm | < 50% | III–IV | **High-Yield:** Excisional biopsy is recommended with 2–3 mm margins for suspected melanoma (not punch or shave biopsy, which may miss depth assessment). **Clinical Pearl:** Once melanoma is confirmed, sentinel lymph node biopsy (SLNB) is performed for staging in tumors ≥ 1 mm Breslow thickness or with high-risk features (ulceration, high mitotic rate). ### Other Investigations — Supportive Roles - **Dermoscopy**: Aids clinical suspicion but cannot replace histology - **Punch/shave biopsy**: Inadequate for depth measurement; risks understaging - **FNAC**: Poor sensitivity; not recommended for melanoma - **RCM**: Emerging technology; not yet standard for diagnosis [cite:Robbins 10e Ch 25]