American Board of Internal Medicine (ABIM) Certification Practice Exam

What quality is most important in staging melanoma using sentinel lymph node biopsy?

1. Thickness of lesion

2. Presence of ulceration

3. Patient's age

4. Histological type

The correct answer is: Thickness of lesion

The thickness of the melanoma lesion, also known as the Breslow depth, is a critical factor in staging melanoma when using sentinel lymph node biopsy. This measurement indicates how deep the tumor penetrates into the skin and correlates directly with the risk of metastasis to regional lymph nodes. Thicker lesions are statistically associated with a higher likelihood of lymph node involvement, making this parameter essential for staging and guiding treatment decisions. While other factors such as the presence of ulceration, the patient's age, and the histological type of melanoma are also important considerations in the overall management of the disease, they do not primarily dictate the sentinel lymph node staging process. Ulceration, for example, indicates a worse prognosis and can influence treatment decisions, but it does not have the same direct impact on predicting the likelihood of lymph node metastasis as lesion thickness. Similarly, the patient's age and histological subtype can affect prognosis but are not the main criteria for determining the stage of melanoma during sentinel lymph node biopsy. Therefore, the thickness of the lesion stands out as the most critical factor in this context.