American Board of Internal Medicine (ABIM) Certification Practice Exam

In which situation is a sentinel lymph node biopsy recommended?

1. For all melanoma cases

2. Melanomas less than 1 mm without high-risk features

3. Melanomas of 1- to 4-mm thickness

4. Melanomas over 4 mm regardless of features

The correct answer is: Melanomas of 1- to 4-mm thickness

A sentinel lymph node biopsy is particularly recommended for melanomas that are between 1 mm and 4 mm in thickness. This range indicates a significant potential for metastasis, making it critical to assess the status of the regional lymph nodes. The procedure helps in identifying whether cancer cells have spread beyond the primary site, allowing for appropriate staging and treatment planning. In contrast, melanomas thinner than 1 mm generally possess a lower risk of lymphatic spread, and routine biopsy in these cases may not provide additional clinical benefit. For melanomas thicker than 4 mm, while there is a high risk for metastasis, the recommendation for sentinel lymph node biopsy might vary based on the presence of other clinical factors, making it less universally applicable than for those in the 1 to 4 mm range. Therefore, the approach is tailored to identify significant cases while balancing the risks and benefits of the procedure.