American Board of Internal Medicine (ABIM) Certification Practice Exam

What criteria are fulfilled for Lynch syndrome diagnosis?

1. One or more first-degree relatives diagnosed with colorectal cancer after age 50

2. Two or more second-degree relatives diagnosed with colorectal cancer before age 50

3. Diagnosis of at least one colorectal cancer in the patient before age 60

4. Presence of colorectal cancer in siblings diagnosed at any age

The correct answer is: Two or more second-degree relatives diagnosed with colorectal cancer before age 50

For a diagnosis of Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC), several clinical criteria are used to assess familial patterns of cancer described by the Amsterdam criteria and the revised Bethesda guidelines. Among these criteria, a significant marker for Lynch syndrome is the presence of colorectal cancer in multiple family members, particularly at a young age. The option indicating two or more second-degree relatives diagnosed with colorectal cancer before age 50 aligns with the observation that Lynch syndrome often presents with early-onset cancers not only in first-degree relatives but extending to the second degree within families. This emphasizes the hereditary nature of the syndrome and the genetic predisposition to colorectal cancer, making it a central point for identifying individuals who may be carrying mutations associated with Lynch syndrome. In contrast, the other options involve less specific familial relationships or later onset cancers, which do not align as strongly with the established criteria for Lynch syndrome. For instance, the focus is on early-onset cancers within the family trait, rather than just the number of relatives or the age of diagnosis beyond 50, which diminishes the likelihood of identifying Lynch syndrome accurately.