American Board of Internal Medicine (ABIM) Certification Practice Exam

Which cancer is NOT commonly associated with paraneoplastic limbic encephalitis?

1. Lung cancer

2. Breast cancer

3. Thymoma

4. Renal cell carcinoma

The correct answer is: Renal cell carcinoma

Paraneoplastic limbic encephalitis is a rare neurological condition associated with certain types of cancers, where antibodies produced by the immune system mistakenly attack the brain's limbic system. This condition is most commonly linked with specific malignancies, particularly small cell lung cancer, breast cancer, and thymomas. Lung cancer is well-documented as a significant cause of paraneoplastic syndromes, including limbic encephalitis, primarily due to the presence of antibodies such as anti-CRMP-1 or anti-ANNA-1. Breast cancer has also been associated with this condition, albeit less frequently compared to lung cancer. Thymoma, which affects the thymus gland, is similarly associated with various autoantibody syndromes, including limbic encephalitis. In contrast, renal cell carcinoma is not traditionally associated with paraneoplastic limbic encephalitis. While renal cell carcinoma can lead to other paraneoplastic syndromes like hypercalcemia and erythrocytosis, it does not typically trigger the specific immune response that leads to the neurological manifestations seen in limbic encephalitis. This distinction makes renal cell carcinoma the least commonly associated cancer with paraneoplastic limbic encephalitis among the options provided.