American Board of Internal Medicine (ABIM) Certification Practice Exam

How is the diagnosis of lymphangioleiomyomatosis confirmed?

1. Blood tests for VEGF-D

2. Imaging studies showing cysts

3. Familial history assessment

4. Biopsy of lung tissue

The correct answer is: Imaging studies showing cysts

The diagnosis of lymphangioleiomyomatosis (LAM) is often confirmed through imaging studies that reveal characteristic cystic changes in the lungs. High-resolution computed tomography (HRCT) scans are particularly useful, showing the presence of numerous thin-walled cysts predominantly in the upper lobes of the lungs. This imaging finding is considered a hallmark of LAM. While other methods can support the diagnosis or rule out alternative conditions, imaging is crucial in establishing the presence of cysts, which are a defining feature of LAM. Blood tests for VEGF-D levels, while they can suggest LAM and have some utility in monitoring the disease, are not definitive for diagnosis on their own. Familial history can help in the context of LAM, especially since it can have a genetic component, but it does not provide direct confirmation of the diagnosis. A biopsy of lung tissue may be performed in some cases; however, it is typically not necessary nor the first-line approach for confirming LAM when typical imaging findings are present. Thus, imaging studies demonstrating cysts serves as the most direct method for confirming the diagnosis of lymphangioleiomyomatosis.