In a young woman with sternal chest pain and bilateral hilar adenopathy, which test is most likely to confirm the diagnosis?

The presence of sternal chest pain and bilateral hilar adenopathy in a young woman raises the suspicion for sarcoidosis, a condition characterized by the formation of non-caseating granulomas in various organs, frequently affecting the lungs. To confirm a diagnosis of sarcoidosis, an endobronchial lung biopsy is often performed. This procedure allows direct access to pulmonary tissue and can reveal the presence of non-caseating granulomas typical of sarcoidosis.

Endobronchial lung biopsy offers several advantages, including being minimally invasive and allowing for both diagnosis and assessment of pulmonary involvement. Additionally, it can be guided by bronchoscopy, which enhances its safety and efficacy.

While other diagnostic methods, such as a PET scan or surgical biopsy, can provide supportive information or assess staging, they are not as definitive as histological confirmation through biopsy. Pulmonary function tests are useful in assessing the impact of the disease on lung function but do not provide a diagnosis on their own.

Overall, the endobronchial lung biopsy is the most effective test for definitively confirming the diagnosis in this clinical scenario, making it the most appropriate choice.