What is the most likely diagnosis for a patient with cough, weight loss, hypercalcemia, and bilateral hilar adenopathy?

The presentation of cough, weight loss, hypercalcemia, and bilateral hilar adenopathy strongly suggests the diagnosis of sarcoidosis. Sarcoidosis is an inflammatory condition characterized by the formation of non-caseating granulomas in various organs, most commonly the lungs. Bilateral hilar adenopathy is often seen on chest X-rays in patients with sarcoidosis and is a hallmark of the disease.

Hypercalcemia occurs in sarcoidosis due to increased conversion of vitamin D to its active form by macrophages within the granulomas, leading to increased absorption of calcium and consequently higher calcium levels in the blood. The combination of these symptoms, particularly the notable finding of hypercalcemia alongside the respiratory symptoms and weight loss, supports a diagnosis of sarcoidosis.

In contrast, pneumonia typically presents with acute respiratory symptoms and is not associated with hypercalcemia or weight loss as prominent features. Chronic bronchitis and asthma do not usually lead to hypercalcemia either and are more about airway obstruction rather than systemic granulomatous disease. Thus, the overall clinical picture aligns best with sarcoidosis.