The Diagnosis of Sarcoidosis.

Sarcoidosis is a diagnosis of exclusion; there exists neither a pathognomonic clinical feature nor a perfect diagnostic test. Missed diagnosis and overdiagnosis are common. A careful history and physical examination look for "footprints" of sarcoidosis or features suggesting alternative diagnoses. Some presentations are classic and do not require tissue confirmation. A tissue biopsy should be performed if doubt exists. Sampling intrathoracic disease by transbronchial or ultrasound-guided biopsy of mediastinal lymph nodes provide high diagnostic yield with low complication rates. Even with tissue confirmation, diagnosis is never secure and follow-up is required to be fully confident of the diagnosis.