Sarcoidosis is a generalized, systemic, and specific granulomatous disease involving many organs and systems. Diagnosis of sarcoidosis is challenging, especially when mediastinal lymph nodes and lungs are not affected. The symptoms of sarcoidosis depend on its location. Differential diagnosis of sarcoidosis among the other specific granulomatous diseases is difficult, particularly with tuberculosis on biopsy. The etiology of sarcoidosis is still unknown, but this book offers insights and explanations. It also presents guidelines for treatment.