A 24-year-old female presents with nonspecific symptoms including fever and malaise. A chest x-ray reveals enlarged hilar lymph nodes , while her serum calcium level is found to be elevated. Biopsies of the enlarged hilar lymph nodes would most likely reveal

Sarcoidosis is a systemic disease characterized by noncaseating granulomas in multiple organs. The diagnosis of sarcoidosis depends upon finding these noncaseating granulomas in commonly affected sites. In 90% of cases, bilateral hilar lymphadenopathy ("potato nodes") or lung involvement is present and can be revealed by chest x-ray or transbronchial biopsy. The eye and skin are the next most commonly affected organs, so that both conjunctival and skin biopsies are clinical possibilities. Noncaseating granulomas may be found in multiple infectious diseases, such as fungal infections, but sarcoidosis is not caused by any known organism. Therefore, before the diagnosis of sarcoidosis can be made, cultures must be taken from affected tissues, and there must be no growth of any organism that may produce granulomas. In patients with sarcoidosis, blood levels of angiotensin-conveing enzyme are increased, and this may also be used as a clinical test. In the past, the Kveim skin test was used to assist in the diagnosis of sarcoidosis, but since it involves injecting into patients extracts of material from humans, it is no longer used Reference: Robbins & Cotran Pathologic Basis of Disease, 9edition.