Etiologies of consecutive series of non-necrotizing granulomas.

Background: Sarcoidosis is an idiopathic granulomatous disease characterized by variable organ involvement and non-necrotizing granulomas. Objectives: To determine how often non-necrotizing granulomas are not secondary to sarcoidosis. Methods: A retrospective review was conducted to evaluate all biopsies performed at Mayo Clinic in Jacksonville, Florida from January 1, 1996, to December 31, 2013, showing non-necrotizing granulomas. Results: Three hundred and eight biopsies showing non-necrotizing granulomas met inclusion criteria. The average age was 58.2 years, 60.7% were female, and 85% were Caucasian. The most common symptoms were pulmonary (74.6% of cases), and the most common objective finding was lymphadenopathy (33.8%). The organs biopsied included lung parenchyma (65.3%), intrathoracic lymph nodes (25%), other lymph nodes (1.6%), liver (1.3%), airway (1.3%), skin (1.3%), kidney (0.7%), bone marrow (0.7%), gastrointestinal (0.7%), and one each from the brain, heart, bone, bladder, spleen, tendon, and eye. The suspected diagnosis was confirmed in 224 cases (72.7%). From the remaining 84 cases (27.3%), suspected sarcoidosis was refuted in 9, the initial diagnosis was changed to sarcoidosis in 37 (44%), and in 38, it was changed to a different diagnosis. Sarcoidosis was the final diagnosis in 173 (56%). Conclusion: Sarcoidosis was the leading cause of non-necrotizing granulomas, but in 44% of cases, there was an alternate diagnosis. We estimate that more than a quarter of the initial diagnoses will be changed based on biopsy results and clinical course. (Sarcoidosis Vasc Diffuse Lung Dis 2017; 34: 115-121).