Granulomatous inflammation in histopathological samples: examining the aetiological spectrum, diagnostic challenges,...

Granulomas can be found in different tissues and are associated with a variety of processes. To understand the primary diagnoses is the aim of this study.

We retrospectively described a cohort of patients with a diagnosis of granulomas in histopathological samples over an 11-year period. Demographic characteristics, histopathological pattern and organ involved, diagnostic tests performed (microbiological, radiological and laboratory findings) and final diagnosis were analysed. The principal causes of granulomas were studied according to the organ involved, histopathological characteristics, and the patient's origin. The techniques employed for diagnosis were evaluated.

Six hundred twenty-six patients (median [IQR] age, 50 [33-64] years; 52% male) were analysed. Granulomas were non-necrotising in 56% (350) and necrotising in 24% (150) of cases. The main organ affected was gastrointestinal in 25% (157), ganglionic in 23% (142), pulmonary in 11% (71), hepatic in 10% (65) and skin tissue in 7% (44). The main aetiologies were infectious diseases (138; 22%), predominantly mycobacteria, followed by inflammatory bowel disease (IBD) (14%; 85), sarcoidosis (10%; 65), and neoplasms (9%; 56). In Western European patients, IBD was the main diagnosis (17% [78] vs 4% [7]; p < 0.001), whereas in foreign patients, it was tuberculosis (33% [56] vs 9% [41]; p < 0.001). Microbiological culture was performed in only 34% (210) of cases.

Infectious diseases were the primary cause of granulomas, followed by inflammatory diseases, sarcoidosis and response to neoplasms. The distribution of aetiologies varies according to the organ affected and the nationality of the patient. The implementation of a structured diagnostic algorithm may facilitate the evaluation and management of patients with granulomatous inflammation.