Background: Sarcoidosis is a systemic granulomatous disease of unknown etiology, characterized by noncaseating granuloma. Onset of sarcoidosis is thought to be seasonal. However, the data on seasonality is conflicting.

Objectives: Our aim in this study was to determine if there is a relation between onset of sarcoidosis disease and seasonality.

Material and methods: We retrospectively analyzed 473 recent onset symptomatic Sarcoidosis patients diagnosed between 1964-2022. The diagnosis was made based on typical clinic appearance and/or histological finding of noncaseating granuloma. Patients were evaluated according to the month and season of the initial symptom and/or diagnosis, and demographic features.

Results: Monthly onset was lowest in September (3.8%), and highest in May (13.1%). Distribution of disease onset according to seasons was highest in spring (33.2%). Lowest seasonal onset was measured in winter (15.7%). Sex was not found to be related to seasonality of onset. Detailed results are given in the following table (Table 1).

Conclusions: Seasonality seems to be related to onset of Sarcoidosis according to our research. Further studies are required to better understand the importance of these findings.