BACKGROUND The purpose of this case report was to present a rare course of pericarditis starting with transverse sinus inflammation in a patient with recurrent chest pain. Typically, the effusion accumulates along the diaphragmatic surface of the back heart, and other localizations, such as the transverse sinus, are uncommon. The main risk factor for pericarditis in Europe is viral infection. In this uncommon case, we strongly suspected underlying Takayasu syndrome. The positive response to treatment with steroids in pericarditis and Takayasu arteritis may be misleading. CASE REPORT A 61-year-old woman was admitted to the Cardiology Clinic because of recurrent chest pain in the form of a retrosternal burning pain with radiation to both arms. With the results of laboratory tests, electrocardiogram, and computer tomography (CT), we excluded acute coronary syndrome, pulmonary embolism, and aortic dissection. In chest CT and transthoracic echocardiography (TTE), we found an effusion around the ascending aorta with uncertain inflammation and in the transverse sinus of the pericardium. After typical pericarditis treatment with non-steroidal anti-inflammatory drugs (NSAIDs) and afterward with steroids, which is similar to Takayasu syndrome treatment, we observed a significant improvement of the patient's clinical condition and no recurrence of chest pain. CONCLUSIONS Despite clinical symptoms, laboratory results, and aorta thickening with surrounding inflammation, Takayasu syndrome was excluded by rheumatologists because of the patient's age. Transverse sinus inflammation is a very rare presentation of pericarditis, but should be considered, especially based on TTE and CT imaging, when other possible causes of retrosternal pain are excluded.