Abstract
Background: Systemic lupus erythematosus (SLE) is a multi-systemic autoimmune disease that affects multiple organ systems. Age at onset has become recognized as having a mediating effect on the clinical manifestation of SLE, late-onset presentations in individuals 50 years of age and older may represent a unique subtype of SLE.
Case Presentation: A 75-year-old Saudi female patient known case of diabetes mellitus, hypertension, osteoarthritis, and morbid obesity. She was presented to the emergency department with a history of shortness of breath and dysuria for 1 week. The patient was admitted to the regular ward and in the following day the patient was developed tachycardia and hypotension and increased serum creatinine 2.59 mg/dl. Then she was shifted to intensive care unit (ICU). In ICU, she was seen by cardiology and electrocardiogram showed atrial fibrillation and T-wave inversion in Lead ll, lll, AVF, and the transthoracic echocardiogram done showed ejection fraction 68% with large effusion around lateral and posterior wall 22 mm and mild effusion around right ventricle. Becks triad was excluded. There was no obvious cause for pericardial effusion at that time, autoimmune disease was suspected, and we consulted the rheumatology department. She was seen by rheumatologist and blood test of autoimmune antibody showed antinuclear antibody positive, anti-dsDNA positive, at that time confirmed diagnosis of SLE.
Clinical Discussion: Serositis is defined as pleural and pericardial effusions, up to 50% of SLE patients pericardial effusion may be seen, it is often minor and asymptomatic and it is more uncommon as an initial symptom.
Conclusion: We report a rare case of late onset of SLE presenting with large pericardiac effusion, which should be considered one of the rare first signs of SLE in older patient.

Key words: Case report, systemic lupus erythematous, multi-systemic autoimmune disease, pericardial effusion.