Abstract
BACKGROUND: Systemic lupus erythematosus is an inflammatory disease affecting several organs. Serositis is one of the systemic lupus erythematosus presentations, but peritonitis is a relatively rare presentation. Particularly, it is extremely rare to observe peritonitis as the first presentation of systemic lupus erythematosus. CASE PRESENTATION: Here, we present a case of peritonitis without other symptoms of systemic lupus erythematosus, in a patient who was finally diagnosed with systemic lupus erythematosus. Our patient was a 27-year-old Persian/Caucasian male with fatigue, weakness, weight loss, abdominal distension, massive ascites, and normocytic hemolytic anemia. He did not mention any prior medical conditions and did not use any drugs. There were no signs of thyroid dysfunction, cardiac dysfunction, cancers, infectious diseases, hepatitis, kidney diseases, or other diseases. Low-gradient, high-protein ascites fluid, and positive antinuclear antibody and anti-double stranded DNA were in favor of systemic lupus erythematosus. Corticosteroid pulse therapy led to resolution of ascites, and the patient was discharged with prednisolone and hydroxychloroquine. CONCLUSION: Peritonitis is a rare presentation of systemic lupus erythematosus, particularly as the first presentation and in the absence of other signs and symptoms; however, systemic lupus erythematosus should be considered as one the differential diagnoses for peritonitis when other etiologies have been ruled out.