Ascites due to lupus peritonitis: a rare form of onset of systemic lupus erythematosus.

Serositis is commonly seen in systemic lupus erythematosus (SLE). Approximately 16% of patients with SLE have pleural or pericardial involvement. However, peritoneal involvement is extremely rare, and clinically seen in a small group of patients. This is the case report of a 47-year old female with discoid lupus who evolved with systemic manifestations of the disease, characterized by significant abdominal distension and pain, asthenia, weight loss, signs of ascites, and acute non-invasive diarrhea. Exhaustive diagnostic investigation was performed and included laboratory and imaging tests, colonoscopy, and analysis of the ascitic fluid. Besides ruling out the possibility of an infectious, neoplastic, and hemodynamic etiology, the investigation also allowed the confirmation of SLE. Thus, the hypothesis of lupus peritonitis with ascites became viable. The patient was treated with prednisone and chloroquine, with substantial improvement of her condition.