Hidden in Plain Sight: An Uncommon Case of Lupus Ascites

Introduction: Ascites is a common gastrointestinal presentation that causes abdominal swelling and pain. Lupus enteritis (LE), an uncommon cause of ascites, poses a diagnostic challenge due to the non-specific clinical features. Patients may present with heart, kidney, or liver failure but LE can develop in the absence of these conditions. We present an interesting case of lupus ascites in a 43-year-old woman. Case Description/Methods: A 43-year-old woman with a history of SLE presented with acute onset abdominal pain and nausea. She also reported 7-8 episodes of non-bloody diarrhea, nausea, anorexia, 15 lbs weight loss, and low-grade fever. Over the 2 years prior to presentation, she has had slowly progressive abdominal distension. Prior evaluations including abdominal ultrasound, and CT were unremarkable except for a retroperitoneal lymph node. She had abdominal paracentesis, but the cytology was unremarkable. Mycophenolate mofetil was stopped due to recurrent COVID-19 infection; she takes hydroxychloroquine. Physical exam revealed hypertension (141/65 mmHg), tachycardia (100 beats per minute), low grade fever, mild abdominal distension with diffuse tenderness and voluntary guarding. Laboratory data revealed hyponatremia, neutrophilic leukocytosis, normocytic anemia and a high protein gap, elevated serum IgG (Table 1). CT scan revealed dilated small bowel loops, mesenteric edema, and ascites with diffuse mesenteric edema. She received broad spectrum antibiotics due to concern for spontaneous bacterial peritonitis, which was discontinued as ascitic fluid analysis only showed high protein, low SAAG but neutrophils of 104 cells/uL Extensive analysis including CA 19-9, CA-125, hepatic vein doppler ultrasound, pelvic ultrasound was unremarkable. A diagnosis of lupus enteritis was made after ruling out potential diagnoses. She responded promptly to treatment with steroids with the resolution of abdominal pain and swelling. Discussion: Lupus enteritis most commonly occurs during Lupus flares and often occurs with other manifestations of SLE such as Lupus nephritis. However, as in our case, it can be the only presentation along with reduced complements. Typical CT findings of Target sign, Comb sign, and mesenteric fat attenuation can be absent. The diagnosis was made after ruling out other differentials. Treatment with steroids and hydroxychloroquine is effective. We present this case to highlight the importance of prompt diagnosis and treatment of lupus enteritis. Table 1. - Laboratory data on admission Test Value Reference White Cell Count 15.81 4-11 K/uL Absolute Neutrophil 12000 1600 - 7420/uL Hemoglobin 11.1 11.2 - 15.7 g/dL MCV 87 79 - 95 fL Platelets 118 150 - 400 K/uL Total serum protein 7.6 6.0 - 8.5 g/dL Serum Immunoglobulin G 2712 586 - 1602 mg/dL Serum Immunoglobulin A 387 87 - 352 mg/dL Serum Immunoglobulin M 603 26 - 217 mg/dL Alpha 1 Globulin 0.5 0.0 - 0.4 g/dL Gamma Globulin 2.8 0.4 - 1.8 g/dL