Abstract
Systemic lupus erythematosus (SLE)is a multisystem autoimmune disease, characterized by clinical heterogeneity, ranging from mild to severe, life-threatening manifestations. Although gastrointestinal (GI) symptoms are frequently encountered during disease course (mainly associated with complications of medication or infection), primary GI involvement due to SLE is rare. Among variable presentations, lupus abdominal serositis (defined as peritonitis if accompanied by symptoms and signs of acute abdomen) and lupus enteritis/mesenteric vasculitis are causes of SLE-related acute abdominal pain. They occur, although not always, in the context of high disease activity and prompt diagnosis and treatment is necessary due to their potential severe complications. However, the diagnosis of these manifestations remains challenging even for experts, especially in cases of "organ-dominant" lupus flares. Exclusion of these rare manifestations from classification criteria increases the likelihood of misdiagnosis and highlights the inherent limitations of classification criteria when the latter are used for diagnosis. Urgent abdominal computed tomography can lead to a prompt diagnosis of these lupus manifestations, especially characteristic for lupus mesenteric vasculitis. Herein, we describe four cases of patients with lupus flare, presenting with acute abdominal manifestations and highlight the potential complexity of diagnostic approach in such situations.