Acquired Angioedema Associated With Systemic Lupus Erythematosus Presenting as Acute Abdomen: A Case Report.

Acquired angioedema (AAE) due to C1 inhibitor deficiency can present as acute abdomen. A 24-year-old woman developed severe abdominal pain and bowel wall edema initially suggestive of hereditary angioedema, but genetic testing excluded it. She later manifested fever, arthritis, rash, and serological abnormalities consistent with systemic lupus erythematosus (SLE). SLE-associated AAE was diagnosed, and immunosuppressive therapy led to clinical and biochemical improvement. This case highlights the importance of considering AAE in patients with unexplained abdominal pain and hypocomplementemia to avoid misdiagnosis and unnecessary surgical intervention.