Pseudosarcomatous Sclerosing Peritonitis

Abstract

Chronic lupus peritonitis is uncommon, manifesting as ascites when other signs and symptoms of systemic lupus erythematosus are minimal, thus making diagnosis difficult. It is rarely the initial and only presenting symptom of systemic lupus erythematosus. We report such a case, which clinically and pathologically mimicked a malignant process. At laparotomy homogenous, thick, gray-white, firm tissue covered the bowel and other abdominal organs. Light microscopy showed a highly cellular, predominantly spindle-cell proliferation, raising the possible diagnosis of malignant peritoneal mesothelioma. A conservative approach was taken, and further investigation led to the definitive diagnosis of serositis associated with systemic lupus erythematosus. High-dose immunosuppressive therapy resulted in clinical and serologic improvement. The authors propose the term pseudosarcomatous sclerosing peritonitis to describe this unusually florid peritoneal reaction. The pathologic findings are discussed in the context of other reports of chronic lupus peritonitis, and the differential diagnosis of florid spindle-cell peritoneal reactions is considered.