Diffuse Large B-cell Lymphoma Presenting with Protein-losing Enteropathy during Treatment for Systemic Lupus Erythematosus.

Protein-losing enteropathy (PLE) is a rare complication of systemic lupus erythematosus (SLE). A 38-year-old woman with well-controlled SLE developed abdominal pain, lower-extremity edema, anemia, and hypoalbuminemia. The patient was then diagnosed with PLE. Despite treatment with glucocorticoids and cyclophosphamide, persistent hypoalbuminemia was observed. A biopsy was performed using double-balloon enteroscopy due to small bowel lesions, which confirmed the diagnosis of diffuse large B-cell lymphoma. To the best of our knowledge, this is the first reported case of diffuse large B-cell lymphoma mimicking PLE associated with SLE. The possibility of malignant lymphoma should be considered in cases of treatment-resistant PLEs associated with SLE.