Primary breast diffuse large B-cell lymphoma in a patient with systemic lupus erythematosus: A case report and review of the literature.

Rationale: Pilot studies have reported that patients with systemic lupus erythematosus (SLE) appear more likely to develop into neoplasia, especially lymphatic hyperplasia diseases. To our knowledge, this is the first case report of the concomitant onset of SLE and primary breast diffuse large B-cell lymphoma (PB-DLBCL).

Patient Concerns: We reported an unusual case of the occurrence of primary breast diffuse large B-cell lymphoma in a 25-year-old female patient who had been diagnosed with SLE and treated with immunosuppressive drugs for about 4 years. She presented a 7-week history of a painless mass above the left breast and no history suggestive of any nipple discharge, fever, and weight loss.

Diagnosis: Ultrasonography of the breast showed that there was 1 mass in the left breast. After breast mass surgical resection, histopathological examinations were performed and revealed that it was primary breast diffuse large B-cell lymphoma.

Interventions: Treatment strategy with vincristine and dexamethasone was used to improve symptoms. However, the patient's renal function deteriorated and the blood potassium rose continuously and she and their family members refused the follow-up treatments.

Outcomes: The patient died 8 months after she was discharged from the hospital.

Lessons: PB-DLBCL is a rare occurrence in SLE patients. Therefore, a careful examination is very important in SLE cohort, as activity of the disease and malignancy may mimic each other. Meanwhile, when symptoms cannot be explained or insensitive to treatment, the occurrence of malignant tumors must be highly considered.