Extramedullary plasmacytoma of the kidney in an HIV-positive patient: A case report.

Rationale: Extramedullary plasmacytoma (EMP) is a very rare malignant neoplasm arising from clonal proliferation of atypical plasma cells. Most EMPs involve mucosal lymphoid tissue, particularly in the nasopharyngeal area, respiratory tract, and head and neck region. Such neoplasms of the kidney in patients with a human immunodeficiency virus (HIV) infection are extremely rare. Patient concerns: A 55-year-old male who had been diagnosed with HIV 1 year previously presented with a 2-week history of intermittent right abdominal pain and gross hematuria. Diagnosis: Ultrasonography and computed tomography detected a mass that occupied the upper half of the right kidney. A clinical diagnosis of a renal tumor was suspected. Interventions: The patient subsequently underwent a retroperitoneal radical nephrectomy. The postoperative pathological diagnosis was solitary EMP of the kidney. Adjuvant radiation therapy was provided at doses of 50 Gy in 20 fractions. Outcomes: Currently, the patient is alive and disease free at 7 months postoperatively. To the best of our knowledge, this is the first case of a primary renal EMP in a patient with HIV. Conclusion: The present case illustrates that this rare type of solitary EMP associated with acquired immune deficiency syndrome can occur in the kidney. Additionally, although rare, solitary EMP should be considered in the differential diagnosis of a renal mass in HIV-infected patients.