**11.3. Treatment of monomorphic PTLD**

For patients with monomorphic PTLD, treatment involves rituximab alone or in combination with systemic chemotherapy, in addition to reduction in immunosuppression. Single-agent rituximab may be utilized in patients with minimal PTLD-related symptoms or low disease burden or if poor performance status or other medical comorbidities preclude the use of systemic chemotherapy. The most commonly employed chemotherapy regimen is R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone); rituximab is omitted in cases of CD20-negative PTLD.

### **11.4. Conclusion(s)**

PTLD can be a life-threatening post-HSCT complication due to the impact of the patient's underlying disease (malignant or nonmalignant) as well as the type and intensity of the transplant conditioning regimen. EBV-negative PTLD is a delayed phenomenon post-HSCT as compared to EBV-positive PTLD. Biomarkers that measure the extent of immunosuppression may have a role in avoiding PTLD and other posttransplant complications. Further investigations are needed to better understand the role of EBV infection in the pathogenesis of the different forms of PTLD in the immunosuppressed patients.
