Donor-Derived Kaposi Sarcoma Presenting as an Infiltrative Renal Allograft Mass

Document Type

Conference Proceeding

Publication Date

5-1-2026

Publication Title

Am J Kidney Dis

Keywords

Urology & Nephrology

Abstract

Kaposi sarcoma (KS) is a vascular neoplasm driven by human herpesvirus-8 (HHV-8) and represents a rare post-transplant malignancy. A 55-year-old man with ESRD from hypertension underwent deceased-donor kidney transplantation. Seven months later, he developed acute kidney injury (creatinine 7.5 mg/dL) and right lower extremity edema. CT revealed a large infiltrative mass in the transplant hilum extending into the graft parenchyma, bladder wall, with extensive retroperitoneal and pelvic lymphadenopathy. Doppler ultrasound suggested extrinsic venous compression of the right external iliac vein with venous outflow obstruction. Venogram and intravascular ultrasound demonstrated severe external compression of the right common iliac vein. Mass biopsy confirmed KS. Serum HHV-8 PCR was positive (1.1 × 10⁵ copies/mL). Immunosuppression was minimized; however, his course was complicated by septic shock, and he died. Retrospectively, pre-transplant serology revealed donor HHV-8 IgG positivity and recipient negativity, raising concern for donor-derived HHV-8 transmission leading to KS in an immunocompromised host. Post-transplant KS occurs in fewer than 1% of recipients and typicallypresents with cutaneous lesions; visceral disease rarely involves the allograft. This case was unusual, presenting with renal dysfunction from venous outflow obstruction due to extrinsic compression of the right common iliac vein. It is also notable because KS likely resulted from donor-to-recipient transmission of HHV-8 in a seronegative host under immunosuppression. Early onset, graft localization, and donor positive/recipient-negative status support donor origin. Donor-derived KS is rare but typically more aggressive, with higher morbidity and mortality. Management includes reduction of immunosuppression or conversion to an mTOR inhibitor, while refractory cases may require systemic chemotherapy. Donor-derived KS can manifest as an infiltrative renal mass, with venous outflow obstruction, rapid progression, and poor prognosis. Awareness of donor-recipient HHV-8 serostatus, early suspicion, and timely modification of immunosuppression are crucial to improve outcomes.

Volume

87

Issue

5

First Page

S42

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