Kidney involvement in a patient affected by placental site trophoblastic tumor

We report a 42-year-old woman who presents a few days after a spontaneous incomplete abortion at the ninth week of pregnancy with hypertension and nephrotic syndrome. Curettage findings and increased values for the β subunit of human chorionic gonadotrophin were suspicious for a trophoblastic disease. A uterine placental site trophoblastic tumor was diagnosed 2 months later after hysterectomy and treated successfully using chemotherapy. Kidney biopsy showed features consistent with an unusual form of thrombotic microangiopathy characterized by the presence of large thrombus-like structures occluding the capillary lumina and smaller aggregates in the mesangium and along glomerular basement membranes. These deposits were positive for immunoglobulin M, C4, C1q, κ and λ light chains, and fibrinogen. Electron microscopy showed fibrin deposits located primarily in the subendothelial space. The differential diagnosis of this presentation included pre-eclamptic nephropathy, Waldenström disease, lupus anticoagulant glomerulonephritis, systemic lupus erythematosus, and cryoglobulinemic glomerulonephritis. We review the pathogenic mechanisms involved in this case.