CONSULT ROUNDS: Post Bone Marrow Transplant Thrombotic Microangiopathy(TMA)

Someone presents to you withclinical signs of TMA 3-4 weeks following a BMT.  TMA after a stem cell transplant doesn't follow the classic route of HUS or TTP but is more syndromic of TMA( low platelets, microangiopathic anemia, low haptoglobin, elevated LDH, renal failure, some proteinuria and hypertension)
The etiology is anything that can be damaging to the endothelium ( Calcineurins, other chemotherapy agents, total body radiation, GVHD or the primary cancer returning back with a TMA component)
The presentation may involve the kidney as the primary site. The acute TMA kidney biopsy will resemble that of pre eclampsia with or without mesangiolysis and intraglomerular and renal arteriloar thrombi and double contouring as well if there is chronic TMA ( MPGN pattern of injury).
Risk factors for TMA post transplant include female race, cytoxan high dose induction, TBI without shielding and CNI and sirolimus use.
Many people consider chronic TMA in post BMT patients a radiation nephropathy and TBI as the major risk factor and the damaging the endothelium.  Does pheresis help in this instance? Less likely as its more of a direct insult on the endothelium and not really an antibody mediated that can be removed with pheresis.
Left image courtesy: Kidney International