Chronic thrombotic microangiopathy associated with antineoplastic therapy with minimal hematologic effects.

OBJECTIVE: To describe 6 patients who developed progressive renal failure and renal thrombotic microangiopathy (TM) not accompanied by the characteristic hematologic disturbances of TM syndromes. PATIENTS AND METHODS: Portions of renal biopsy specimens from each patient were examined by light and electron microscopy for histopathologic evidence of TM. Antecedent clinical events, laboratory evidence of hemolysis and thrombocytopenia, and clinical outcome were documented. Medical records were reviewed and clinical data, including laboratory values, treatment, and outcome, were recorded.
RESULTS: In each case, a slowly progressive uremia evolved after radiation and/or chemotherapy without laboratory evidence of acute hemolysis or thrombocytopenia. Renal biopsy specimens in all cases showed TM and tubulointerstitial scarring, suggesting both acute and chronic renal injury. Two of the 6 patients underwent plasma exchange therapy without improvement of renal function. Three patients treated with angiotensin-converting enzyme inhibitors for coexisting systemic hypertension remained stable or had mild improvement in renal function.
CONCLUSIONS: A small subset of patients treated for malignancy developed slowly evolving uremia associated with renal TM without marked hematologic abnormalities. In the absence of thrombocytopenia and other typical laboratory findings, the diagnosis of renal TM may be overlooked.