Thrombotic microangiopathy associated with the hypereosinophilic syndrome.
BACKGROUND
Hypereosinophilic syndrome (HES), defined as persistent marked eosinophilia of unknown origin complicated by end organ damage, is thought to be due to activation of eosinophils and release of substances that are toxic to various cells and tissues. An association between hypereosinophilia and kidney damage is not well documented.


METHODS
We describe two patients with the HES, acute renal failure, and thrombocytopenic hemolytic anemia. Renal biopsy pathology and immunohistochemistry for activated eosinophils were performed.


RESULTS
Renal biopsy revealed glomerular thrombosis, proliferative arteritis, and glomerular and tubulointerstitial eosinophil infiltrates. Ultrastructurally, subendothelial glomerular fibrin deposits and numerous luminal platelets characteristic of thrombotic microangiopathy (TMA) were present. Abundant degranulated eosinophils were localized in glomeruli and the interstitium. Immunofluorescence with specific antibody to eosinophil granule major basic protein (MBP) showed striking extracellular MBP deposition within glomeruli, a marker of eosinophil degranulation. Both patients developed TMA. High-dose glucocorticoids achieved sustained decrease of blood eosinophils and improvement of renal function.


CONCLUSIONS
To our knowledge these are the first documented cases of TMA associated with HES. We propose that products released from degranulated eosinophils caused endothelial injury and microvascular thrombosis. Recognition of this serious renal complication associated with blood eosinophilia should prompt early diagnosis and treatment.
Liapis
Helen
H
Department of Pathology & Immunology, Washington University, St. Louis, Missouri, USA. liapis@path.wustl.edu
Ho
Albert K
AK
Brown
Diane
D
Mindel
Graeme
G
Gleich
Gerald
G
D058186:Acute Kidney Injury / Q000150:complications* / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000743:Anemia, Hemolytic / Q000150:complications* / Q000473:pathology; D006801:Humans; D017681:Hypereosinophilic Syndrome / Q000150:complications* / Q000473:pathology; D007668:Kidney / Q000473:pathology; D008297:Male; D013921:Thrombocytopenia / Q000150:complications* / Q000473:pathology; D013927:Thrombosis / Q000150:complications* / Q000473:pathology