[1424] Characterization of Anatomic Distribution of Acute Leukemia Relapse in the Pediatric Patients

Kevin Lee, Amy McGranaham, Tyler Winkler, Xiayuan Liang. Children, Aurora, CO; University of Colorado Denver School of Medicine, Aurora, CO

Background: Acute leukemia arises from the bone marrow (BM) and is the most common malignant neoplasm in childhood. Although the BM recurrence occurs in most of relapsed patients, both acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML), unusual extramedullary presentations/lesions are seen in some cases and may cause a diagnostic challenge. To better understand and characterize the pattern of anatomic distribution in acute leukemia relapse, we examined a series of relapsed cases in pediatric patients of both ALL and AML at our institution.
Design: 104 cases of relapsed acute leukemia (46 AML and 58 ALL) between 9/1999 and 8/2012 at Children's Hospital Colorado were evaluated. All patients were < 20 years of age. The anatomic locations at relapse are divided into 3 groups: BM, cerebrospinal fluid (CSF), and sites other than BM and CSF. The differences of incidence of each location group are compared between AML and ALL by Fisher exact analysis.
Results: 1) BM is the most common site at relapse in both ALL and AML. 2) Relapses to the central nervous system (CNS) manifested by CSF involvement are more common in ALL than AML (p = 0.04). 3) AML which relapses to sites other than BM and CSF occurred more frequent than ALL (p = 0.022). 4) No ALL relapse was seen outside of "immunologically privileged" sites (CNS, eye and testes).

  AMLALLp value
# of cases 4658 
BM Relapse 37/46 (80%)48/58 (83%)0.800
CSF Relapse 10/46 (22%)25/58 (43%)0.040
Relapse at site other than BM or CSFSkin60 
 Vitreous Fluid21 
 Total11/46 (22%)4/58 (7%)0.022

Conclusions: 1) Both AML and ALL most often relapse in the BM but differ in their patterns of involvement of other tissues. 2) Other than the BM, ALL relapse is much more likely to occur in CSF than any other sites while AML showed an equal distribution among CSF and other sites. 3) Not including the BM, ALL only relapsed at immunologically privileged sites (CNS, eye and testes) while AML showed a wide tissue distribution, suggesting that the tissue environment and/or lineage associated cytokines may mediate and direct the dwelling of leukemic blasts at relapse. Understanding of these patterns will help to ensure accurate pathologic diagnosis.
Category: Hematopathology

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 242, Wednesday Morning


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