[1594] Different Predilection of the Anatomic Distribution of Extra-Lymphoid Involvement in T-Lymphoblastic Lymphoma and B-Lymphoblastic Lymphoma of Childhood

Micah Will, Liqun Yin, Xiayuan Liang. University of Colorado Denver School of Medicine, Aurora, CO

Background: Lymphoblastic lymphoma (LBL) is relatively uncommon compared to lymphoblastic leukemia. LBL may exist with or without a leukemic phase and in some cases may present with extra-lymphoid involvement. Extra-lymphoid presentation may cause a diagnostic challenge if it is not suspected as the differential diagnosis for small round blue cell tumors in children is broad. The characteristic distribution of extra-lymphoid involvement of LBL has not been fully elucidated. We examined a series of pediatric patients with LBL between 1991 and 2011 at our institution.
Design: 43 cases of LBL (23 B-LBL and 20 T-LBL) at Children's Hospital CO were evaluated. All patients were < 20 years of age. Extra-lymphoid involvement is defined as the presence of a tumor mass or tumor cells outside lymph nodes, thymus, spleen, or tonsils. Bone marrow (BM) and cerebrospinal fluid (CSF) involvement was counted separately from extra-lymphoid involvement. The differences of age, sex, and anatomic distribution of extra-lymphoid tumors are compared between B-LBL and T-LBL.
Results: 1) B-LBL tended to occur in the head, bone, and BM more frequent than T-LBL. 2) T-LBL tended to involve body cavities (pleural/pericardial effusion and CSF) and GU system more often than B-LBL. Due to small sample size, only the difference in pleural/pericardial effusion and BM involvement reached statistical significance (p = 0.0183 and p = 0.0281).

  B-LBLT-LBLp value
# of cases 2320 
Mean age (y) 9.311.30.2288*
M:F 14:916:40.1517♠
Extra-lymphoid involvement 14/22 (63.6%)9/20 (45.0%)0.1001♠
 Head5/14 (35.7%)1/9 (11.1%)0.2082♠
 Bone5/14 (36.7.8%)0/9 (0%)0.0595♠
 Soft tissue3/14 (21.4%)1/9 (11.1%)0.4830♠
 Breast1/14 (7.1%)1/9 (11.1%)0.6403♠
 GU1/14 (7.1%)3/9 (33.3%)0.1470♠
 GI1/14 (7.1%)0/9 (0%)0.6087♠
 Skin2/14 (14.3%)1/9 (11.1%)0.6680♠
 Pleural/pericardial effusion1/14 (7.1%)5/9 (55.6%)0.0183♠
BM+ 13/20 (65.0%)6/20 (30.0%)0.0281♠
CSF+ 2/21 (9.5%)4/20 (20%)0.3073♠
*t-test. ♦Fisher exact test.


Conclusions: 1) LBL occurs in variable anatomic locations; 2) The different predilection of extra-lymphoid tissue involvement in B-LBL and T-LBL should be considered in the differential diagnosis when a small round blue cell tumor occurs in a distinct organ system; and 3) B-LBL appears to be more often disseminated systemically (BM+), while T-LBL tends to be more often involve body cavities either through direct extension or through possible stronger ability across the blood-brain barrier.
Category: Hematopathology

Wednesday, March 21, 2012 1:00 PM

Poster Session VI # 234, Wednesday Afternoon

 

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