Extramedullary infiltrates of AML are associated with CD56 expression, 11q23 abnormalities and inferior clinical outcome.
We evaluated the frequency and prognostic significance of extramedullary infiltrates (EMI) at presentation of acute myeloid leukemia (AML) in adult patients. Of 331 cases with de novo AML, 101(30.5%) had extramedullary infiltrates at diagnosis. The extramedullary manifestations included: lymphadenopathy, splenomegaly, hepatomegaly, gingival hypertrophy, skin infiltrates and involvement of central nervous system (CNS). Patients with EMI had a high initial WBC count and a high proportion of M4/M5 morphological variants. The complete remission rate (CR) with induction chemotherapy was lower in patients with EMI (P=0.0077) and their overall survival was also inferior (P=0.0017). Flow cytometric evaluation of the surface antigens expressed by the leukemic blasts for CD34, TdT, HLADR, CD7, CD19 and CD56 found that only CD56 expression was associated with EMI. The association of CD56 expression with lymphadenopathy was statistically significant (P=0.035). Abnormal karyotypes were found in 50.6% of patients with EMI and 49.7% of patients without EMI. Only 11q23 abnormalities were associated with specific sites of EMI; lymphadenopathy (P=0.0111) and gingival hypertrophy (P=0.0016). Our study of adult AML patients demonstrates that EMI at diagnosis is associated with CD56 expression by leukemic blasts, 11q23 karyotypic abnormalities, low complete remission rate and poor overall survival.
Department of Laboratory Hematology, Princess Margaret Hospital, University Health Network, Toronto, ON, Canada. hong.chang@uhn.on.ca
Hong
H
Chang
Joseph
J
Brandwein
Qi-Long
QL
Yi
Kathy
K
Chun
Bruce
B
Patterson
Bill
B
Brien
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019002:CD56 Antigen / Q000096:biosynthesis*; D002490:Central Nervous System / Q000473:pathology; D002869:Chromosome Aberrations; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics*; D020732:Cytogenetic Analysis; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007951:Leukemia, Myeloid / Q000175:diagnosis* / Q000235:genetics* / Q000276:immunology; D017254:Leukemic Infiltration / Q000235:genetics; D008206:Lymphatic Diseases / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011379:Prognosis; D012307:Risk Factors; D012867:Skin / Q000473:pathology; D015996:Survival Rate; D016896:Treatment Outcome
D019002:CD56 Antigen