title: MIC2, TdT, bcl-2, and CD34 expression in paraffin-embedded high-grade lymphoma/acute lymphoblastic leukemia distinguishes between distinct clinicopathologic entities.
abstract: We propose that 12E7 (CD99) expression, along with TdT, bcl-2, and CD34 reactivity in lymphoblastic lymphoma (LyL)/acute lymphoblastic leukemia (ALL), distinguishes this group of neoplasms from small noncleaved cell lymphomas (SNCLs) in both pediatric and adult patients, thereby narrowing the differential diagnosis of high-grade non-Hodgkin's lymphomas and acute lymphoblastic leukemias in paraffin sections. 12E7 (CD99) is one of a group of available antibodies that recognizes the product of the mic-2 gene, which was originally identified in ALL. Despite this, most clinicopathological research has focused on the reactivity of 12E7 in a subset of the small round cell tumors of childhood. Although TdT is widely used in the subtyping of blastic leukemias, its use in the distinction of high-grade lymphomas in paraffin sections has been limited. We collected 24 cases of LyL/ALL (13 B-cell and 11 T-cell) and 15 cases of SNCL from 1984 through 1993. We confirmed the diagnoses using morphology and analysis of immunologic data. We performed immunohistochemistry with the 12E7 antibody, TdT, bcl-2, and CD34 on formalin-fixed, paraffin-embedded material. The patients' ages ranged from 4 to 81 years; nine of the study patients were children. Sixteen of the 24 LyL/ALLs stained with 12E7. In contrast, none of the 15 cases of SNCL reacted with this antibody (chi-square P < .0001). A larger percentage of T-cell LyL/ALLs reacted with 12E7 than did B-cell LyL/ALLs (82% v 54%). Sixteen of 20 LyL/ALLs reacted with the anti-TdT antibody, as compared with none of 11 SNCLs (chi-square P < .0001). Six LyL/ALLs were CD34 positive (of 23), and none of the SNCLs were CD34 positive (0 of 12) (chi-square P = .0519). Bcl-2-positive cases were found among both LyL/ ALLs and SNCLs, although they were more prevalent among LyL/ ALLs (92% v 25%; chi-square P < .0001). When one considers the differential diagnosis of a high-grade lymphoma/acute lymphoblastic leukemia, positive reactions with 12E7, TdT, bcl-2, and CD34 support the diagnosis of LyL/ALL over SNCL. Moreover, we present data that suggests that evaluating for TdT in formalin-fixed paraffin-embedded tissue is a more sensitive test than using either 12E7, bcl-2 or CD34 alone.
authors.affiliation: Department of Pathology, New York Hospital-Cornell Medical Center, New York 10021, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Soslow
authors.forename: V
authors.initials: V
authors.lastname: Bhargava
authors.forename: R A
authors.initials: RA
authors.lastname: Warnke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018952:Antigens, CD34 / Q000276:immunology / Q000378:metabolism*; D014408:Biomarkers, Tumor; D001789:Blood Group Antigens / Q000276:immunology / Q000378:metabolism; D015815:Cell Adhesion Molecules / Q000276:immunology / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D004253:DNA Nucleotidylexotransferase / Q000276:immunology / Q000378:metabolism*; D003937:Diagnosis, Differential; D006801:Humans; D016130:Immunophenotyping; D008875:Middle Aged; D016612:Paraffin Embedding; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000276:immunology / Q000378:metabolism*
chemical_list: D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D001789:Blood Group Antigens; D015815:Cell Adhesion Molecules; D019253:Proto-Oncogene Proteins c-bcl-2; C088785:XG protein, human; D004253:DNA Nucleotidylexotransferase