J Clin Pathol 2002;55(Suppl I):A1–A50 A1 Abstracts ............................................................................................... will be presented along with illustrative cases. A cost comparison of Bone marrow Pathology development of therapeutic agents, development of classification sys- tems and clinical trials will be highlighted. 001 EXPRESSION OF CD86 IN ACUTE MYELOGENOUS 003 EXTRAMEDULLARY PRESENTATION OF ACUTE LEUKEMIA IS A MARKER OF DENDRITIC/MONOCYTIC MYELOID LEUKEMIA LINEAGE J Diebold. Hôtel Dieu, 1 Place du Parvis Notre-Dame, 75181 PARIS Cedex D Rondelli, F Re, M Arpinati, N Testoni, P Ricci, C Terragna, P Preda1,D 04, France Ruggeri, M Baccarani, S Tura. Institute of Hematology and Medical Oncol- ogy “Seràgnoli”; 1Division of Pathology, S. Orsola Hospital, University of Extramedullary accumulation of myeloblasts or immature myeloid cells Bologna, Italy realizes tumors which are called myeloid sarcoma in the WHO classi- fication. Such tumours can develop in lymphoid organs, bone (skull, Objective: To determine whether expression of the CD86 costimula- orbit, etc), skin, soft tissue, various mucosae and organs with glandu- tory molecule in acute myeloid leukemia (AML) may identify blast cells lar parenchyma, and the central nervous system (CNS). They may pre- committed to the monocytic/dendritic lineage. cede or occur concurrently with acute myeloid leukemia, reveal blastic Methods: One-hundred-ten consecutive AML patients observed at transformation of chronic myeloproliferative disorders or myelodys- diagnosis were studied by flow cytometry. In selected experiments, plastic syndromes, or relapses in treated patients. The diffuse infiltrate in-vitro cultures with CD34+CD86+ or CD34−CD86+ blasts were is constituted by medium to large cells that are difficult to recognize. performed in the presence of granulocyte -macrophage colony stimu- Imprints are very useful. Today, immunohistochemistry allows the lating factor (GM-CSF) ±tumour necrosis factor α (TNF-α) , or GM-CSF diagnosis and distinguishs variants: granulocytic (MPO+, CD68+, lys- +interleukin 4 (IL-4), respectively, to induce a dendritic differentiation, ozyme positive, CD34+/−), monoblastic (MPO−, CD68+, lysozyme documented by morphological and immunophenotypic assays. T cell positive, CD34−), myelomonoblastic (MPO+/−, CD68+, lysozyme alloreactivity to CD86+ AML cells and leukemic dendritic cells +/−, CD34+/−) or megakaryoblastic (positivity for factor VIII, CD11, (AML-DC) was tested in mixed leukocyte cultures and anti-leukemic CD31). They also often express CD43, CD7, CD79a and CD56 (par- cytotoxic assays. ticularly monoblastic variant with a t(8;21)). The diagnosis is missed in Results: CD86 was expressed in 54% of cases of AML, while about 50% of the cases in the absence of immunohistochemistry. The CD80 and CD1a were only occasionally positive. CD86+ AML myeloid sarcomas should be treated as acute leukemia and they share samples included M5 and M4, but also 47% M0-M1 FAB types, and their prognosis. were more frequently CD14+ (p<0.00001) and CD34− (p=0.00005) than CD86− AML. Six different patterns of CD86+ AML were identified, according to CD34 or CD14 total or partial coexpression. Four sam- 004 CONSIDERATIONS IN DIAGNOSIS OF ples enriched in CD34+CD86+ AML cells differentiated into AML-DC MYELODYSPLASIA CD86+, CD80+, CD40+, CD11c+, HLA-DR++, CD14+/−, that were also CD1a+ or CD83+, after 6 days of in-vitro culture with GM-CSF ±TNF-α A Orazi. Indiana University School of Medicine, Indianapolis, Indiana, CD34−CD86+ AML cells differentiated into AML-DC after 3–5 days USA (n=5 exps), and trisomy 8 was found in two AML and AML-DC sam- ples by fluorescent in situ hybridisation (FISH) analysis. Finally, Myelodysplastic syndromes (MDS) are a clinically heterogeneous AML-DC induced more potent allo-T cell proliferation, cytokine release group of clonal hematopoietic disorders characterized by dysplastic and anti-leukemic cytotoxicity than CD86+ blasts. changes in one or more myeloid cell lines that may occur as primary Conclusion: In AML, CD86 is a marker of monocytic/dendritic lin- diseases or may follow toxic exposures or therapy. MDS have been eage. Since CD86+ blasts may differentiate into DC rapidly, CD86+ traditionally subdivided according to the FAB system (1982) into five AML patients might be optimal candidates for immunotherapy studies, major categories which show different rates of progression to acute both in autologous and in allogeneic settings. myeloid leukemia and overall survival. However, several of the FAB defined MDS groups are prognostically heterogeneous and a more comprehensive approach that takes into consideration other 002 CLINICAL IMPLICATIONS OF THE WHO parameters (e.g. cytogenetics) has been developed by the WHO CLASSIFICATION classification committees. The WHO system distinguishes the following subtypes of MDS: K Foucar. University of New Mexico, Department of Pathology, • Refractory anemia (± ringed sideroblasts). Albuquerque, NM, USA • Refractory cytopenia with multilineage dysplasia (± ringed siderob- The newly proposed WHO classification system of hematolymphoid lasts). neoplasms is founded upon the delineation of lineage (myeloid, B, T, • Refractory anemia with excess blasts (RAEB-1 and RAEB-2). histiocyte, natural killer cell, etc.) and stage of maturation (precursor • Myelodysplastic syndrome, unclassifiable. vs. mature cell of origin). Within each broad category distinct clinical pathologic entities are identified by the integration of clinical, • MDS associated with isolated del (5q) chromosome abnormality morphology, immunophenotype and/or genotype. The large number (“5q-syndrome”). of myeloid disorders are divided into mature (chronic myeloprolifera- The morphological classification of MDS is principally based on the tive and myelodysplastic processes) and immature (acute myeloid percentage of blasts in the BM and PB, the presence of ringed leukemias). The subclassification of acute myeloid leukemias is sideroblasts, and the type and degree of dysplasia. These parameters particularly problematic because the large number of subtypes gener- are usually assessed on bone marrow (BM) and peripheral blood ated from a lineage based system of classification generally do not smears. The presence of dysplasia is not, however, in itself evidence define distinct clinicopathologic entities. Indeed, genotype often is of a clonal marrow disorder, being observed in numerous other con- more useful than lineage assessment in defining distinct clinicopatho- ditions (e.g. B12 and folate deficiencies, exposure to toxic factors or logic subtypes of AML. However, when a strict “entity-based” genetic chemotherapy, viral infections, chronic autoimmune conditions). Prob- approach is applied, a large proportion of AML cases are unclassifi- lems are most commonly encountered in cases of low grade MDS in able. The resulting compromise for the classification of AML consists of which only unilineage dysplasia and no increase in blasts are using genotype to identify the four genetic subtypes of AML that are observed. Cytogenetic abnormalities that are found only in a true clinicopathologic entities, while a lineage-based classification is proportion of MDS cases are helful in confirming a suspected diagno- applied to the remaining cases. A survey of oncologists/pathologists sis of MDS and yield prognostic information. Preliminary evidence has also shown a potential role for flow cytometric immunophenotyping in MDS cases. The value of bone marrow biopsy (BMB) in this group of *Denotes that the author is the presenting author. disorders is generally well established. MDS is usually associated with www.jclinpath.com A2 EAHP abstracts characteristic topographic alterations, among which an important various parasitic infections, examination of the peripheral blood film, finding is the presence of abnormally localized immature myeloid pre- bone marrow aspirate cytology, histology of a trephine biopsy speci- cursors (ALIP) in the central marrow cavities. ALIP positivity is mainly men or other tissue biopsy, and cytogenetic, molecular genetic and present in the aggressive MDS subtypes and is associated with poor immunophenotypic analysis. Even with the application of all these prognosis. Presence of ALIP, however, is not unique to MDS and has diagnostic modalities the cause may remain obscure. If the been reported in reactive hematologic conditions. Immunohistochem- eosinophilia persists for 6 months, causes tissue damage and remains unexplained despite full investigation the designation “idiopathic istry (IHC) can be used to increase the diagnostic accuracy of BMB. hypereosinophilic syndrome” is arbitrarily applied. Some such Both an increase in the percentage of CD34 positive cells and a ten- patients actually represent chronic eosinophilic leukaemia but only the dency of positive cells to form aggregates have been shown to be a subsequent progress of the disease reveals this to be so. When eosi- reliable predictor of leukemic transformation and of poor survival in nophilia is not readily explained, the diagnoses that the pathologist MDS cases, irrespective of their subtype. IHC can be used to confirm must consider include an occult T-cell lymphoma, systemic mastocyto- the presence of dysmegakaryopoiesis in MDS by identifying microme- sis and eosinophilic leukaemia. A bone marrow aspirate and trephine gakaryocytes and other abnormal forms and by showing anomalous biopsy may reveal a lymphoma or an increase of blasts cells, the lat- antigenic