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J Thiele

Publications and source records attributed to J Thiele.

At least 145 records · Page 8Linked to original sources
PubMed1997

[Radiologic imaging of MALT lymphoma. (Comparison between stomach roentgen image, computerized tomography and magnetic resonance tomography].

The new classification of primary lymphomas of the stomach according to the MALT concept is very promising in therapy planning and prognostic estimation. This new classification sets strict requirements for imaging diagnostics. Besides endosonography which allows the determination of the infiltration depth in stages E I1 and E I2 in an excellent manner, computed tomography and, possibly, magnetic resonance tomography are indispensible for evaluation of higher stages and of the resectability of a lymphoma. Further MRI examinations are recommended.

Female↗
PubMed1996

Characterization of the binding specificity of Anguilla anguilla agglutinin (AAA) in comparison to Ulex europaeus agglutinin I (UEA-I).

Using immunochemical and immunohistochemical methods, the binding site of Anguilla anguilla agglutinin (AAA) was characterized and compared with the related fucose-specific lectin from Ulex europaeus (UEA-I). In solid-phase enzyme-linked immunoassays, the two lectins recognized Fuc alpha 1-2Gal beta-HSA. AAA additionally cross-reacted with neoglycolipids bearing lacto-N-fucopentaose (LNFP) I [H type 1] and II [Le(a)] and lactodifucotetraose (LDFT) as glycan moieties. UEA-I, on the other hand, bound to a LDFT-derived neoglycolipid but not to the other neoglycolipids tested. Binding of AAA to gastric mucin was competitively neutralized by Le(a)-specific monoclonal antibodies. UEA-I binding, on the other hand, was reduced after co-incubation with H type 2- and Le(y)-specific monoclonal antibodies. According to our results, AAA reacts with fucosylated type 1 chain antigens, whereas UEA-I binds only to the alpha 1-2-fucosylated LDFT-derived neoglycolipid. In immunohistochemical studies, the reactivity of AAA and UEA-I in normal pyloric mucosa from individuals with known Lewis and secretor status was analysed. AAA showed a broad reaction in the superficial pyloric mucosa from secretors and non-secretors, but AAA reactivity was more pronounced in Le(a+b-) individuals. On the other hand, UEA-I stained the superficial pyloric mucosa only from secretor individuals. A staining of deep mucous glands by the lectins was found in all specimens. Both reacted with most human carcinomas of different origin. Slight differences in their binding pattern were observed and may be explained by the different fine-specificities of the lectins.

Agglutinins↗
PubMed1996

Effect of interferon therapy on bone marrow morphology in chronic myeloid leukemia: a cytochemical and immunohistochemical study of trephine biopsies.

The effect of interferon (IFN) therapy on bone marrow features in chronic myeloid leukemia (CML) has been studied on successive trephine biopsies (mean interval 13 +/- 8 months) by cytochemical and immunohistochemical methods in combination with morphometry and in comparison with a control group of patients who received monotherapy by busulfan (BU). Following IFN administration (IFN-alpha frequently in combination with IFN-gamma), there was a decrease in neutrophil granulopoiesis accompanied by a significant expansion of erythroid precursors and increased numbers of hemosiderin-laden macrophages. These changes corresponded with the hematologic response in 21 of the 25 patients investigated. Numbers of megakaryocytes and reticulin/collagen fiber density increased during treatment. Most conspicuously, in responding patients atypical micromegakaryocytes, usually characterizing CML, were partially replaced by normal-sized cells of this lineage. These features are in keeping with the assumption of a reappearance of the normal hematopoietic cell clone as the result of IFN therapy, which was not found in the BU-treated control group. On the other hand, a relevant subpopulation of micromegakaryocytes (about 30%) was still maintained. This result probably relates to the failure to improve myelofibrosis more effectively. Analysis of cell proliferation (proliferating cell nuclear antigen-PCNA) and apoptosis (in situ end labeling) revealed a reduction in PCNA labeling and increased numbers of cells undergoing programmed death. Identification of the activated subset of macrophages (alpha-D-galactosyl residues expression) by appropriate lectin histochemistry disclosed an increase in the number of GSA-I binding cells. These findings were exclusively limited to IFN administration and reflect an inhibitory effect of IFN on cell proliferation and stimulation of programmed cell death. The latter phenomenon probably results in increased phagocytosis of clonally transformed myeloid cells by GSA-I-positive (activated) macrophages.

Adult↗
PubMed1996

Apoptosis in acute myeloblastic leukemia: follow-up study on trephine biopsies of the bone marrow.

A clinicopathological study on 87 adult patients presenting with "de novo" acute myeloblastic leukemia (AML) was performed to assess the rate of apoptosis before and during chemotherapy and its predictive impact on clinical course. Evaluation included trephine biopsies of the bone marrow and the situ end-labeling technic (ISEL) for the identification of programmed cell death in large and intact hemopoietic tissue areas. In comparison with a control group of 21 patients without any hematological disorder, morphometric analysis revealed no significantly different numbers of apoptotic cells in AML at the onset of disease and following sequential examinations at intervals ranging between 10 to 19 months. Moreover, the incidence of programmed cell death was not associated with the subgroups of the FAB classification and statistics failed to show a relationship with survival or remission status. In conclusion, these findings are in keeping with the assumption that apoptosis occurs with the same frequency in recovering normal hemopoiesis in complete or partial remission, in manifest AML and relapse. In the latter conditions, enhancement of proliferation is not associated with an increase in the apoptotic index.

Acute Disease↗
PubMed1996

Idiopathic primary osteo-myelofibrosis: a clinico-pathological study on 208 patients with special emphasis on evolution of disease features, differentiation from essential thrombocythemia and variables of prognostic impact.

A retrospective clinico-pathological study was performed on 208 consecutively recruited patients (94 males, 114 females, median age 67 years) with idiopathic (primary) osteo-/ myelofibrosis (IMF). According to bone marrow histology (cellularity) as well as extent (semiquantitative grading) and quality (reticulin/collagen) of myelofibrosis, stages of the disease process were determined. At closure of this study (observation time 65 months) 133 patients were dead and 75 alive and median survival was 56 months. The wide spectrum of clinical signs and symptoms and laboratory data on admission was reflected by a corresponding variety of histological features. Significant differences of hematological values could be calculated between patients with or without early reticulin fibrosis (fiber scores 0 and 1) and advanced fibro-osteosclerotic stages (fiber scores 2 and 3). Evolution of disease features was elicited by longitudinal follow-up studies and sequential bone marrow biopsies. Morphometric assessment of fiber density in patients without preceding chemotherapy revealed an unpredictable and varying progression of myelofibrosis associated with alterations of certain laboratory parameters (hemoglobin level, spleensize, thrombocytosis). Differentiation from essential (primary) thrombocythemia (ET) was required in 25 patients who fulfilled the postulated diagnostic criteria. In fact, this group was consistent with hypercellular, early stages of IMF without relevant reticulin fibrosis and an excessively raised platelet count (> or = 1000 x 10(9)/1). Discrimination was only feasible by regarding histology carefully, particularly abnormalities of megakaryopoiesis and follow-up data. Parameters of predictive value indicating a significant loss in life expectancy in comparison with a sex- and age-adjusted normal population included: age (> or = 60 years), hemoglobin levels (< or = 10 g/dl), thrombocyte count (< or = 600 x 10(9)/1) and the presence of myeloblasts and promyelocytes. Statistical analysis disclosed that in the so-called early stages of IMF without relevant myelofibrosis, findings indicative for extramedullary hemopoiesis or generalization of the disease process exerted an unfavourable influence on survival.

Aged↗
PubMed1996

Interferon therapy, but not busulfan restores normal-sized megakaryopoiesis in CML--a comparative histo- and immunomorphometric study.

To assess possible alterations of megakaryocytes associated with interferon (IFN) and busulfan (BU) therapy of Ph(1+)-CML, an immunohistochemical and morphometric study was performed on trephine biopsies of the bone marrow taken before and at varying intervals during treatment. For the identification of megakaryopoiesis and its endoreduplicative activity the monoclonal antibodies CD61 (anti-platelet glycoprotein IIIa) and PC10 raised against proliferating cell nuclear antigen (PCNA) were used. We compared 60 specimens from 20 patients following IFN alpha-2b administration (in combination with IFN gamma in seven patients) with 57 specimens from 22 patients after monotherapy with BU. A close correlation with clinical follow-up studies revealed that in the IFN-treated group the prevalence of atypical micro-megakaryocytes, usually characterizing CML, was conspicuously reduced in repeatedly taken bone marrow samples. Initially, even an increase in size which was levelled to normal values during maintenance therapy was observed. These features were most prominently expressed in the 13 patients with a complete hematologic and/or partial cytogenetic response. Associated with this phenomenon was a significant enhancement of the PCNA-labelling index which indicated a stimulation of endoreduplicative (endomitotic) activity necessary for achieving normal size and ploidy. In the second group of patients treated by BU these changes were absent. For this reason, our findings are in keeping with the assumption that during IFN treatment, there is at least partial recovery and expansion of a putative normal (Ph1-) megakaryopoiesis. In conclusion, megakaryocyte morphology, i.e. normalization in size, is thought to be a useful indicator to evaluate the response to IFN in CML patients.

Adult↗
PubMed1996

Interactions between endogeneous lectins and fucosylated oligosaccharides in megakaryocyte-dependent fibroblast growth of the normal bone marrow.

In order to elucidate the involvement of adhesion mechanisms in the process of megakaryocyte-dependent fibroblast growth, we applied BSA-coupled polymers of glucose, galactose, fucose, mannose, and several lectins (AAA, LCA, LTA, UEA-I) to cocultures of CD61 -positive (CD61+)/MACS-enriched megakaryocytes and human bone marrow fibroblasts. Fibroblast monocultures served as controls. After 6 days, glucose, as well as galactose-treated cultures showed a significant reduction of fibroblast growth in cocultures and fibroblast monocultures. In contrast, application of mannose caused no reducing effect on fibroblast numbers. Administration of fucose, AAA, LTA or UEA-I revealed a strong impairment of fibroblast growth in the megakaryocyte-fibroblast cocultures. Adhesion experiments using MACS-enriched, fluorescein-labelled megakaryocytes cultured in the presence of carbohydrates and lectins on a near-confluent layer of fibroblasts were additionally performed. Following fucose-BSA, alpha Fuc-1,2Gal beta-HSA or UEA-I treatment a significant reduction of megakaryocyte adhesion to the fibroblast layer could be observed. In the case of AAA a weak impairment of megakaryocyte adhesion could be noticed. Selective pretreatment of either fibroblasts or megakaryocytes with fucose-BSA or alpha Fuc-1,2Gal beta-HSA was consistent with the finding of a prominent involvement of fucosylated residues located on megakaryocytes in this interaction. In conclusion, our studies are in keeping with the assumption that fucosylated and fucose-binding structures are playing a key role in adhesion mechanisms between megakaryocytes and fibroblasts and thus influence significantly the megakaryocyte-dependent growth of bone marrow fibroblasts.

Adult↗
PubMed1996

AIDS-related bone marrow lesions--myelodysplastic features or predominant inflammatory-reactive changes (HIV-myelopathy)? A comparative morphometric study by immunohistochemistry with special emphasis on apoptosis and PCNA-labeling.

There seems to be general agreement that AIDS-related bone marrow changes are consistent with myelodysplastic features. To re-evaluate this assumption more critically, a comparative study was performed on marrow smears and trephine biopsies in 20 patients presenting manifest stages of AIDS and in 30 patients with primary myelodysplastic syndromes (MDS). For an assessment of cytological atypias enzyme-(naphthol AS-D-chloroacetatesterase) and immuno-histochemical techniques including monoclonal antibodies directed against erythro-(Ret40f) and megakaryopoiesis (CD61), macrophages (PG-M1) and proliferating cell nuclear antigen-PCNA (PC10) were applied and staining results determined by morphometric analysis. The in situ end-labeling (ISEL) technique was used for the demonstration of cells undergoing apoptosis (programmed cell death). In the HIV-infected bone marrow the frequency of erythroid precursors and macrophages exceeded significantly the corresponding counts in MDS. In comparison with a control group, megakaryocytes were increased in both entities under study. However, MDS was characterized by a prevalence of atypical microforms. The small-sized megakaryocytes in MDS revealed striking abnormalities of nuclear-cytoplasmic organization. Severe defects of nuclear lobulation (pseudo-Pelger anomalies) of mature neutrophils or nuclear bridging of erythro-normoblasts were not conspicuous in AIDS. Whereas the incidence of apoptosis was significantly higher in MDS, no such differences could be found comparing the PCNA-labeling index of AIDS and MDS. On the other hand, both parameters were significantly increased in comparison with the controls. In the HIV-infected bone marrow alterations of the myeloid stroma were most prominently expressed. If well defined criteria for the diagnosis of (myelo-) dysplasia were applied, our findings in AIDS were not in keeping with the assumption of significant maturation defects comparable with MDS. Hence, bone marrow lessions accompanying AIDS should be separated from MDS and should be diagnosed as HIV-myelopathy.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Distribution of lectin binding sites in human bone marrow. Identification by use of an ultrastructural postembedding technique.

The purpose of this ultrastructural study was to detect various carbohydrate residues on mature elements of the major human haematopoietic cell lines (granulopoiesis, erythropoiesis and megakaryopoiesis), sinus endothelium and plasma cells under comparable experimental conditions. Marrow specimens were processed according to a modified postembedding technique with Unicryl as embedding resin. A broad panel of 10 digoxigenin (dig)-conjugated lectins was applied for staining and specificity was evaluated by incubation with their corresponding inhibitory sugars. Lectins under study were derived from Canavalia ensiformis (Con A), Triticum vulgare (WGA), Ulex europaeus-I (UEA-I), Baubinia purpurea (BPA), Erythrina cristagalli (ECA), Glycine max (SBA), Helix pomatia (HPA), Arachis hypogaea (PNA), Griffonia simplicifolia-I (GS-I) and its isotype GS-I-B4. As a common feature WGA was shown to be a prominent marker of cytoplasmic membranes, except for plasma cells. On the other hand, Con A turned out to be reactive with the nuclear envelopes in all haematopoietic cells and, additionally, exhibited a strong labelling of the rough endoplasmic reticulum in plasma cells. Granules of eosinophilic granulocytes revealed staining of varying intensity with all lectins; however, inhibition was mostly incomplete. Several lectins (WGA, Con A, UEA, BPA, ECA, SBA and PNA) disclosed a clear cut differentiation of at least two subpopulations of granules in polymorphonuclear leukocytes. UEA-I (H type 2 specific) exhibited a high affinity to cytoplasmic membranes of erythropoietic precursor cells. In keeping with the blood group of our patient (O Rh+) membranes of red blood cells were completely negative with those lectins that are known to exhibit a group A or B specificity (HPA, GS-I-B4). As a remarkable finding the luminal and abluminal surfaces of sinusoidal endothelium revealed a specific reaction with UEA-I. Carbohydrate binding sites on the surface of endothelial cells may play a pivotal role in several functional processes such as cellular adhesion, traffic of mature cell elements across the marrow blood barrier and "homing' of haematopoietic stem cells.

Bone Marrow↗
PubMed1996

An improved postembedding technique for ultrastructural studies of lectin binding sites in bone marrow: a critical evaluation.

Little is known about the ultrastructural localization of lectin binding sites in human bone marrow tissue. This is probably due to the lack of suitable methods yielding both satisfactory tissue preservation and optimal labelling results. For this reason, we developed a modified postembedding technique for electron-microscopic studies of the glycosylation pattern of haematopoietic cells. Fixation with a 2.5% glutardialdehyde solution was shown to be an important prerequisite and could be even improved by postfixation with tannic acid and uranyl acetate. In particular, embedding with the acrylic resin UnicrylR (Bioacryl) resulted in an optimal ultrastructural preservation of bone marrow tissue. Employment of this hydrophilic resin in combination with a two-step labelling method which included digoxigenin-conjugated Concanavalin A (Con A) followed by ultrasmall anti-digoxigenin-gold and silver amplification, delivered a highly specific staining pattern. Our results with this lectin in different bone marrow cells revealed nuclear and cytoplasmic membranes, rough endoplasmic reticulum as well as granules to display reactivity of varying intensity. These findings underline the validity of our method, for they confirm and extend formerly reported histochemical and biochemical evaluations on the cellular binding sites of Con A.

Binding Sites↗
PubMed1996

Effects of interferon treatment on the macrophage population in the bone marrow of patients with Ph1+-CML.

In Ph1+-CML the abnormal function of bone marrow stroma was related to the presence of clonally transformed macrophages (MAs). Moreover, previous in vitro studies revealed that activation (phagocytosis, cytotoxicity) of MAs was associated with a pronounced increase in alpha-D-galactosyl residues on their membranes. Stimulation of this cell population has been shown to be easily accomplished by interferon (IFN) treatment. The latter caused an enhanced expression of binding sites for the lectin Griffonia simplicifolia isotype I-B4 (GSA-I), specific for this carbohydrate moiety. The present immuno- and lectinhistochemical study was designed to quantify MA subsets of the bone marrow in patients with Ph1+-CML under IFN therapy. For comparison a control group with monotherapy by busulfan (BU) was included. Identification of the total MA population was carried out by a monoclonal antibody against CD68 (PG-M1) and for the characterization of its activated fraction, the lectin GSA-I was employed. In both therapeutic groups morphometric analysis revealed a conspicuous increase in PG-M1-positive MAs in sequential trephine biopsies. However, following IFN therapy the relative amount of the GSA-I fraction was maintained or even increased and accompanied by enhanced apoptosis. On the other hand, BU generated a significant reduction of this subpopulation and the number of apoptotic cells as well. This finding is probably related to the immunomodulatory activity of IFN associated with MA activation and secretion of biogenic mediators. These are thought to belong partly to the so-called tumor necrosis factor superfamily, which is known to stimulate programmed cell death (apoptosis).

Adolescent↗
PubMed1995

Secretion of cytokines (interleukins-1 alpha, -3, and -6 and granulocyte-macrophage colony-stimulating factor) by normal human bone marrow megakaryocytes.

The effects of cytokine stimulation [recombinant human interleukin (rhIL)-1 alpha, rhIL-3, rhIL-6, rhIL-11, and rh granulocyte-macrophage colony-stimulating factor (GM-CSF)] on the secretory activity of normal human megakaryocytes were studied by means of the reverse hemolytic plaque assay (RHPA) in enriched cell preparations. This test facilitates an extremely sensitive determination of cytokine secretion at the single-cell level, together with the clear-cut identification of each immunostained (CD61) secretory active megakaryocyte. Moreover, the reverse transcriptase-polymerase chain reaction (RT-PCR) was used to investigate the expression of IL-6, IL-6 receptor (IL-6R), IL-9, IL-10, IL-12, and IL-13 mRNA in highly concentrated megakaryocyte preparations. In comparison with the spontaneous secretion rate, stimulation with rhIL-1 alpha, rhIL-6, and rhGM-CSF failed to induce a significant increase in the release of cytokines by CD61+ cells. On the other hand, both rhIL-3 and, in a less pronounced way, rhIL-11 exerted a marked effect on IL-6 secretion. Additionally, after stimulation with rhIL-3, a significant enhancement of the secretion of IL-3 and GM-CSF, but not of IL-1 alpha, could be observed. Using the RT-PCR, a significant induction of IL-6 expression could be appreciated in the enriched megakaryocyte population (60% to 80%) stimulated with rhIL-3. The results of this study provide persuasive evidence that a number of cytokines are synthesized and secreted by human megakaryocytes and not only by hematopoietic stroma cells. These data suggest the existence of autocrine and paracrine mechanisms that may influence maturation and differentiation of megakaryocytes as well as act on various stroma cells to sustain an appropriate hematopoietic micro-environment.

Base Sequence↗
PubMed1995

Clinical and histological features retain their prognostic impact under interferon therapy of CML: a pilot study.

In 55 patients with Ph1+ CML under interferon (IFN) monotherapy, an immunohistochemical and morphometric study on pretreatment bone marrow biopsies was performed to evaluate the prognostic impact of clinical as well as histological disease features. For identification of megakaryocytes we used the PAS stain and CD61 to calculate the subfraction of precursors (pro- and megakaryoblasts). Demonstration of macrophages and their different subsets was carried out by PG-M1 (CD68) and the GSA-1 lectin. The erythroid precursors were stained by Ret40f (anti-glycophorin C). Density of argyrophilic (reticulin plus collagen) fibers was determined by applying Gomori's silver impregnation method. Clinical variables like state of hematological response to IFN administration, age, spleen and liver size, myeloblasts plus promyelocytes, basophils as well as basophils and eosinophils exerted a predictive capacity by univariate statistical analysis. However, when entering these factors into previously published risk models, i.e., the so-called Sokal score and its modifications, to assess subgroups with different survival patterns or relative risk groups, a clear-cut discrimination was not feasible. Bone marrow features of prognostic value consisted of megakaryocytes and their precursors, fibers, and pro- and erythroblasts. Only when including histological variables into a formerly reported Cox model, could a significant separation of patients into the different categories or relative risk groups be computated. In conclusion, the present data emphasize the prognostic impact of histological parameters to be considered in all clinical trials on CML.

Adult↗
PubMed1995

The impact of interferon versus busulfan therapy on the reticulin stain-measured fibrosis in CML--a comparative morphometric study on sequential trephine biopsies.

To evaluate treatment-related changes of the reticulin stain-measured fibrosis in Ph(1+)-CML, a clinicopathological study was performed on sequential trephine biopsies of the bone marrow following either interferon (IFN) or busulfan (BU) monotherapy. Using the monoclonal antibody CD61 for the identification of megakaryopoiesis and Gomori's silver impregnation method, number of megakaryocytes and density of argyrophilic (reticulin and collagen) fibers were determined by morphometry. We studied specimens from 26 patients with IFN-alpha 2b (including nine patients with additional IFN gamma) therapy and from 23 patients who had received BU. In both groups, repeated bone marrow biopsies (total 125) revealed a significant increase in the fiber content, as well as in the number of megakaryocytes during treatment. To assess the dynamics of myelofibrosis more precisely, computation of differences in the degree of fiber density between the first and last examination was carried out. Regarding the considerable variations in the biopsy intervals, a so-called myelofibrosis progression index (MPI) was calculated. Following this rationale, we were able to demonstrate that, in comparison to the BU-group, speed of progression of bone marrow fibrosis was significantly increased in CML patients treated with IFN. Preliminary statistical analysis indicated a relationship between myelofibrosis on admission, which was always associated with increased growth of megakaryocytes, and the MPI with survival. Even when these parameters were regarded, prognosis was significantly more favorable in the IFN-treated patients. The failure of IFN and BU to inhibit the evolution of myelofibrosis may be related to several conversely acting pathomechanisms. Among others, the inability of both therapeutic agents to reduce the number of megakaryocytes more effectively should be taken into consideration.

Adolescent↗
PubMed1995

[Hematopoietic stem cells of the human. Function and morphology].

Pluripotential haematopoietic stem cells and their progeny, the so-called committed precursor cells, i.e., progenitor cells which are already lineage-restricted, may be identified by the membrane-bound expression of CD34. In accordance with this peculiar property it became possible to enrich and characterize primitive precursor cells by using different methods of cell separation techniques, which involved fluorescence staining or ferro-magnetic particles bound to CD34 antibodies. Recently conducted studies demonstrate that CD34-positive (CD34+) stem cells of the peripheral blood represent a relatively uniform cell population with almost round nuclei, a finely dispersed chromatin pattern and a small portion of weakly basophilic cytoplasm. From the cytological viewpoint they resemble so-called large stimulated lymphocytes (virocytes). Ultrastructural studies are compatible with a paucity of organelles and a lymphoid character of these progenitors. In comparison, the stem cell population, derived from the bone marrow consists of more heterogeneous elements. These are generally larger and reveal an admixture of fairly immature as well as more differentiated cells, sharing bean-shaped or indented nuclei with prominent nucleoli and a more extended cytoplasm. CD34+ progenitors from the peripheral blood and those from the bone marrow display a co-expression of CD43 (MT1) and CD45 (LCA). Furthermore, different subpopulations exhibit--dependent on their origin (blood/bone marrow) and to a various extent--lineage-restricted markers like CD33, CD38, CD61, CD20, CD11a/c, glycophorin C und CD15 (LeuM1). The recently developed immuno- and ferromagnetic enrichment methods for CD34+ progenitor cells are considered innovative tools for modern oncology. These techniques play an important role in the treatment of haematological malignancies and advanced tumours in the context of autologous and, although so far rarely applied, heterologous stem cell transplantation procedures.

Antigens, CD↗
PubMed1995

[Differential "lymphoid cell infiltrates" diagnosis in bone marrow].

The purpose of this study was to provide criteria for the differentiation of reactive lymphoid hyperplasia (RLH) and focal involvement of the bone marrow by malignant lymphoma (ML). Using trephine bone-marrow biopsy specimens embedded in paraffin wax and unequivocally established samples with ML for comparison, all patients with questionable lymphoid or lymphohistiocytic marrow aggregates were re-examined, together with obviously reactive lesions. Following this procedure, a number of characteristics were found that differed in validity with regard to diagnosis. In addition to cytology, which is preferably assessed in Giemsa-stained specimens and evaluated by the Kiel classification, histotopography, fiber content, and immunohistochemical reactions are the most valuable tools for differential diagnosis. RLH is consistent with a central-perivascular localization, a distinctive border and the presence of germinal centers, no or only minimal reticulin fibrosis and a polyclonal reaction pattern with a mixed population of B- and T-lymphocytes, following staining with appropriate antibodies. In uncertain cases (i.e., extensive lymphoproliferations in HIV-myelopathy) the results of immunohistochemical staining are of definite importance for the diagnostic evaluation of these lesions.

Biopsy↗