[Neuroendocrine neoplasms of the breast]. / Neuroendokrine Neoplasien der Mamma.

Neuroendocrine neoplasms (NEN) of the breast are specific tumor entities. According to the literature up to 5% of breast neoplasms are malignant epithelial neoplasms of the breast. They are defined by a neuroendocrine (NE) architecture and cytology combined with an expression of the neuroendocrine vesicle markers chromogranin A and/or synaptophysin. The diagnosis is supplemented by the receptor status and the proliferative activity. According to the World Health Organization (WHO) classification of 2012 the following groups of NEN are distinguished: (1) invasive breast carcinoma with NE differentiation, (2) well-differentiated neuroendocrine tumor (NET) and (3) poorly differentiated small cell carcinoma (NEC). This review article focuses on (1) the definition and basic principles of diagnostics, (2) the history, nomenclature and WHO classification from 2003 and 2012, (3) the frequency of breast NEN, (4) the hereditary background and functional activity, (5) the expression of receptors and (6) the possible clinical implications. In addition, the first results of a retrospective single center study (n = 465 patients with breast cancer over a time period of 4 years) on the frequency of NEN of the breast at the Breast Center of the University Hospital Düsseldorf are presented. In this study a frequency of 4.5% of NEN was found based on a diagnostic cut-off of > 50% Chromogranin A and/or synaptophysin positive tumor cells.

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.

Relevance and dynamics of myelofibrosis regarding hematopoietic reconstitution after allogeneic bone marrow transplantation in chronic myelogenous leukemia--a single center experience on 160 patients.

A retrospective single center study was performed on 516 trephine biopsies derived from 160 patients with stable phase Ph+-CML and allogeneic BMT. Following morphometric quantification of reticulin-collagen fibers we tried to elucidate (1) the dynamics of bone marrow fibrosis in the post-transplant period; and (2) the influence of manifest myelofibrosis on relevant engraftment parameters. An evaluation of fiber density at standardized endpoints after BMT was carried out on a selected cohort of 124 patients (399 biopsy specimens). A manifest myelofibrosis (more than a three-fold increase compared to the normal fiber content) before BMT was found in 26% of our patients. Concentrating on bone marrow areas with reconstituting hematopoiesis, several findings emerged. Pretransplant myelofibrosis was associated with an initial regression following BMT, but insidiously recurred in the areas of regenerating hematopoiesis or developed in a few patients without increased pregraft fibers during the post-transplant period (mean observation time more than 4 months). Severe acute GVHD (grades III and IV) was significantly correlated with a greater amount of reticulin fibers in the early post-transplant period (9 to 30 days after BMT). Regarding engraftment parameters, a significant delay was detectable in the time to achieve transfusion independence for the patients with manifest myelofibrosis compared to those without pre-transplant fiber increase.

Immunoreactivity of Thomsen-Friedenreich (TF) antigen in human neoplasms: the importance of carrier-specific glycotope expression on MUC1.

On the basis of their known fine specificities we evaluated the immunohistochemical marker qualities of two monoclonal antibodies (mabs) defining the tumor-associated TF disaccharide Gal beta 1-3 GalNAc. This antigen is expressed in certain tumors in correlation with prognosis and metastasis. The reactivity of one of these mabs (A78-G/A7) depends on clustered TF disaccharides (glycosylation at vicinal Ser/Thr positions) while the other--mab BW835--has been characterized to bind specifically to TF disaccharide linked to a motif within the MUC1 repeat. Therefore, mab BW835 represents an interesting tool for the identification of tumor-associated glycoforms of MUC1, which are involved in tumor progression and metastasis, but also in the recognition of tumor cells by cytotoxic T cells. As references the TF-binding lectins from peanut (PNA) and Artocarpus integrifolia (jacalin) were applied. The binding patterns of these immunoreagents were strikingly distinct. Mab BW835 showed a significantly stronger reactivity than mab A78-G/A7, especially in gastric, mammary, pancreatic, thyreoideal, renal and bladder carcinomas. PNA and jacalin receptors exhibited an expression in the majority of all cancer types, with the exception of seminoma and glioblastoma/sarcoma. These results can be explained by the broader fine specificities of the lectins. Furthermore, a strong expression of MUC1-bound TF antigen is indicated by the staining pattern of mab BW835. The marker qualities of both antigens, TF and MUC1, are combined in the binding specificity of BW835, and hence this antibody may have a high impact for the immunodetection of these tumor-associated antigens.

Focal lymphoid aggregates (nodules) in bone marrow biopsies: differentiation between benign hyperplasia and malignant lymphoma--a practical guideline.

AIMS: To provide practical guidelines for the differentiation between benign and malignant focal lymphoid aggregates (lymphoid nodules) in routinely referred bone marrow trephine biopsies, using a synoptic approach including clinical data and histological workup. METHODS: For easy identification of very small lymphoid infiltrates the chloroacetate esterase stain was applied as a screening procedure. This allowed the identification of 491 formalin fixed, paraffin wax embedded specimens with one or more lymphoid nodules. Examination of lymphoid infiltrates included such variables as histotopography, demarcation, cytology, reticulin fibres, and immunohistochemistry with a set of monoclonal antibodies (CD20, CD45R, CD45R0, CD3, CD43). Evaluation of clinical and morphological data was carried out independently. In case of malignant lymphomas, a correlation with corresponding lymph node findings was made. RESULTS: 352 patients had benign focal lymphoid aggregates usually associated with systemic autoimmune diseases, chronic myeloproliferative disorders, toxic myelopathy, and viral infections. Discrete nodular infiltrates of (small cell) malignant lymphomas (n = 93) simulating benign hyperplasia were found in chronic lymphocytic leukaemia, germinal centre cell lymphomas (CB-CC), and lymphoplasmacytic/cytoid lymphomas (LPI). In addition to immunoreactivity, certain histological variables proved distinctive. These were: (1) histotopography, that is, localisation of the lymphoid aggregates within the bone marrow space; (2) relation to the surrounding tissue: margination or interstitial spillage of lymphoid cells; and (3) increase in reticulin fibres. CONCLUSIONS: A combined diagnostic procedure identifying several distinctive features, in particular histotopography and immunohistochemistry, provides a most promising way of discriminating reactive from neoplastic lymphoid nodules in the bone marrow.

Characterization of CD34+ human hemopoietic progenitor cells from the peripheral blood: enzyme-, carbohydrate- and immunocytochemistry, morphometry, and ultrastructure.

Following an immunomagnetic isolation and enrichment procedure, CD34+ cells were harvested from the peripheral blood of about 50 healthy donors. A battery of cytochemical staining reactions, monoclonal and carbohydrate-specific antibodies, proliferation markers and lectins was applied on smears and sections from paraffin-embedded pellets. Additionally, a morphometric analysis and ultrastructural investigation was carried out. More than 95% of the total yield of progenitor cells expressed CD34 and CD43 (MT1) and of these about 90% CD45 (LCA) and 25% CD45A (MT2). The CD34+/CD45RA-population was thought to represent very primitive, probably not lineage-restricted stem cells. On the other hand, reactivity with ANAE, CD11c, CD15, CD20, Ret40f, KiM1P, and CD61 (ranging between 1 to 20%) was considered to indicate a transition into more differentiated elements of hemopoiesis. The failure to detect any staining with proliferation markers (Ki-67/MIB 1, PCNA, KiS1) was in keeping with a quiescent status. Carbohydrate antigens revealed a pattern which underlines the fact that the CD34 and CD43 antigens belong to the family of heavily O-glycosylated sialomucins. Blood group antigens which are located at the peripheral regions of mucin-oligosaccharides (H type 2, Lewis, Lewis) could be demonstrated, but not A, B, Sialyl-Lewis and Lewis. Morphometric analysis revealed that CD34+ progenitors were larger than small lymphocytes. Electron microscopy showed a relatively primitive cytoplasmic organization and numerous tiny magnetic beads clustered at the plasma membrane.

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.

Bone marrow features and clinical findings in chronic myeloid leukemia--a comparative, multicenter, immunohistological and morphometric study on 614 patients.

A multicenter, immunohistochemical and morphometric study was performed on diagnostic pretreatment bone marrow biopsies in 614 adult patients with Ph1+ chronic myeloid leukemia (CML) to compare histological features with clinical findings. For identification of megakaryopoiesis we used the monoclonal antibody CD61 and additionally the PAS reaction to determine the subfraction of atypical micromegakaryocytes and precursors. Labelling of erythroid precursors was carried out by a monoclonal antibody directed against glycophorin C. In order to selectively stain macrophages and their activated subset we applied CD68 and the GSA-I lectin. Density of argyrophilic fibers (reticulin plus collagen) was measured following Gomori's silver impregnation method. In accordance with laboratory data morphological variables revealed a comparable amount of congruence in the various groups of CML patients derived from different sources. In about 26% of patients early (reticulin) to advanced (collagen) fibrosis was detectable. Significant correlations were calculated between the extent of myelofibrosis with splenomegaly, anemia and increasing numbers of erythroblasts and myeloblasts in the peripheral blood count. These features were assumed to indicate more advanced stages of the disease process with ensuing transition into myeloid metaplasia and consequently were associated with an unfavorable prognosis. Significant relationships were revealed between the number of CD61+ megakaryocytes and more important, also their precursor fraction with the degree of fibrosis. This result extends previous experimental findings regarding the impact of immature elements of this cell lineage for the generation of myelofibrosis. The significant association of erythroid precursors with the number of mature (resident) macrophages including their activated GSA-I subset may shed some light on their functional involvement in iron turnover and hemoglobin synthesis. A modified histological classification of predominant bone marrow features is introduced. This simplified synthesis staging system (Cologne Classification) is not only associated with certain sets of laboratory data, but also with different survival patterns.

Tenascin expression in gastric cancer with special emphasis on the WHO-, Lauren-, and Goseki-classifications.

Ample evidence has been provided concerning the presence of tenascin in various histological subtypes of gastric cancer. However, conflict and discussion still persist regarding the correlation with different classification systems and prognostic impact. Therefore, we studied 203 adenocarcinomas of the stomach with special emphasis to the WHO-classification, Lauren's and Goseki's subtypes as well. The immunohistochemical ABC-method was applied using a monoclonal anti-human-tenascin antibody. 30% of all tumours showed a distinct staining reaction. Tubulo-papillary carcinomas (WHO) revealed a significantly stronger reactivity than signet-ring subtypes. Adenocarcinomas of intestinal type (Lauren) were significantly more positive than the diffuse types. Mucin-poor tumours (Goseki I+III) stained positive in a much higher degree compared to mucin-rich subtypes (Goseki II+IV). However, no correlation could been demonstrated regarding TNM-stage or prognosis.

Expression of mucin-associated carbohydrate core antigens in esophageal squamous cell carcinomas.

In contrast to gastrointestinal cancer, where a correlation between the expression of different mucin-associated core antigens with clinico-pathological parameters and survival probability, has been established, little is known about their importance in esophageal cancer. Therefore, we characterized esophageal squamous cell carcinomas from 84 patients immunohistochemically by applying monoclonal antibodies (mabs) directed against the Thomsen-Friedenreich (TF) antigen MUC1-bound TF antigen and sialyl-Tn. TF was observed in about 40% of the cases and MUC1-TF epitope in about 75%. Sialyl-Tn was detectable in about half of the carcinomas under study. None of these mabs showed any correlation between binding pattern and clinico-pathological variables, such as TNM stage, lymph node metastasis or grading. However, a strong expression of MUC1-TF epitope as well as sialyl-Tn antigen predicted a poor survival probability. In conclusion, it is suggested that mucin-associated carbohydrate core antigens are involved in the biology and clinical course of esophageal squamous carcinomas.

Histological grading in gastric cancer by Goseki classification: correlation with histopathological subtypes and prognosis.

BACKGROUND: Many different classification systems have been proposed for the histological classification and grading of gastric cancer. In 1992 Goseki described a novel classification system for gastric cancer based on tubular differentiation and mucus in the cytoplasm. The aim of the study was to compare the Goseki classification with the currently used classification systems and to define the prognostic significance of the Goseki classification system. PATIENTS AND METHODS: The present study analyzed material from 200 gastric carcinoma patients who underwent gastrectomy with curative intention. All specimens were categorized to UICC-classification, WHO-classification, Laurén classification, tumor differentiation and Goseki classification. The median follow-up for surviving patients was 3.75 years (range, 0.14-11.52). RESULTS: According to the Goseki classification 32% of patients were classified as group I, 11.5% as group II, 9.5% as group III and 48% as group IV. The Goseki classification was found to correlate with the WHO and Lauren classification as well as with conventional grading. Goseki classification as well as tumor differentiation, Lauren and WHO classification did not have prognostic value for survival. Only the UICC system presented as an independent prognostic factor in multivariate analysis (p < 0.000001). CONCLUSION: In our series Goseki classification correlated with conventional classification systems, but not with survival.

Foreign-body reaction and the course of osteolysis after polyglycolide implants for fracture fixation: experimental study in sheep.

Foreign-body reaction to polyglycolide (PGA) implants has been described in man. Many animal experiments have verified the mechanical properties of fixation devices made from PGA, but a significant foreign-body reaction has not been described. We studied the effect of PGA rods in 12 sheep with standardised osteochondral fractures of the medial femoral condyle fixed with uncoloured, self-reinforced PGA rods (Biofix). Radiographs were taken at intervals ranging from two weeks to two years, and the sheep were killed at intervals ranging from six to 24 months. All knees were examined histologically. Eleven of the 12 fractures healed radiologically and histologically. Moderate to severe osteolysis was seen at four to six weeks with maximum changes at 12 weeks in ten animals. Six knees showed fistula-like connections between the implant site and the joint space. Three developed synovitis, one with inflammatory changes involving the whole cartilage and one with destruction of the medial condyle. Although in our study osteochondral fractures fixed with PGA rods healed reliably, there were frequent, significant foreign-body reactions. Caution is needed when considering the use of PGA fixation devices in vulnerable regions such as the knee.

Rounded atelectasis in a patient with history of asbestos exposure. A case report.

We report a case of a 68-year-old patient with a history of chronic asbestos exposure and a lung tumour, highly suspicious for bronchial carcinoma. The patient underwent left lower lobectomy and histology showed the rare diagnosis of rounded atelectasis. Rounded atelectasis is an important differential diagnosis to bronchial carcinoma.

Lewis(y) antigen (CD174) and apoptosis in gastric and colorectal carcinomas: correlations with clinical and prognostic parameters.

Lewis(y) (Le(y)), also designated CD174, represents a carbohydrate blood group antigen which is strongly expressed in neoplastic gastrointestinal tissues. Previous reports indicated an association between Le(y) expression and apoptosis. Therefore, we tried to elucidate its clinicopathological relevance in a series of 160 gastric and 215 colorectal carcinomas by immunohistochemical detection of Le(y) and visualization of apoptotic cells applying the in-situ-end labelling (ISEL) method, followed by semiquantitative scoring of the specimens. In both gastric as well as colorectal carcinomas, between 40 and 50% of the cases were Le(y) reactive. Signet-ring cell carcinomas of the stomach exhibited a significantly stronger Le(y) expression compared to other tumor types. In colorectal cancers, Le(y) was associated with increased tumor staging, showing the strongest positivity in stage IV. Further correlations with clinicopathological variables or prognosis were not observed. On the other hand, the amount of apoptotic cells was significantly reduced in mucinous adenocarcinomas of the colorectum compared to non-mucinous carcinomas. Scoring of apoptotic cells did not result in any other clinicopathologically relevant correlations. In addition, a significant association between Le(y) antigen expression and apoptosis score could not be established. Therefore, the hypothesis of a functional relationship between these two aspects of gastrointestinal tumor biology is not confirmed by our data.

Nephrogenic adenoma: A rare bladder tumor in children.

OBJECTIVE: Nephrogenic adenomas of the urinary bladder are rare benign tumors in children. The purpose of our study was to obtain information about the sex distribution, presenting symptoms, intravesical locations, therapy and recurrence rates in pediatric nephrogenic adenomas. PATIENTS AND METHODS: The records of 3 children with nephrogenic adenoma of the urinary bladder diagnosed between 1990 and 1997 were reviewed to evaluate the initial symptomatology, diagnostic examinations and findings, therapeutic procedures and clinical outcome and recurrence rates. Furthermore our data are compared to the findings of all children reported in the literature. RESULTS: Including the 3 cases reported by us, the data on 18 children with nephrogenic adenoma of the bladder could be analyzed. There was a significant predominance of girls compared to boys (5:1); the medical history in all cases was remarkable for previous bladder surgery 3 months to 7 years prior to tumor diagnosis. Most children presented with unspecific symptoms of gross hematuria, dysuria and bladder instability and in all cases the final diagnosis was established after cystoscopy and histopathologic review of a tumor biopsy specimen. Therapy consisted of transurethral resection in 15 cases, partial cystectomy and open excision in 2 and 1 case, respectively. Tumor recurrence developed in 80% of the children with a latency period of 4 years. CONCLUSIONS: Nephrogenic adenomas represent an epithelial response of the urothelium to chronic inflammation or previous trauma resulting in urothelial metaplasia and the development of papillary lesions. Current treatment of choice consists of transurethral resection and fulguration of the base of the tumor and periodic cystoscopy.

[Highly differentiated squamous epithelial carcinoma as a late complication of post-traumatic osteomyelitis]. / Hochdifferenziertes Plattenepithelkarzinom als Spätkomplikation einer posttraumatischen Osteomyelitis.

Squamous cell carcinoma as a late complication of chronic osteomyelitis is a well known phenomenon in traumatology, often occurring as a consequence of bone fractures. The majority of cases are observed in men between 50 and 60 years of age. The time from onset of inflammatory bone disease to malignant transformation differs but usually takes 30 years. In general, prognosis is thought to be favorable when adequate surgical therapy is carried out. Nowadays, it is important to recall this condition, because it has become rare. The cases reported here illustrate the difficulties that may be encountered in diagnosing malignant transformation, especially in lesions that develop in deep tissue layers and which may be responsible for various biopsies failing to reveal the true pathology.

Incidence of apoptosis in HIV-myelopathy, myelodysplastic syndromes and non-specific inflammatory lesions of the bone marrow.

Myelodysplastic syndromes, AIDS-related myelopathy and non-specific inflammatory reactions (mostly rheumatoid myelitis) are characterized by normo- to hypercellular bone marrow, but frequently display cytopenias in the peripheral blood. In the current study we have addressed the question whether this situation reflects an increased programmed cell death in haemopoiesis. For this purpose, the in situ end-labelling technique was applied to formalin-fixed and paraffin-embedded trephine biopsies derived from patients and a control group without any haematological disorder. Results were evaluated by morphometry. Significantly more apoptotic cell death was observed in the haemopoietic marrow of patients with either disease. Using double-immunohistochemistry with the monoclonal antibody PG-MI (CD68), we were able to demonstrate that approximately one third of the apoptotic cells were ingested by macrophages. Our findings are in keeping with previously published data that postulated increased frequencies of macrophages in these disorders as well as raised serum levels of TNF-alpha.

Apoptosis (programmed cell death) in idiopathic (primary) osteo-/myelofibrosis: naked nuclei in megakaryopoiesis reveal features of para-apoptosis.

There is general agreement that apoptosis (programmed/physiological cell death) plays an important role in regulating normal hematopoiesis and that so-called naked nuclei (NN) present end stages of megakaryopoiesis. Using in situ end-labeling techniques (ISEL), a morphometric analysis was performed on bone marrow trephine biopsies repeatedly derived from patients with idiopathic (primary) osteo-/myelofibrosis (IMF). The purpose of this study was to quantify apoptosis and to elucidate its relationship with NN of megakaryopoiesis. Moreover, evolution of this phenomenon during progression of myelofibrosis (assessed by morphometry of silver-stained sequential biopsies) and its predictive value were investigated. In IMF, morphometric measurements revealed a rate of ISEL-positive cells that was significantly higher than previously published data on the normal bone marrow and in patients with acute myeloblastic leukemia, but lower than in the myelodysplastic syndromes. However, NN with their tightly packed (nuclear) lobules and condensed chromatin were not reactive. Statistical evaluation failed to show a significant correlation between incidence of apoptotic cells and fiber density or an increase in this feature associated with progression of fibro-osteosclerotic marrow changes and prognosis. The failure of NN to react in ISEL implicates an absence of DNA fragmentation characteristic of apoptosis. For this reason our findings are in keeping with the assumption that NN are compatible with para-apoptosis.

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.