[Neurinoma of the hard palate in an 11-year-old girl. Case report]

BACKGROUND

Neurinomas or schwannomas are benign, encapsulated growing tumors of the Schwann cells of the nerve sheets; 25-45% are located in the head and neck region. They are found rarely in the oral cavity. Most of the intraoral schwannomas are located on the tongue. Other less common locations are the buccal mucosa, palate, floor of the mouth, gingiva and lips. The therapy of choice is complete surgical excision.

CASE REPORT

An 11-year-old girl presented with a 3-month history of painless swelling of the hard palate. CT scan showed a right palatinal mass of 2 cm, reaching into the right maxillary sinus. After complete surgical excision the histological findings showed a neurinoma (Antoni type A). During a 2-year follow-up, there were no signs of recurrence. Because of the benign tumor type we considered the young patient to be healed.

Trisomy 8 in prefibrotic early stages of chronic idiopathic myelofibrosis: a fluorescence in situ study of bone marrow biopsies

Repeatedly performed bone marrow biopsies were studied in 30 patients with chronic idiopathic myelofibrosis (CIMF) by fluorescence in situ hybridization to detect and quantify trisomy 8 anomaly during the evolution of disease. For the establishment of threshold values we used negative and positive control specimens. At least 500 cells were evaluated in each specimen and only nuclei with three distinctive signals were regarded as positive. According to the controls, 27 patients revealed false-positive signals ranging from 0 to 1.2% (0.88 +/- 1.12). On the other hand, 3 patients showed an incidence of more than 6.5% (up to 10.1%) in the initial prefibrotic as well as advanced fibro-osteosclerotic stages of CIMF. In conclusion, trisomy 8 has been demonstrated already in the prodromal stages of CIMF and therefore is not limited to classical fibro-osteosclerotic manifestations.

Masaoka staging is of prognostic relevance in type B3 / C thymomas

BACKGROUND

The purpose of this study was to correlate the Ki67 labelling index (LI) with the Masaoka classification and the new WHO-classification in type B3 / C thymomas.

PATIENTS AND METHODS

Fourteen patients with type B3 / C thymomas were evaluated, and archived specimens were histologically reclassified according to Masaoka staging, the new WHO classification and the Ki-67 LI in a retrospective analysis.

RESULTS

Four patients presented with Masaoka stage II disease (all WHO-type B3), 1 patient had stage III (WHO-type C), 6 stage IVa (3 WHO-type B3 and 3 WHO-type C), and another 3 patients stage IVb (all WHO-type C). The statistical analysis revealed a significant correlation between Masaoka staging and Ki-67 LI (II, III vs. IV; p = 0.007). As well, WHO-classification correlated significantly with Ki-67 LI (B3 vs. C; p = 0.015). Masaoka staging (II, III vs. IV) correlated significantly with survival status (p = 0.0237) in patients with type B3 / C thymoma whereas WHO-classification did not (p = 0.3266). Between survivors and non-survivors there was no statistically significant correlation concerning Ki-67 LI (p = 0.075).

CONCLUSION

Our study indicated that the Masaoka staging system is of prognostic relevance in type B3 / C thymomas.

Computed-tomography-guided percutaneous core needle biopsies of suspected malignant lymphomas: impact of biopsy, lesion, and patient parameters on diagnostic yield

PURPOSE

To investigate the diagnostic yield of core needle biopsy in patients with malignant lymphoma.

MATERIAL AND METHODS

Computed-tomography-guided core needle biopsies in patients with malignant lymphoma performed in the period 1996 to 2001 were evaluated retrospectively. A biopsy was considered as "fully diagnostic" if a histological diagnosis, including the histologic subtype in the event of malignant lymphoma, was achieved and the clinical course and CT follow-up of at least 6 months confirmed the biopsy results. A biopsy was regarded as "partly diagnostic" if histological work-up defined malignant lymphoma but not the histological subtype, and if histological diagnosis bore therapeutic relevance. Diagnostic yield was correlated with features such as size of specimen, location and depth of the target lesion, and experience of the investigator.

RESULTS

45 biopsies were performed in 40 patients. With respect to definite histopathological diagnosis, 31 biopsies (68.9%) were diagnostic and 14 (31.1%) non-diagnostic. In 4 cases (8.8%), biopsies yielded partly diagnostic results, since therapy could be scheduled after biopsy without final sub-classification. Statistical analysis of biopsy parameters revealed that sample sizes were significantly larger in the diagnostic group.

CONCLUSION

CT-guided biopsy can be considered as an alternative for lymphoma diagnosis and should be the first interventional procedure. The most important parameter for diagnostic success is the size of the specimen.

Regeneration of heart muscle tissue: quantification of chimeric cardiomyocytes and endothelial cells following transplantation

Persuasive evidence has been recently provided that adult bone marrow (BM) cells exert greater plasticity than previously assumed. This review is focused on the quantification of mixed chimerism (mCh) in the hearts (cardiomyocytes and endothelial cells) of patients after orthotopic heart to heart transplantation (HHT) in comparison to full (unmanipulated) allogeneic BM and peripheral blood stem cell (PBSC) transplants. Following a sex-mismatched transplantation constellation heart muscle tissue obtained at autopsy was examined. Evaluation of mCh was most often performed by immunophenotyping combined with fluorescence in-situ hybridization (FISH) applying x- and y-chromosome-specific DNA probes. When comparing our data with the results of former studies that were regularly based on the detection of the y-chromosome alone, the quantity of chimeric cardiomyocytes after HHT ranged from 0% to 9%. On the other hand, after full BM transplantats (chimeric) cardiomyocytes of donor-type origin appeared at an incidence between 0.23% to 6.4%. These disturbing inconsistencies were assumed to be related to methodology: the restriction to the y-chromosome, disregard of the plane of section (detection sensitivity ranging between 35% and 67%) and state of tissue preservation (cadaver hearts). Therefore, when strictly applying dual color FISH and limiting the recognition of chimeric cardiomyocytes and endothelial cells to the presence of two distinctive signals detection sensitivity was significantly enhanced. Contrasting a total congruence with the genotyping in control specimens of normal cadaver hearts, a striking disparity in the extent of mCh was found depending on the different modes of transplantation. After allografting with PBSC a considerably low incidence (1.6%) of chimeric cardiomyocytes was determined contrasting with 5.3% of donor-derived cells after full BM transplants. Following HHT host-type endothelial cells (16.2%) of the intramural and subepicardial vessel walls were more often encountered than following BM and PBSC allografting. These findings are in keeping with the assumption of a sprouting and migration of vascular structures into the donor heart from the site of surgical aligment and injury between retained host and donor atrial walls. When considering the other methods of transplantation (BM, PBSC) the data on chimeric endothelial cells support the hypothesis of a common hemangioblast. Concerning the cardiomyocytes it seems most reasonable to assume that primitive mesenchymal stem cells of the BM play a pivotal role in the development of mCh. This phenomenon is more extensively expressed than previously expected and may be related to an enforced repair of the damaged myocardium during the post-transplant period as the sequel of myeloablative (cardiotoxic) conditioning.

Mixed chimerism of erythro- and megakaryopoiesis following allogeneic bone marrow transplantation

Until now, studies on mixed chimerism (MCh) after allogeneic bone marrow transplantation (BMT) have predominantly focused on the B- and T-lymphocyte population, but not on distinct myeloid cell lineages like nucleated erythroid precursors and megakaryocytes. To evaluate the lineage-restricted MCh more explicitly in 10 patients with chronic myelogenous leukemia (CML), a quantitative analysis was performed on bone marrow biopsies following a sex-mismatched host/donor constellation. Techniques included immunophenotyping (antiglycophorin C, CD61) for the identification of erythro- and megakaryopoiesis and a simultaneously conducted genotyping with x- and y-chromosome-specific DNA probes. Normal bone marrow and specimens taken before BMT served as controls. Contrasting a total gender-dependent sex-typing in the latter samples in the early and late posttransplant period (up to 586 days), 3-9% erythroid precursors and about 16% megakaryocytes revealed a host-type origin. This significantly higher number of host megakaryocytes is explained by their polyploidy generating an increased probability to detect positive signals at a certain section level of the corresponding biopsies. A striking conversion of MCh to a recipient cell type was found in leukemic relapse with a more than 90% host-derived erythroid and megakaryocytic cell population in 4 patients approximately 643 days after BMT.

Dynamics of lineage-restricted mixed chimerism following sex-mismatched allogeneic bone marrow transplantation

Scant knowledge is available about the dynamics of lineage-specific mixed chimerism (Ch) following bone marrow transplantation (BMT). This review is focused on findings derived from bone marrow (BM) biopsies in patients with chronic myeloid leukemia (CML) including a sex-mismatched host/donor constellation. Appropriate techniques involved immunophenotyping by monoclonal antibodies to identify the various cell lineages, dual color fluorescence in situ hybridization (FISH) with x- and y-chromosome-specific DNA-probes and a proper detection system for a simultaneous labeling of the bcr/abl locus. A significant degree of Ch with more than 20% host CD34+ progenitors was found in the early and late (up to 200 days after BMT) posttransplant period. However, only 10% of these cells harbored the bcr/abl translocation gene. This result fits well with corresponding molecular biological findings of so-called minimal residual disease. Conversion of Ch evolved during leukemic relapse with 90% host progenitors of which 50% revealed the bcr/abl locus. A Ch of nucleated erythroid percursors (5%) and CD68+ macrophages (8%) was expressed to a significantly lower degree. The slightly increased frequency found in CD61+ megakaryocytes (16%) was probably due to the polyploid state of these cells. Similar to the CD34+ progenitor cells abrupt changes from donor to host type was associated with an insidious transformation into recurrent leukemia. The CD34+ endothelial cells showed a minor degree of Ch, because donor-derived elements ranged from 18% to 25%. Leukemic relapse was characterized by an almost complete conversion of the endothelial cells to a host type. These findings point towards a CD34+ progenitor cell origin of the (leukemic) endothelial cell layer and suggests that their dysfunction may contribute to an expansion of the neoplastic clone.

[Hematopoietic stem cells and hematopoietic neoplasias]

Pluripotent hematopoietic stem cells have been defined as cells with extensive self-renewal capacity and lympho-hematopoietic differentiation potential. Clonal selection of a stem cell as a first step in the progression to neoplasia can be achieved by an alteration of this self-renewal potency. Our current understanding of the pathogenesis of the myeloproliferative disorders including acute myeloid leukemias, chronic myeloproliferative disorders (CMPD) and myelodysplastic syndromes (MDS), is based on the assumption that they represent a clonal disorder resulting from transformation of a hematopoietic stem cell. However, when performing methods for determining X-chromosome inactivation in female patients as a clonality marker, a significant minority of the patients with Philadelphia chromosome negative (Ph(-)) CMPD and MDS exhibit polyclonal proliferation. The implications of these results are not yet clarified and the lack of a proven target cell impairs the understanding of the underlying molecular defect. In this context, altered response to cytokine stimulation in vitro provides indirect information concerning molecular dysregulation. A subset of patients with MPD present with translocations that facilitate molecular investigation and clonality proof. They nearly always result in rearrangements of at least one transcription factor gene. Most of these fusion genes are constitutively active, sending out continuous proliferative and antiapoptotic signals or activate an overlapping set of signalling pathways. The classical example for a balanced translocation is the t(9;22) bcr-abl aberration in chronic myelogeneous leukemia. Many other karyotypic abnormalities have also been associated with CMPD and MDS and involve deletions of chromosomes 20q, 13q, 1q, 7q and 5q as well as trisomy of 8 and 9. Our increased understanding of the hematopoietic stem cell compartment and the molecular basis of regulation of its self-renewal and differentiation bears a direct impact on our understanding of leukemia evolution and progression.

[Extramedullary initial manifestations of acute myeloid leukemia (AML)]

Extramedullary myeloblastic tumors, so-called myelosarcomas (granulocytic sarcomas, chloromas) have been reported only sporadically in the pertinent literature which reflects their rather infrequent occurrence. These lesions may accompany the initial manifestation or signal relapse of acute myeloid leukemia (AML) or coincide with blastic transformation of a chronic myeloproliferative disorder. However, even more rarely, primary myelosarcomas may precede AML by months or years or may be associated with myelodysplastic syndromes (MDS) that never progress to manifest leukemia. In a retrospective evaluation a clinicopathological study on these latter two variants of isolated extramedullary manifestations of AML was performed to elucidate certain aspects of site involvement and histopathology by application of enzyme and immunohistochemistry. For this reason, we selected 6 patients presenting with a myelosarcoma in combination with MDS and 12 patients revealing only uncharacteristic reactive changes of the bone marrow. Of these patients 8 developed AML following an observation time of up to 2 years. Focal leukemic infiltrates were most often localized in the skin ( n=4), oral mucosa ( n=4), lymph nodes ( n=3), gastrointestinal tract ( n=3) or pleura and retroperitoneum ( n=3 each). Myelosarcomas were usually regarded by the clinicians as putative malignant lymphomas unless further evaluation, especially involving chloroacetate esterase reactions as well as immunostaining with a panel of antibodies reactive with lysozyme, myeloperoxidase, CD68, CD43, CD56, CD117 and CD34 proved their true nature. Although at that time bone marrow findings were inconclusive, a straightforward diagnosis was reached by considering the possibility of a (primary) myelosarcoma in these patients.

[Chimerism of cardiomyocytes and endothelial cells after allogeneic bone marrow transplantation in chronic myeloid leukemia. An autopsy study]

The results of a number of animal experimental studies are in keeping with the finding that hematopoietic progenitors can generate cardiomyocytes and endothelial cells. As a consequence innovative therapeutic strategies have been suggested to possibly ameliorate the outcome of coronary artery disease. However, there is no information available at present whether this pathomechanism is also effective in humans, in particular without prior ischemic lesion of the myocardium. Therefore an autopsy study was performed on cadaver hearts derived from five male patients with chronic myeloid leukemia who received full unmanipulated bone marrow grafts from female donors 21-631 days before death. The purpose of this investigation was to detect and quantify a putative chimerism of cardiomyocytes and endothelial cells (intramural and subepicardial vessels). Genotyping was carried out by applying X- or Y-chromosome-specific DNA probes (fluorescence in-situ hybridisation) on routinely formalin-fixed specimens of the myocardium. To test the sensitivity of our method, cadaver hearts from two males and two females without a history of transplantation served as controls. In contrast to a totally corresponding sex-matched genotyping in 780 cardiomyocytes and 155 endothelial cells of the control group, the five male patients with a previous transplantation revealed significantly different results. A mixed chimerism was identifiable in 57 out of 890 counted cardiomyocytes (6.4%) and in 19 out of 322 endothelial cells (5.8%). These findings support the assumption that in addition to endothelial cells there is also a cardiomyogenic potential of bone marrow stem cells which exists without prior (ischemic) damage to the heart. However, further investigations are necessary to identify, isolate and enrich the cardiomyocytic stem cells more specifically for future curative therapeutic options in patients with severe ischemic cardiomyopathy.

Preclinical evaluation of the antiproliferative potential of STI571 in Hodgkin's disease

STI571 is a selective tyrosine kinase inhibitor with proven therapeutic potential in malignancies expressing c-kit. A strong c-kit and stem cell factor expression was detected in the Hodgkin and Reed Sternberg cell line L1236, but not in 20 primary cases of classical Hodgkin's disease. Proliferation of L1236 cells was neither affected by addition of stem cell factor nor by neutralising anti-stem cell factor antibodies or STI571. Results suggest that patients with Hodgkin's disease may not benefit from therapy with STI571.

Oct-2 and Bob-1 deficiency in Hodgkin and Reed Sternberg cells

Hodgkin and Reed Sternberg (H-RS) cells represent the malignant cells in classical Hodgkin's disease. Although derived from germinal center B cells, they do not express surface immunoglobulin. This has been explained by the presence of crippling mutations within the immunoglobulin genes in numerous cases of Hodgkin's disease. As immunoglobulin gene expression in B cells requires an interaction between octamer sites and the transactivating factors Oct-2 and Bob-1, this study addresses the expression of the transcription factors Oct-2 and Bob-1 in H-RS cells. In Hodgkin's disease-derived cell lines, low levels of Oct-2 transcripts but no Oct-2 protein were detected. Transcripts of Bob-1, a B-cell-specific co-factor of Oct-2, could not be observed in these cell lines. Absence of Oct-2 and Bob-1 protein expression in primary H-RS cells was demonstrated by performing immunohistochemistry in 20 cases of classical Hodgkin's disease. H-RS cells stained negative for both proteins in all of the cases analyzed. In conclusion, absence of functional Oct-2 and Bob-1 cells represents a novel mechanism for immunoglobulin gene deregulation in H-RS cells. Lack of Oct-2 and Bob-1 points to a defect in transcription machinery in H-RS cells and is associated with lack of immunoglobulin gene expression in these cells.

Disseminated Neocosmospora vasinfecta infection in a patient with acute nonlymphocytic leukemia

We report Neocosmospora vasinfecta infection following chemotherapy for acute nonlymphocytic leukemia. N. vasinfecta, a plant pathogen, was identified by culture and genetic sequencing. Susceptibility testing revealed in vitro resistance for common antifungals.

Selectins (CD62L, CD62P) and megakaryocytic glycoproteins (CD41a, CD42b) mediate megakaryocyte-fibroblast interactions in human bone marrow

Previous in vitro studies are in keeping with the finding that isolated and enriched megakaryocytes attach to bone marrow fibroblasts and generate an increased growth of these cells. This process was assumed to depend on a close spatial relationship between both cell types which supports the paracrine effect of platelet-derived growth factor (PDGF) and transforming growth factor (TGF)-beta1. Moreover, adhesion molecules including beta1 integrin receptors and fucosylated structures were determined to play an important role in these complex interactions. However, up to now the influence of megakaryocyte expressed glycoproteins CD41a and CD42b in these processes was not investigated. In addition, the role of megakaryocytic CD62P and also of CD62L, both adhesion molecules of the selectin group, could also be of interest. Following isolation and enrichment of bone marrow megakaryocytes and fibroblasts, both cell populations were characterized regarding their expression of these factors by applying immunocytochemical techniques. Additionally, their influence on adhesion of megakaryocytes to fibroblasts as well as fibroblast growth was evaluated by comparative megakaryocyte-fibroblast co-cultures and inhibition studies using specific monoclonal antibodies (mabs). Fibroblast monocultures served as controls. In these experiments, selectin-specific antibodies significantly reduced megakaryocyte attachment to fibroblast feeder layers and fibroblast growth in the co-cultures. The effect of CD41a and CD42b specific antibodies was limited to megakaryocyte-dependent fibroblast growth. These results elucidate the involvement of the selectins CD62P and CD62L in the basal activation of megakaryocytes inducing their attachment to bone marrow fibroblasts. In contrast, the megakaryocyte glycoproteins CD41a and CD42b exert their effect on the megakaryocyte dependent fibroblast growth. Altogether, it is tempting to speculate that the various interactions of these mediators reflect certain steps in the complex pathomechanisms causing the evolution of (reactive) myelofibrosis in hematopoietic neoplasias accompanied by megakaryocytic proliferation.

Fatal thrombotic thrombocytopenic purpura as a rare complication following allogeneic stem cell transplantation

Thrombotic thrombocytopenic purpura (TTP) is a rare disease which, together with hemolytic uremic syndrome, is subsumed under thrombotic microangiopathy. After stem cell transplantation (SCT), this syndrome represents a possibly fatal complication with a higher incidence in allogeneic SCT than in autologous SCT. Although plasmapheresis offers an encouraging treatment modality in classic TTP, this seems less effective in bone marrow transplant-associated microangiopathy. This is probably due to a different etiology. We present a case of transplant-associated TTP with a fatal outcome despite multiple courses of plasmapheresis.

[Glucagon-secreting malignant neuroendocrine tumor of the pancreas]

BACKGROUND

Glucagonoma is a rare pancreatic tumor of islet alpha 2 cells. Fewer than 200 cases have been reported worldwide, with an estimated incidence of 1 in 20 million. In general, the disease is characterized by a well-defined clinical syndrome which typically shows as necrotic migratory erythema of the skin, weight loss, diabetes mellitus, anemia, cheilosis and stomatitis. Since pancreatic glucagonomas are predominantly located in the tail and findings of radiographic or sonographic examination can remain unspecific, patients often present already metastasis when diagnosis is first established.

CASE REPORT

We report the case of a 67-year-old man with an extended malignant glucagonoma of the pancreas infiltrating already the hilus of the spleen and, additionally, presenting metastatic lesions in the liver and the left adrenal gland. A monohormonal expression of glucagon could be ascertained by serological and immunohistochemical analysis. The special feature of this case is that the tumor was not associated with the characteristic skin rash.

CONCLUSION

An unclear migratory erythema combined with diabetes mellitus and stomatitis/cheilosis should lead to the differential diagnosis of glucagonoma. Isolated glucagonomas are very difficult to find out and often diagnosed already presenting metastasis.

Interferon alpha2b directly induces fibroblast proliferation and transforming growth factor beta secretion of macrophages

To elucidate the effects of interferon alpha2b (IFN-alpha) on normal human bone marrow, fibroblasts from patients without haematopoietic pathology were cultivated and used in stimulation experiments. Further, co-cultures with highly enriched fractions of megakaryocytes and bone marrow macrophages were analysed. In this context, the influence of cell-to-cell interactions and humoral factors was determined in transwell and neutralization studies. Finally, secretion of platelet-derived growth factor (PDGF) and transforming growth factor beta1 (TGF-beta1) by single megakaryocytes and macrophages was examined by using the reverse haemolytic plaque assay (RHPA). Following these experimental designs, a direct proliferative activity of IFN-alpha on bone marrow fibroblasts could be demonstrated. In the unstimulated co-cultures, the megakaryocyte- but not the macrophage-enriched fraction induced fibroblast growth and [3H]-thymidine uptake. This effect was dependent on cell-to-cell contact and also on the influence of TGF-beta and PDGF. In the megakaryocyte-enriched co-cultures, the fibroblast proliferation was not altered by IFN-alpha, but in the macrophage fibroblast cultures addition of IFN-alpha enhanced fibroblast growth and [3H]-thymidine uptake was distinctively higher than in the monocultures. This effect was not obvious in the transwell or neutralization experiments. Finally, IFN-alpha treatment exerted a significantly elevated TGF-beta1 secretion in single macrophages. Our findings are in keeping with the assumption that several pathomechanisms participate in IFN-alpha-induced myelofibrosis, including direct and indirect effects.

Visualization of carbohydrate-binding molecules expressed by myelomono- and erythropoietic cells derived from human bone marrow: an immunoenzymatic double-staining study

Interactions between human haematopoietic and bone marrow stromal cells are governed by complex carbohydrate-mediated adhesion processes. In order to evaluate corresponding carbohydrate-binding sites on human myelo- and erythropoietic cells which were able to react with mono- or oligosaccharides, we established an immunocytochemical double-staining assay. In a first step, cell lineages were visualized using Lewis(x) (CD15) or glycophorin C-specific monoclonal antibodies. The second step included polyacrylamide-conjugated carbohydrate structures. According to our results, the carbohydrate-binding potential of granulopoietic cells increased during the process of maturation, contrasting a reduction of carbohydrate-binding sites on erythroid precursor cells during differentiation. With respect to previous in vitro studies, these findings shed some light on certain aspects of bone marrow homing as well as on the trafficking of mature cellular elements into circulation. It is tempting to speculate that carbohydrate-mediated adhesion mechanisms may be involved in the various functional defects of progenitor cells in chronic myelogenic leukaemia, especially regarding their complex interactions with the marrow microenvironment.

Development of IgG lambda multiple myeloma in a patient with cutaneous CD30+ anaplastic T-cell lymphoma

We report a patient with an epidermotropic cutaneous T-cell lymphoma which transformed into an anaplastic cutaneous CD30+ T-cell lymphoma. Repeated relapses required prolonged systemic PUVA therapy. Two years after diagnosis, the patient had several episodes of infections of the respiratory tract. Serum electrophoresis now revealed significantly reduced polyclonal immunglobulin production and an additional band in the gamma fraction corresponding to IgG lambda monoclonal gammopathy. Thereafter, the patient suffered a pathologic fracture of the dorsolateral 5th rib on the right side and an accumulation of monoclonal plasma cells in the bone marrow confirmed the diagnosis of multiple myeloma (IgG lambda). Accordingly, 6 cycles of cytoreductive chemotherapy (alkeran, decortin) were given. After one year of steady state disease the patient lost weight and bone pain increased while only a few papular eruptions were detectable. Radiography showed multiple small osteolytic areas. A few months later he died with signs of bone marrow insufficiency.

Megakaryocyte induced fibroblast proliferation is enhanced by costimulation with IL-6/IL-3 and dependent on secretory and adhesion events

Experimental data are in keeping with the finding that megakaryocytes isolated from normal human bone marrow may promote fibroblast growth. This effect can be significantly enhanced by interleukin (IL)-3. In this context it has been demonstrated that IL-3 induces the release of platelet-derived growth factor (PDGF) and transforming growth factor beta1 (TGFbeta1) from megakaryocytes, factors known to enhance fibroblast proliferation. The present in vitro study was performed to elucidate the action of several other cytokines which are able to influence the different steps of megakaryocyte maturation and function like stem cell factor (SCF), IL-6, and leukemia inhibitory factor (LIF) as well. Following an appropriate experimental design we were able to show that none of the mentioned cytokines enhanced megakaryocyte dependent fibroblast proliferation in the coculture assays. On the other hand, IL-6 in combination with IL-3 surpassed the IL-3 dependent action significantly. However, the combined IL-3/IL-6 effect was not explainable by an increased PDGF/TGF-beta secretion of the megakaryocytes. In transwell experiments the inhibition of cell-to-cell contact via tissue culture inserts generated a conspicuous impairment of fibroblast growth in the IL-3/IL-6 treated cocultures. This reversal surpassed even the effect on the untreated and IL-3 stimulated cocultures. Hence, a direct contact of both cell types probably inducing adhesion phenomenons and warranting a certain threshold of local PDGF/TGF-beta concentration is a prerequisite for the proliferative effect on fibroblasts in the costimulation experiments. These results are of special interest regarding the evolution of myelofibrosis in chronic myeloproliferative disorders (CMPDs) because (1) various progenitor cells including the megakaryocytic lineage are hypersensitive towards IL-3 and (2) an abnormal secretion of IL-6 is described for megakaryocytes in these disorders.

[Highly differentiated squamous epithelial carcinoma as a late complication of post-traumatic 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.

Polycythemia vera megakaryocytes store and release lysozyme to a higher extent than megakaryocytes in secondary polycythemia (polyglobuly)

Lysozyme, a myelomonocytic marker not only exerts bacteriolytic, but also immunomodulatoric properties and was found to bind to the glycosaminoglycan serglycin, an important constituent of the extracellular matrix (ECM). Pathological serum lysozyme levels were described in chronic myeloproliferative disorders (CMPDs) and other hematological conditions. In this context it is remarkable that in polycythemia rubra vera (PV), characterized by a proliferation particularly of the megakaryo- and erythropoiesis, serum lysozyme levels behave independently of the numbers of myelomonocytic cells in peripheral blood. To elucidate whether megakaryopoiesis might be the source of the increased serum lysozyme, we performed an experimental study on isolated and enriched megakaryocytes derived from bone marrow of patients with PV. Findings were compared to a group of patients with reactive (smoker's) polyglobuly (PG). In confirmation of previous results, quantification of serum lysozyme levels showed a slight elevation in the cohort of PV patients which was not correlated with the leukocyte count. Applying an immunohistochemical assay we were able to demonstrate intracytoplasmic lysozyme storage in megakaryocytes. Moreover, performing the reverse hemolytic plaque assay (RHPA), a technique which enables detection of secreted proteins at the single cell level, we found that 54% of the PV, but only 3% of the PG megakaryocytes spontaneously secreted lysozyme. After rhIL-3 treatment the secretion of lysozyme remained unchanged in PV but increased to 14% in PG. These findings suggest that the extent of megakaryocytic lysozyme secretion might discriminate PV from reactive conditions. Although a direct involvement of lysozyme in the regulation of aberrant megakaryopoiesis in PV is not likely, the results of the present study point to the possibility that lysozyme could be involved in the interactions of PV megakaryocytes with ECM. Moreover, the response to rhIL-3 significantly discriminates PV megakaryocytes from megakaryocytes of the PG group.