Differentiation of plasma cell infiltrates in the bone marrow. A clinicopathological study on 80 patients including immunohistochemistry and morphometry

Histology and immunohistology of bone marrow biopsy in multiple myeloma

B5-fixed/paraffin-embedded Jamshidi needle biopsies from 125 multiple myeloma patients were reviewed according to both morphological and immunohistological criteria. At microscopic examination, the following parameters were evaluated: i) grade of malignancy (low = 56; intermediate = 50; high = 19); ii) growth pattern (interstitial +/- sheets/nodules = 90; nodular = 13; packed marrow = 18; sarcomatous = 4); III) histological stage (I = 64; II = 35; III = 26). Comparison of the findings in trephine biopsies and aspirates showed that in 30% of the cases the latter led to an underestimation of the tumor burden. Immunohistochemical determination of Ig easily allowed: i) differential diagnosis from exuberant reactive plasmacytosis; ii) recognition and counting of neoplastic plasma cells; iii) detection of minimal residual disease after treatment. Immunohistochemistry also confirmed phenotypic aberration of neoplastic plasma cells, showing positivity for CD45, EMA, and cytokeratins in 14%, 59%, and 25% of the cases, respectively. Furthermore, it displayed expression of the P-glycoprotein in 4/8 resistant cases. These findings underline that routinely processed Jamshidi needle biopsies can be of great value in the study of patients with multiple myeloma.

Clinical Relevance of Bone Marrow Fibrosis and CD34-Positive Cell Clusters in Primary Myelodysplastic Syndromes

Purpose

We studied bone marrow (BM) histologic abnormalities in myelodysplastic syndromes (MDS) classified according to WHO criteria to determine their clinical correlates and prognostic value.

Patients and Methods

Three hundred one consecutive patients were retrospectively evaluated for BM fibrosis and CD34 immunoreactivity. Marrow fibrosis was assessed following the European consensus guidelines.

Results

Moderate to severe BM fibrosis was detected in 17% of cases and was associated with multilineage dysplasia (P = .001), high transfusion requirement (P < .001), and poor-risk cytogenetics (P = .007). CD34+ cell clusters were found in 23% of patients and were associated with WHO categories with excess of blasts (P < .001) and poor-risk cytogenetics (P = .001). In multivariable analysis, BM fibrosis and presence of CD34+ cell clusters had independent negative impact on overall survival (P < .001 and P = .019, respectively) and leukemia-free survival (P < .001 and P = .004, respectively). A hierarchical clustering analysis identified three subsets of patients with distinct clinical features. One cluster consisted mainly of patients with BM fibrosis, multilineage dysplasia, and high transfusion requirement; these individuals had lower overall survival and leukemia-free survival (P = .001 and P < .001, respectively). Within patients stratified according to International Prognostic Scoring System and WHO classification–based Prognostic Scoring System categories, BM fibrosis involved a shift to a one-step more advanced risk group.

Conclusion

BM fibrosis identifies a distinct subgroup of MDS with multilineage dysplasia, high transfusion requirement, and poor prognosis and represents an independent prognostic factor that may be useful in clinical decision making. Furthermore, the presence of CD34+ cell clusters is an independent risk factor for progression to acute leukemia.

Assessment of bone marrow plasma cell infiltrates in multiple myeloma: the added value of CD138 immunohistochemistry

Assessment of bone marrow involvement by malignant plasma cells is an important element in the diagnosis and follow-up of patients with multiple myeloma and other plasma cell dyscrasias. Microscope-based differential counts of bone marrow aspirates are used as the primary method to evaluate bone marrow plasma cell percentages. However, multiple myeloma is often a focal process, a fact that impacts the accuracy and reliability of the results of bone marrow plasma cell percentages obtained by differential counts of bone marrow aspirate smears. Moreover, the interobserver and intraobserver reproducibility of counting bone marrow plasma cells microscopically has not been adequately tested. CD138 allows excellent assessment of plasma cell numbers and distribution in bone marrow biopsies. We compared estimates of plasma cell percentages in bone marrow aspirates and in hematoxylin-eosin- and CD138-stained bone marrow biopsy sections (CD138 sections) in 79 bone marrows from patients with multiple myeloma. There was a notable discrepancy in bone marrow plasma cell percentages using the different methods of observation. In particular, there was a relatively poor concordance of plasma cell percentage estimation between aspirate smears and CD138 sections. Estimates of plasma cell percentage using CD138 sections demonstrated the highest interobserver concordance. This observation was supported by computer-assisted image analysis. In addition, CD138 expression highlighted patterns of plasma cell infiltration indicative of neoplasia even in the absence of plasmacytosis. We conclude that examination of CD138 sections should be considered for routine use in the estimation of plasma cell load in the bone marrow.

Bone marrow aplasia with prominent atypical plasmacytic proliferation preceding acute lymphoblastic leukemia

A two-year-old boy presented with pancytopenia. Bone marrow examination revealed an aplastic marrow with prominent immature plasma cell proliferation, which mimicked plasma cell leukemia. Immunohistochemistry, however, revealed a polyclonal population consistent with a reactive process, excluding plasma cell neoplasia. Administration of granulocyte-colony stimulating factor resulted in recovery of normal hematopoiesis with resolution of plasmacytosis. Seven months later, the patient had an elevated white blood cell count and bone marrow findings diagnostic of acute lymphoblastic leukemia. To the best of our knowledge this is the first reported case of bone marrow aplasia with prominent polyclonal plasmacytosis presenting as a prodrome of acute lymphoblastic leukemia in childhood.

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.

CD34 immunohistochemistry of bone marrow biopsies: prognostic significance in primary myelodysplastic syndromes

Bone marrow (BM) biopsies from 58 patients with primary myelodysplastic syndrome (MDS) were studied using QBEND10, a monoclonal antibody that recognizes the human progenitor CD34 antigen in routine aldehyde-fixed paraffin-embedded samples. FAB subtypes were RA (5 patients), RARS (9 patients), RAEB (20 patients), RAEBt (11 patients), CMML (3 patients). In addition, 10 MDS patients whose BM biopsies revealed heavy reticulum fibrosis were included. Neither the percentage of CD34+ cells nor the number of CD34+ aggregates (defined as clusters of 3 or more cells) correlated with the presence and morphology of abnormal localizations of immature precursors (ALIP). When all patients were considered, median survival was 69 months in those with less, and 25 months in patients with more than 1% CD34+ cells (P < 0.05). Median survival was 15 months in patients with CD34+ aggregates and 41 months in those without aggregates (P = 0.0017). When RAEB patients were considered median survival was 41 months in those with less than 1%, and 29 months in those with more than 1% CD34+ cells; the 4-year survival chance was 45% in the former and 18.3% in the latter group. Therefore, CD34 positivity of more than 1% identifies a subset of RAEB patients with shorter life expectancy. In addition, leukemic transformation was observed in 11 of 35 patients (31%) with no CD34 aggregates, but in 14 of 23 patients (60%) with aggregates (P < 0.05). CD34 immunostaining, which can be easily performed on routinely prepared BM biopsies, was found to be a powerful prognostic tool for predicting survival and outcome in MDS.

Diagnostic criteria and histologic grading in multiple myeloma: histologic and immunohistologic analysis of 176 cases with clinical correlation

Diagnostic criteria in myeloma have not been completely standardized or tested for accuracy; furthermore, marrow findings of prognostic value have not been clearly identified. We studied 176 patients with myeloma to determine the relative value of marrow differential, tissue sections, and immunohistology singly or in concert in the diagnosis of myeloma and to correlate morphologic features with prognosis. Controls were patients with benign marrow plasmacytosis. Homogeneous nodules of plasma cells at least 1/2 high-power field and/or monotypic aggregates of plasma cells filling at least one interfatty marrow space correctly identified myeloma in 83.5% of cases, with no false positives. The current numerical criteria of marrow plasmacytosis > or = 10% occurred in 17.1% of the controls, and 39.7% of patients with myeloma had less than 10% marrow plasmacytosis at presentation. Myeloma was graded histologically into categories of none/minimal, moderate, and marked dysplasia on the basis of dysplastic features and mitoses; these categories correlated well with clinical outcome, with median length of survival of 32.9, 25.2, and 12.9 months, respectively (overall median length of survival of 123 patients with myeloma, 29.2 months). Packing of marrow by tumor and mitoses measuring at least 5/high-power field regardless of grade also was associated with a poor prognosis (median lengths of survival, 15.2 and 11 months, respectively). Myeloma may be diagnosed in the great majority of cases by demonstrating homogeneous nodules and/or monotypic aggregates of plasma cells in the marrow. Prognostic features were shown to include marked dysplasia, mitoses, packing of marrow by tumor, and clinical stage.

Bone marrow trephine biopsy in lymphoproliferative disease

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Comparison of plasma cell infiltration in bone marrow biopsies and aspirates in patients with multiple myeloma

In 54 patients with multiple myeloma plasma cell infiltration was compared in bone marrow biopsies and aspirates. In 48% of cases plasma cell infiltration was comparable, in 48% infiltration in the aspirate was lower than in the biopsy. In only two cases more plasma cells were found in the aspirate. Eleven patients (20%) had less than 20% plasma cells in the aspirate and more than 50% in the biopsy. Underestimation of plasma cell load especially seems to occur in patients with a focal growth pattern of multiple myeloma or when strong fibrosis is present. 69% of patients with stage III, according to Durie & Salmon (1975), and 76% of patients with a high beta 2-microglobulin had more than 50% plasma cells in the biopsy, indicating that these parameters, which are based on tumour load, are influenced by other factors as well. The bone marrow biopsy is of superior value for direct estimation of the tumour load in multiple myeloma compared to bone marrow aspirates. A prospective study is needed to determine its prognostic significance.

Immunoglobulin gene rearrangement in multiple myeloma: limitations of Southern blot analysis

Thirty-six patients with early and advanced multiple myeloma were investigated with Southern blot analysis to determine the presence of immunoglobulin gene rearrangement as evidence of clonality. Rearrangements were not uniformly found, being detected in only 14 of 19 patients with newly diagnosed myeloma and in 15 of 17 cases of clinically advanced myeloma. A correlation between percentage of bone marrow plasma cells and detection of immunoglobulin gene rearrangement was noted; however, in four cases of early myeloma with > 10% marrow plasma cells, no rearrangement was found. These results suggest that Southern blot analysis may not be an optimal method for the determination of clonality in plasma cell dyscrasias or, alternatively, that a proportion of the plasma cells found on bone marrow examination in some patients with early myeloma may not be monoclonal.

Bone marrow diagnosis in lymphoproliferative disorders: comparison of results obtained from conventional histomorphology and immunohistology

In this study we have investigated 313 bone marrow biopsies from 280 patients with lymphoproliferative disorders. Trephines were sectioned transversely to obtain one cylinder for cryostat sectioning and immunostaining and a second for histomorphological evaluation using a plastic-embedding technique. The results obtained by histomorphological and immunohistological evaluation were compared for their contribution to staging and classification. Using both techniques, bone marrow involvement was seen in 3/43 (7.0%) biopsies from patients with Hodgkin's disease and in 193/270 (71.5%) cases with non-Hodgkin's lymphoma, including multiple myeloma and acute lymphocytic leukaemia. Immunohistology proved superior in detecting minimal mainly interstitial bone marrow infiltration in 15 leukaemia/lymphoma cases. Biopsies showing infiltration with both methods (n = 157) were re-examined for classification of lymphomatous infiltrates. Whereas immunohistology did not provide additional information in cases with Hodgkin's disease and myeloma, this method was crucial for establishing the definitive diagnosis in a number of cases with acute lymphocytic leukaemia and non-Hodgkin's lymphoma. In all of six leukaemia cases, in which no or inadequate material was available for immunophenotyping of cell suspensions, immunohistology clearly defined the subtype. In the 140 cases of non-Hodgkin's lymphoma the majority of cases (76.4%) were identically classified. In some cases, with important prognostic and therapeutic implications, immunohistology alone provided the definitive diagnosis: T-cell lymphoma (n = 2), hairy cell leukaemia (n = 2) and centrocytic non-Hodgkin's lymphoma (n = 3). Bone marrow immunohistology is, therefore, an important supplement for classical lymphoma/leukaemia diagnosis. The differences observed between histomorphology and immunohistology emphasize the importance of lymph node biopsy in lymphoma classification.

Myelodysplastic syndrome with increased marrow fibrosis: a distinct clinico-pathological entity

Seventeen cases of myelodysplastic syndrome (10 primary and seven secondary to previous radio-chemotherapy), characterized by trilineage dysplasia, severe bone marrow fibrosis and a high number of megakaryocytes, are described. All of these patients had similar clinical and prognostic features consisting of pancytopenia, modest or absent visceral enlargement and poor survival. The use of CD61 antibodies, which recognize megakaryocytic cells at all stages of maturation, confirmed that these patients had a higher number of these cells than either normal subjects or patients affected by myelodysplastic syndrome (MDS) without fibrosis. Furthermore, primary and secondary MDS with fibrosis, although clinically and histopathologically similar, differed in terms of the number of megakaryoblasts which were significantly higher in primary forms (P less than 0.02). We conclude that MDS with fibrosis may represent a clinicopathological entity which needs to be distinguished from other MDS subtypes as well as from idiopathic myelofibrosis or malignant myelosclerosis.

Osteoclasts and bone remodeling in chronic myeloproliferative disorders. A histochemical and morphometric study on trephine biopsies in 165 patients

In 165 patients with chronic myeloproliferative disorders (CMPD) a morphometric and histochemical study was performed on trephine biopsies of the bone marrow to elucidate osseous remodeling by assessment of trabecular bone area (planimetry) and number of osteoclasts. Osteoclastic elements were identified by the tartrate-resistant acid phosphatase method. In addition to control specimens (n = 20) subtypes of CMPD included chronic myeloid leukemia (CML, n = 65), primary (essential) thrombocythemia (PTH, n = 25), polycythemia vera rubra (P. vera, n = 25) and agnogenic myeloid metaplasia (AMM, n = 50). AMM was discriminated into a so-called early hyperplastic stage without gross myelofibrosis (n = 19) and an overt or advanced stage showing fibro-osteosclerotic changes (n = 31). Total area of trabecular bone and counts for osteoclasts (uni- and multi-nucleated cells as well as a-nuclear cytoplasmic fragments) were not significantly increased in CML, PTH, P. vera and in the initial hypercellular stages of AMM. In contrast to these results, in advanced stages of AMM there was a significant increase in total bone area associated with a high count for all osteoclastic elements and apparently also an increased number of osteoblasts. It is speculated that the marked increase in osteoclastic-osteoblastic elements in late stages of AMM possibly reflects an imbalance of calcitriol (1.25-dihydroxyvitamin D 3) on skeletal homeostasis. This abnormal osseous remodeling may be mediated by the atypical megakaryocytic proliferation in this disorder, which is always a conspicuous feature of bone marrow biopsies.