An approach for diagnosing plasma cell myeloma by three-color flow cytometry based on kappa/lambda ratios of CD38-gated CD138(+) cells

Flow cytometric immunophenotyping of plasma cells across the spectrum of plasma cell proliferative disorders: A fresh insight with pattern-based recognition

BACKGROUND

The expression pattern of common antigens including cytoplasmic kappa/lambda ratio (cyKLR) was evaluated by flow cytometric immunophenotyping (FCMI) to explore their relevance in discriminating normal and aberrant plasma cells (NPC and APC, respectively) across spectrum of plasma cell proliferative disorders (PCPD).

METHODS

In this prospective analysis, 791 samples from PCPD (treatment naive = 455; partially treated = 336) were evaluated for expression of CD38, CD138, CD45, CD19, CD56, CD27, CD81, CD117, Cy-kappa, and Cy-lambda using FCMI.

RESULTS

Amongst the entire cohort, 20.7% (n = 164) samples displayed only APC, 21% (n = 165) only NPC and 58% (n = 462) showed coexistence of NPC and APC. Using pattern-based recognition (PBR) for three common patterns (CD19 vs. CD56; CD27 vs. CD56 and CD19 vs. CD27), APC was separable from NPC in 93% samples. In 6.5% samples, the gating markers contributed in APC-NPC differentiation and in the remaining 0.5% CD117 and CD81 proved useful. Clonality assessment was found to be crucial to label plasma cell compartment as completely normal or aberrant in 42% cases with either all NPC or all APC. Sixty one out of 462 cases (13%) revealed cyKLR within normal reference range and in these cases; abnormal cyKLR was demonstrable only after gating APC separately based on PBR.

CONCLUSION

Fair discrimination between NPC and APC is achievable in all PCPD samples using eight markers (Gating: CD38, CD138, CD45; PBR:CD19, CD56, CD27; clonality: Cy-kappa and Cy-lambda). Thus, combined assessment of clonality and immunophenotypic aberrancies is required for accurate, reliable and precise assessment of NPC and APC compartments in PCPD.

An approach to small lymph node biopsies: pearls and pitfalls of reporting in the real world

Recent advances in interventional radiology have resulted in the utilization of small lymph node biopsies, including fine-needle aspiration (FNA) and core needle biopsy (CNB) as an initial diagnostic tool in hematopathology. A major challenge to the utilization of FNA and CNB is the limited-to-scant tissue often available. We propose delegation of the task of handling biopsy specimens to the laboratory staff by the biopsy operators, in order to optimize the utilization of the specimen. Furthermore, in order to effectively diagnose hematolymphoid neoplasms a variety of ancillary tests including immunohistochemistry, flow cytometry, molecular analysis, florescence in situ hybridization (FISH) are necessary. We propose morphological evaluation coupled with careful utilization of ancillary studies along with clinical correlation to approach the correct diagnosis. Our morphological assessment considers the types of proliferating cell population: mainly small cells, sheets of large cells, or scattered large cells among small cells. This is followed by employment of the corresponding immunopanel to assess the differential diagnosis in each of the three categories. We also elaborate on the importance for pathologists to become proficient in understanding the limitations of small tissue biopsies as well as the differences in interpretation, and wording their reports to help clinicians and direct them to further investigate and/or to re-biopsy when necessary.

Improving the differential diagnosis between myelodysplastic syndromes and reactive peripheral cytopenias by multiparametric flow cytometry: the role of B-cell precursors

Background

Immunophenotyping is a valuable ancillary technique for the differential diagnosis between myelodysplastic syndromes (MDS) with low bone marrow (BM) blast counts and a normal karyotype, and reactive peripheral (PB) cytopenias. Our aim was to search for the most important variables for this purpose. We also analyzed the age variation of BM B-cell precursors (BCP) and its differences in reactive and clonal cytopenias.

Methods

Immunophenotypic analyzes were performed in BM of 54 patients with MDS (76% with BM blasts <5%) and 35 cases of reactive cytopenias. Healthy allogeneic BM transplantation donors (n = 41) were used as controls. We used a four-color panel of antibodies analyzing 9 granulocytic, 8 monocytic and 6 CD34⁺ cell features.

Results

Asynchronous shift to the left in maturing granulocytes and increase in CD16⁺ monocytes were also found in reactive PB cytopenias, but the most important aberrancies in MDS were seen in myeloid CD34⁺ cells. Decrease in BCP, that is a hallmark of MDS, could also be found in reactive cytopenias, especially in patients >55 years. % BM BCP could be calculated by the formula: (−7.97 × log age) + (4.24 × log % CD34⁺cells) – (0.22 x nr. alterations CD34⁺cells) + 0.577. Corrected R² = 0.467.

Conclusion

Analysis of myelomonocytic precursors and CD34⁺ cells was satisfactory for the differential diagnosis between reactive PB cytopenias and MDS. The most specific alterations were found in CD34⁺ cells. Comparison of the values obtained with those of normal age-matched controls is recommended.

IgG4 overexpression is rare in meningiomas with a prominent inflammatory component: a review of 16 cases

Meningiomas with prominent inflammation are traditionally classified as "lymphoplasmacyte-rich meningioma" (LPM). Both inflammatory and neoplastic meningeal proliferations have recently been linked to IgG4 disease, although a potential association with LPM has not been previously explored. Sixteen meningiomas with inflammatory cells outnumbering tumor cells were further characterized by CD3, CD20, CD68 and/or CD163, CD138, kappa, lambda, IgG and IgG4 immunostains. There were 11 female and 4 male patients, ranging from 22 to 78 (median 59) years of age. Tumors consisted of 10 World Health Organization (WHO) grade I, 5 grade II and 1 grade III LPMs. Immunohistochemically, the most numerous cell type was the macrophage in all cases followed by CD3-positive T cells and fewer CD20-positive B cells. Plasma cells ranged from moderate-marked (N = 5) to rare (N = 7), or absent (N = 4). Maximal numbers of IgG4 plasma cells per high power field (HPF) ranged from 0 to 32, with only two cases having counts exceeding 10/HPF. The IgG4/IgG ratio was increased focally in only two cases (30% and 31%). Additionally, plasma cells represented only a minor component in most examples, whereas macrophages predominated, suggesting that "inflammation-rich meningioma" may be a more accurate term. The inflammatory stimulus for most cases remains to be elucidated.

Cell surface-associated anti-MUC1-derived signal peptide antibodies: implications for cancer diagnostics and therapy

The MUC1 tumor associated antigen is highly expressed on a range of tumors. Its broad distribution on primary tumors and metastases renders it an attractive target for immunotherapy. After synthesis MUC1 is cleaved, yielding a large soluble extracellular alpha subunit containing the tandem repeats array (TRA) domain specifically bound, via non-covalent interaction, to a smaller beta subunit containing the transmembrane and cytoplasmic domains. Thus far, inconclusive efficacy has been reported for anti-MUC1 antibodies directed against the soluble alpha subunit. Targeting the cell bound beta subunit, may bypass limitations posed by circulating TRA domains. MUC1's signal peptide (SP) domain promiscuously binds multiple MHC class II and Class I alleles, which upon vaccination, generated robust T-cell immunity against MUC1-positive tumors. This is a first demonstration of non-MHC associated, MUC1 specific, cell surfaces presence for MUC1 SP domain. Polyclonal and monoclonal antibodies generated against MUC1 SP domain specifically bind a large variety of MUC1-positive human solid and haematological tumor cell lines; MUC1-positive bone marrow derived plasma cells obtained from multiple myeloma (MM)-patients, but not MUC1 negative tumors cells, and normal naive primary blood and epithelial cells. Membranal MUC1 SP appears mainly as an independent entity but also co-localized with the full MUC1 molecule. MUC1-SP specific binding in BM-derived plasma cells can assist in selecting patients to be treated with anti-MUC1 SP therapeutic vaccine, ImMucin. A therapeutic potential of the anti-MUC1 SP antibodies was suggested by their ability to support of complement-mediated lysis of MUC1-positive tumor cells but not MUC1 negative tumor cells and normal naive primary epithelial cells. These findings suggest a novel cell surface presence of MUC1 SP domain, a potential therapeutic benefit for anti-MUC1 SP antibodies in MUC1-positive tumors and a selection tool for MM patients to be treated with the anti-MUC1 SP vaccine, ImMucin.