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Background: Indistinct and analogous histopathological features of various fibro-osseous lesions make establishing a definitive diagnosis a challenge. There is a need for additional molecular and histochemical tools to support and differentiate these lesions in order to establish a concrete diagnosis., Materials and Methods: A retrospective analysis of biopsied lesions in formalin-fixed paraffin-embedded sections (10 cases each of fibrous dysplasia, ossifying fibroma, and cement-osseous dysplasia) retrieved from the archives was studied for immunoexpression of osteocalcin (quantitative analysis in osteocytes), collagen characterization using Azan, Picrosirus, and Toluidine blue stain for evaluating intensity and localization of collagen fibers, and morphometric analysis of vasculature (for evaluating mean vessel density as square microns)., Results: Positive immunostaining of osteocalcin suggested mutations of the GNAS-1 gene found in fibrous dysplasia indirectly, as it is a negative regulator of bone formation. Osteocalcin immunopositivity was quantitatively measured in the fibro-osseous lesions, with fibrous dysplasia measuring 14.47 ± 3.628 as compared to ossifying fibroma measuring 5.23 ± 1.33, followed by cemento-osseous dysplasia measuring 2.30 ± 1.409. Toluidine blue suggests the presence of oxytalan fibers (resistant to acid hydrolysis) in ossifying fibroma and cemento-osseous dysplasia, pointing toward the pathogenesis of the lesion. Azan stain and Picrosirus (under a polarizing microscope) helped in distinguishing hard tissue characteristics (70% of cases of fibrous dysplasia showed only a magenta component followed by intermixed magenta with a blue component in 20% of cases and only 10% of cases showed magenta with blue borders whereas for ossifying fibroma, 40% of cases depicted magenta with blue borders along with the other 40% with intermixed magenta with blue component). The mean vessel density was also highest in fibrous dysplasia measuring 7.90 ± 1.079 (in Sq. micron area), followed by ossifying fibroma and cemento-osseous dysplasia., Conclusion: The diagnosis of fibro-osseous lesions by hematoxylin and eosin alone is confusing and thus should be supported by relatively simple histomorphometric analysis for better treatment outcomes. At the diagnostic stage of fibro-osseous lesions, evaluation of intralesional vessel size, reliable molecular marker, and histochemical nature can aid in differentiating fibrous dysplasia from central ossifying fibroma and cemento-osseous dysplasia alongside, other clinical, radiographic and pathological criteria. These parameters help in the diagnostic decision-making of fibro-osseous lesions., (Copyright © 2024 Copyright: © 2024 Indian Journal of Pathology and Microbiology.)

Aims: MYC rearrangements with or without BCL2 rearrangements have been shown to be associated with poor prognosis and inferior survival in diffuse large B-cell lymphomas (DLBCL). Most of these cases are still diagnosed by fluorescent in situ hybridisation (FISH) testing, which is expensive, requires expertise and is not routinely available in all laboratories. Immunohistochemistry (IHC) is widely available and has the potential to be used as a screening test to identify cases with increased protein expression and select cases that require confirmatory testing. We correlated the expression of MYC and BCL2 by IHC with FISH studies in an attempt to define a cut-off value, which can be used by laboratories to select cases requiring confirmatory FISH testing. The prevalence of MYC-positive DLBCL and double-hit lymphoma (DHL) has also been studied., Methods: 209 cases comprising of 15 cases of Burkitt lymphoma (BL), 13 cases of intermediate BL/DLBCL and 181 cases of DLBCL were included. IHC and FISH for MYC and BCL2 were performed and the results were correlated., Results: The prevalence of MYC-positive DLBCL and MYC/BCL2DHL was 13.4% and 7.4%, respectively, in our study. Germinal-centre subtype was more common in MYC-positive DLBCL and DHL. MYC-positive DLBCL also showed higher median Ki-67 (>90%) and CD10 positivity as compared with MYC-negative cases., Conclusions: IHC can be used for screening cases, which require further confirmatory FISH testing. We recommend a cut-off value of ≥30% for MYC by IHC; however, international standardisation of these values is necessary to provide uniformity among laboratories., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Myeloperoxidase (MPO) is an unequivocal marker of myeloid differentiation which is routinely detected using cytochemistry (CC), flow cytometry (FC) and immunohistochemistry (IH). Several studies have compared the use of two of these methods, but to our knowledge none has compared all three techniques. We compared the performance of these three modalities in the detection of MPO in 158 cases of acute myeloid leukaemia (AML). Discrepancies were noted in a total of 28 cases. Of 110 cases in which all three modalities were performed, 23 cases showed discrepancies. CC was the least sensitive marker, being negative in 11 of 23 cases in the presence of positive IH and/or FC. IH was the most sensitive marker with only one case being negative in the presence of a positive result by FC and/or CC. The results highlight the necessity of employing more than one method in determining the presence of MPO and confirm the important role of IH in the diagnosis of AML particularly in cases where MPO is not detected by CC and FC.

Background: The B cell lymphoma-2 gene is a proto-oncogene whose protein product inhibits apoptosis. Its role is associated with keeping cells alive, but not by stimulating them to proliferation, as other proto-oncogenes do. Increased expression of protein product of Bcl-2 gene appears in the early phase of carcinogenesis leading to apoptosis impairment and in consequence to the progression of neoplastic changes.Objective: To evaluate and compare the expression of Bcl-2 protein in oral epithelial dysplasia and oral squamous cell carcinoma (OSCC).Materials and Methods: Sixty cases of formalin-fixed paraffin-embedded archival specimens comprising of 30 cases of leukoplakia with oral epithelial dysplasia and 30 cases of OSCC were taken for immunohistochemical analysis using monoclonal antibody against anti-human Bcl-2 oncoprotein.Results: Immunostaining for Bcl-2 protein was identified in basal and parabasal layers as granular cytoplasmic staining in oral epithelial dysplasia. In OSCC, Bcl-2 immunoreactivity was most prominent in the peripheral cells of the infiltrating tumor islands which diminished toward the center in well-differentiated and moderately differentiated OSCC, whereas stronger and more diffuse expression of Bcl-2 oncoprotein was seen in poorly differentiated OSCC. Overall positivity of 26.7% (8/30) was observed in oral epithelial dysplasia and 30% (9/30) in OSCC in this study.Interpretation and Conclusion: Altered expression of Bcl-2 oncoprotein may be an early molecular event which leads to prolonged cell survival, increased chances of accumulation of genetic alterations, and subsequent increase in malignant transformation potential. [ABSTRACT FROM AUTHOR]

Outlines the role of bone marrow immunohistology in the laboratory evaluation of patients with suspected and established plasma cell neoplasms. Identification of antibodies which are useful for plasma cell immunohistology; Assessment of minimal residual disease; Importance of immunohistology in monitoring low amounts of disease after high dose treatment.

Provides information on the paraffin section immunotyping (PSI) of leukemia. Importance of technical considerations in PSI; Comparison between PSI and flow cytometry; Discussion on acute leukemia; Role of immunohistology in marrow trephine; Antibodies that may be helpful in subtyping acute myeloid leukemia.