Specific Polo-Like Kinase 1 Expression in Nodular Lymphocyte-Predominant Hodgkin Lymphoma Suggests an Intact Immune Surveillance Program.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) is a rare and relatively indolent B-cell lymphoma. Characteristically, the [lymphocyte-predominant (LP)] tumor cells are embedded in a microenvironment enriched in lymphocytes. More aggressive variants of mature B-cell and peripheral T-cell lymphomas exhibit nuclear expression of the polo-like kinase 1 (PLK1) protein, stabilizing MYC (alias c-myc) and associated with worse clinical outcomes. This study demonstrated expression of PLK1 in the LP cells in 100% of NLPHL cases (n = 76). In contrast, <5% of classic Hodgkin lymphoma cases (n = 70) showed PLK1 expression within the tumor cells. Loss-of-function approaches demonstrated that the expression of PLK1 promoted cell proliferation and increased MYC stability in NLPHL cell lines. Correlation with clinical parameters revealed that the increased expression of PLK1 was associated with advanced-stage disease in patients with NLPHL. A multiplex immunofluorescence panel coupled with artificial intelligence algorithms was used to correlate the composition of the tumor microenvironment with the proliferative stage of LP cells. The results showed that LP cells with PLK1 (high) expression were associated with increased numbers of cytotoxic and T-regulatory T cells. Overall, the findings demonstrate that PLK1 signaling increases NLPHL proliferation and constitutes a potential vulnerability that can be targeted with PLK1 inhibitors. An active immune surveillance program in NLPHL may be a critical mechanism limiting PLK1-dependent tumor growth.

Detection and Quantification of the Epstein-Barr Virus in Lymphoma Patients from Ethiopia: Molecular and Serological Approaches.

The Epstein-Barr virus (EBV) is a known oncogenic virus associated with various lymphoma subtypes throughout the world. However, there is a lack of information regarding EBV prevalence in lymphoma patients, specifically in Ethiopia. This study aimed to investigate the presence of the EBV and determine its viral load in lymphoma patients from Ethiopia using molecular and serological approaches. Lymphoma patient samples were collected from the Ethiopian population. DNA and serum samples were extracted and subjected to molecular detection methods, including quantitative polymerase chain reaction (qPCR) analysis targeting the EBNA1 gene. Serological analyses were performed using an enzyme-linked immunosorbent assay (ELISA) to detect EBV viral capsid antigen IgG antibodies. EBV DNA was detected in 99% of lymphoma patients using qPCR, and serological analyses showed EBV presence in 96% of cases. A high EBV viral load (>10,000 EBV copies/mL) was observed in 56.3% of patients. The presence of high EBV viral loads was observed in 59.3% of HL patients and 54.8% of NHL patients. This study provides important insights into the prevalence and viral load of the EBV among lymphoma patients in Ethiopia. The findings contribute to the limited knowledge in this area and can serve as a foundation for future research.

Transformed Plasmablastic Lymphoma Presenting With Marked Lymphocytosis and Spontaneous Tumor Lysis Syndrome.

The clinicopathology entity of plasmablastic lymphoma (PBL), despite broad recognition by the World Health Organization (WHO), represents a diagnostic challenge due to its overlapping features and scarce occurrence. Often, PBL arises in immunodeficient, elderly male patients, most notably those who are human immunodeficiency virus (HIV)-positive. More infrequent, cases of transformed PBL (tPBL) evolved from another hematologic disease have been identified. Herein, we describe a case of a 65-year-old male transferred from a neighboring hospital with pronounced lymphocytosis and spontaneous tumor lysis syndrome (sTLS) presumed to be chronic lymphocytic leukemia (CLL). Utilizing a complete clinical, morphologic, immunophenotypic, and molecular evaluation, we arrived at a final diagnosis of tPBL with sTLS, suspected to have evolved from the NF-κB/NOTCH/KLF2 (NNK) genetic cluster of splenic marginal zone lymphoma (SMZL) (NNK-SMZL), a potential transformation and presentation, to our knowledge, not previously reported. However, definitive clonality testing was not performed. In this report, we also outline the diagnostic and educational considerations we faced in discerning tPBL from other more common B-cell malignancies which can present similarly, such as CLL, mantle cell lymphoma, or plasmablastic myeloma. We summarize recently reported molecular, prognostic, and therapeutic considerations for the treatment and recognition of PBL, including the successful implementation, in our patient, of bortezomib to an EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin) regimen with prophylactic intrathecal methotrexate, who has since achieved complete remission (CR) and entered clinical surveillance. Lastly, this report briefly highlights the challenge we faced in this area of hematologic typification that necessitates additional review and discussion by the WHO: tPBL with potential double-hit cytogenetic versus double-hit lymphoma with a plasmablastic phenotype.

A Case Report: Kikuchi Disease Associated With a Positive Auto-Immune Panel Triggered by COVID-19 Infection.

Kikuchi disease (KD) is a rare, benign inflammatory condition characterized by fever and cervical lymphadenopathy. While the pathogenesis is largely unknown, Kikuchi disease onset has strong associations with various infections and autoimmune conditions. There are few reported cases of Kikuchi disease triggered by coronavirus disease 2019 (COVID-19) infection or vaccination. A 43-year-old Filipina female with a history of anemia and recent uncomplicated COVID-19 infection one month prior presented with a one-month history of progressive weakness, fatigue, anorexia with 30-pound weight loss, fevers, odynophagia, and new-onset hematemesis. Initial laboratory findings were most significant for a markedly elevated ferritin level prompting initial concern for hemophagocytic lymphohistiocytosis. Admission imaging revealed diffuse cervical and thoracic lymphadenopathy. Lymph node biopsy revealed paracortical expansion with numerous histiocytes with phagocytosed necrotic debris and germinal center necrosis, consistent with Kikuchi disease. She received supportive care without any medical intervention and improved clinically with the resolution of lymphadenopathy and inflammatory laboratory markers. This report describes the initial presentation and subsequent diagnostic workup of a unique and infrequently documented case of Kikuchi disease secondary to COVID-19 infection. This case highlights general constitutional symptoms, including fever and lymphadenopathy as defining characteristics of Kikuchi disease. During diagnostic workup, it is important to rule out hematologic emergencies, such as hemophagocytic lymphohistiocytosis, which can present similarly. This case also reports a concurrent autoimmune workup, which was positive at the time of the Kikuchi disease diagnosis. COVID-19 infections and deaths, while declining in the post-pandemic period, remain significant, thus diagnostic consideration for conditions of self-limited disorders, such as Kikuchi disease, should be considered.

A digital method to interpret the C-MYC stain in diffuse large B cell lymphoma.

Diffuse large B-cell lymphoma, not otherwise specified (DLBCL, NOS) is a heterogenous group of aggressive lymphomas. C-MYC expression by immunohistochemical stain (IHC) is shown to be an independent prognostic factor in DLBCL. In the clinical setting, MYC stain is currently evaluated by manual quantification with a minimum positivity cut-off 40%. Manual quantification methods can be subjective and may show intra- and interobserver variability and variability between centers. Thus, stains which require definitive quantification such as MYC needs better standardized and precise methods. Here we present a simple digital algorithm for quantitative evaluation of MYC stain in DLBCL, NOS. For this, slides immunostained for C-MYC were scanned at 40X with a high-resolution, Philips Ultra Fast scanner (Koninklijke Philips N.V. Cambridge, MA). The images were manually assessed and appropriate areas with neoplastic cells were selected. For quantification, positive and negative C-MYC staining nuclei were scored using a modified Visiopharm APP Nuclei Detection, AI (Brightfield) using Visiopharm Image Analysis software (Visiopharm, Hørsholm, Denmark version 2018.09). The percentage positivity resulted by the digital method was concordant with the pathologist's interpretation with statistical significance (rs: 0.85968; p (2-tailed) = 0). Minor disadvantages were observed including failure to detect very weak staining and inability to separate neoplastic and non-neoplastic nuclei when admixed in the same area. If combined with a quick manual evaluation, a digital method like this with precision and reproducibility will be of great use in quantitative evaluation of MYC and other similar stains in clinical setting and will reduce intra- and interobserver variability.

Intensity of antigen expression reflects IGHV mutational status and Dohner-defined prognostic categories in chronic lymphocytic leukemia, monoclonal B-cell lymphocytosis, and small lymphocytic lymphoma.

We demonstrate the prognostic utility of antigen quantitation in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and monoclonal B-cell lymphocytosis (MBL). Median antibody-bound-per-cell (ABC) of CD20, CD22, CD25, CD19, and %CD38(+) was determined in CLL (185/208), SLL (8/208) and MBL (15/208) cases by flow cytometry, then compared to Dohner-classification, immunoglobulin status (mutated, IGHV-M; unmutated, IGHV-U), CLL-IPI risk and time to first treatment (TTFT). Trisomy 12 cases showed increased %CD38-expression (p = .0379). Higher %CD38 was observed in IGHV-U versus IGHV-M (p = .0003). CD20ABC was increased in IGHV-U versus IGHV-M (p = .006). Del13q cases demonstrated lower CD22ABC (p = .0198). Cases without cytogenetic abnormality exhibited higher CD19ABC (p = .0295) and CD22ABC (p = .0078). Del17p cases demonstrated lower CD25ABC (p = .0097). High and very-high CLL-IPI risk groups were associated with high CD38-expression (p = .02) and low CD25ABC (p = .0004). Shortened TTFT was associated with high CD38-expression (p < .0001). Interestingly, high CD25ABC trended toward shortened TTFT (p = .07). Quantitative antigen expression reflects CLL-IPI risk groups and Dohner-classification.

Unusual cerebrospinal fluid finding of intracytoplasmic granules in metaplastic carcinoma of the breast with acinar differentiation.

Cerebrospinal fluid (CSF) evaluation for total and differential cell count is a common practice in pathology for evaluation of various disease conditions. Although rare, these CSF samples yield interesting and unusual morphological findings, which are not only of academic interest, but also may play key roles in diagnosis. For diagnosing metastatic carcinoma in brain and meninges, CSF examination is one of the important tools along with imaging studies. Metaplastic breast carcinoma (MBC) encompasses a rare (<1% of all breast cancers), aggressive and highly heterogeneous group of tumors. MBC is almost always estrogen receptor, progesterone receptor and Her2 negative (triple negative) and shows frequent early distant metastases as well as sub-optimal response to systemic therapies. The involvement of leptomeninges is most commonly associated with these triple- negative subtypes. In this report, we present an unusual case of malignant cells with prominent intracytoplasmic granules in CSF smears of a 46-year-old female with metastatic MBC with acinar differentiation. An extensive review of literature in English language did not return any other reports of a similar finding.

The life and death of the germinal center.

The formation, development and dissolution of germinal centers is a major part of immune system function. It is important to differentiate neoplastic processes from follicular hyperplasia and regressive follicular changes. Better understanding of germinal center development and dissolution also provides diagnostic clues to the underlying pathologic process. It is also important in identifying the immune basis of different pathologic entities as well as in immunotherapy decision making and follow up. In this study, we characterize the immunoarchitecture of lymphoid follicles with a focus on germinal center in one representative case, each of commonly encountered benign and malignant lymph node disorders, with morphologic and immunohistochemical alterations of germinal centers. The cases include reactive follicular hyperplasia (FH), florid follicular hyperplasia (FFH), follicular lymphoma (FL), angioimmunoblastic T-cell lymphoma (AITL), hyaline-vascular Castleman disease (HVCD), progressive transformation of germinal centers, nodular lymphocyte predominant Hodgkin lymphoma (NLPHL), lymphocyte-rich classic Hodgkin lymphoma (LR-CHL), human immunodeficiency virus (HIV)-associated follicular dissolution and chronic lymphocytic leukemia (CLL) with proliferation centers (PC). A panel of antibodies were used namely CD3, CD20, CD10, BCL2, BCL6, CD21, CD23, CD35, FOXP1, GCET1, HGAL/GCET2, LMO2, MUM1, IgD, Ki67, PD1 and PD-L1. We found that these entities show distinct immunoarchitectural patterns of germinal center formation, development and regression, particularly, the distribution of mantle zone B-cells, follicular helper T cells (Tfh) and FDC meshworks, confirming the influence of antigenic stimulation and status of immune system in these changes. This also confirms the interrelationship of underlying immunologic mechanisms in these disease processes.

Diagnosis of Hodgkin lymphoma in the modern era.

The Hodgkin lymphomas are a family of unique lymphoma subtypes, in which the nature of the neoplastic cell was enigmatic for many years. Much of the mystery has been solved, with all forms now considered to be of B-cell origin, in most cases of germinal centre derivation. Today we recognize Hodgkin lymphoma as an eponym that encompasses multiple entities. One of the unifying themes is the major contribution from the tumour microenvironment. Both the character of the neoplastic cells and the nature of the immune environment are critical to accurate diagnosis. Moreover, an understanding of the molecular alterations that characterize both the neoplastic cells and their microenvironment have led to therapeutic advances, targeting both neoplastic and reactive components. Other conditions may foster a similar inflammatory milieu and lead to lymphoproliferations that mimic the Hodgkin lymphomas. In this review we provide an update on the diagnostic features of the various subtypes and include additional information relevant for prognostic evaluation and investigation of potential therapeutic targets. Additionally, we also discuss those conditions that often cause confusion in diagnosis and need to be distinguished from the Hodgkin lymphomas.

Human Herpes Virus 6 (HHV-6)-associated Lymphadenitis: Pitfalls in Diagnosis in Benign and Malignant Settings.

Human herpes virus 6 (HHV-6) is a member of the ß-herpesvirinae subfamily. Most people acquire HHV-6 primary infection early in life and reactivation may occur, most often in immunocompromised individuals, leading to various clinical manifestations. HHV-6 infected cells may be identified in lymph nodes in both reactive and neoplastic conditions. Cases were retrieved from the hematopathology consultation service archives at National Institutes of Health from 2003 to 2017 in which infection by HHV-6 had been documented by immunohistochemical stains to HHV-6 gp60/110 envelope glycoprotein. Five cases of reactive lymphadenitis and 3 cases of lymphoma; 2 angioimmunoblastic T-cell lymphoma and 1 classic Hodgkin lymphoma, positive for HHV-6 were identified. The reactive lymph nodes showed marked paracortical hyperplasia and admixed large atypical lymphoid cells exhibiting pleomorphic nuclei, vesicular chromatin, and prominent eosinophilic intranuclear inclusions. Vascular proliferation and necrosis were also present, raising suspicion of peripheral T-cell lymphoma. The 3 cases of lymphoma showed similar viral inclusions, in addition to the characteristic features diagnostic of the lymphoma. Staining for HHV-6 was positive with a membranous and Golgi pattern and was restricted to cells with evident inclusions on hematoxylin and eosin. HHV-6 infected cells were positive for CD3 and CD4. HHV-6 lymphadenitis can present with morphologic atypia creating a diagnostic pitfall for lymphoma. In such cases, careful attention to the characteristic viral inclusions can lead to immunohistochemical analysis highlighting the replicating virus. In cases of lymphoma, identification of the inclusions is key in detecting the associated infection as well as in avoiding misinterpretation of the lymphoma subtype.

Crystal storing histiocytosis clinically mimicking metastatic carcinoma: Report of a case and reviews of literature.

BACKGROUND: Crystal storing histiocytosis (CSH) is a rare disorder characterized by accumulation of histiocytes containing crystalline material inclusions. This entity can be misdiagnosed as infection or tumor. We present a case of idiopathic CSH mimicking metastatic squamous cell carcinoma in a cervical lymph node and review of literature regarding this rare entity. METHODS AND RESULTS: The patient was a 70-year-old man with a medical history of squamous cell carcinoma of the right base of the tongue. The patient presented with an enlarged cervical lymph node, which was clinically diagnosed as metastatic carcinoma. At intraoperative consultation, it was unexpectedly discovered that the lymph node exhibited extensive histiocytosis containing crystal materials. Final pathology identified "crystal storing histiocytosis" because of amyloidal depositions. No metastatic carcinoma was seen. CONCLUSION: After 10 months of follow-up, the patient is disease free. To the best of our knowledge, this unusual clinical presentation is the first to describe CSH mimicking a metastatic carcinoma.

Glomerulopathy in a patient with sarcocystis infestation.

To date, sarcocystis has been considered an asymptomatic infection in humans. Even though cases with glomerulonephritis have been reported in animals with sarcocystis, there have been no reports of a similar occurrence in humans. We report a case of acute proliferative glomerulonephritis and leukocytoclastic vasculitis in a patient with sarcocystis infestation.