Germline Predisposition to Myeloid Neoplasms: Diagnostic Concepts and Classifications.

Molecular and sequencing advances have led to substantial breakthroughs in the discovery of new genes and inherited mutations associated with increased risk of developing myeloid malignancies. Many of the same germline mutated genes are also drivers of malignancy in sporadic cancer. Recognition of myeloid malignancy associated with germline mutations is essential for proper therapy, disease surveillance, informing related donor selection for hematopoietic stem cell transplantation, and genetic counseling of the patient and affected family members. Some germline mutations are associated with syndromic features that precede the development of malignancy; however, penetrance may be highly variable leading to masking of the syndromic phenotype and/or inherited etiology.

Aggressive non-Hodgkin lymphoma in the pediatric and young adult population; diagnostic and molecular pearls of wisdom.

Mature non-Hodgkin lymphomas (NHLs) of the pediatric and young adults(PYA), including Burkitt lymphoma (BL), diffuse large B cell lymphoma (DLBCL), high-grade B cell lymphoma (HGBCL), primary mediastinal large B cell lymphoma (PMBL) and anaplastic large cell lymphoma (ALCL), generally have excellent prognosis compared to the adult population. BL, DLBCL and HGBCL are usually of germinal center (GCB) origin in the PYA population. PMBL neither belongs to the GCB nor the activated B cell subtype and is associated with a poorer outcome than BL or DLBCL of comparable stage. Anaplastic large cell lymphoma is the most frequent peripheral T cell lymphoma occurring in the PYA and accounts for 10-15% of childhood NHL. Most pediatric ALCL, unlike in the adult, demonstrate expression of anaplastic lymphoma kinase (ALK). In recent years, the understanding of the biology and molecular features of these aggressive lymphomas has increased tremendously. This has led to reclassification of newer PYA entities including Burkitt-like lymphoma with 11q aberration. In this review, we will discuss the current progress discovered in frequently encountered aggressive NHLs in the PYA, highlighting the clinical, pathologic and molecular features that aid in the diagnosis of these aggressive lymphomas. We will be updating the new concepts and terminologies used in the new classification systems.

Diagnostic Flow Cytometry in the Era of Targeted Therapies: Lessons from Therapeutic Monoclonal Antibodies and Chimeric Antigen Receptor T-cell Adoptive Immunotherapy.

Therapeutic monoclonal antibodies (therapeutic mAb) and adoptive immunotherapy have become increasingly more common in the treatment of hematolymphoid neoplasms, with practical implications for diagnostic flow cytometry. Their use can reduce the sensitivity of flow cytometry for populations of interest owing to downregulation/loss of the target antigen, competition for the target antigen, or lineage switch. Expanded flow panels, marker redundancy, and exhaustive gating strategies can overcome this limitation. Therapeutic mAb have been reported to cause pseudo-light chain restriction, and awareness of this potential artifact is key. Established guidelines do not yet exist for antigen expression by flow cytometry for therapeutic purposes.

Isolated Light Chain-restricted Germinal Centers are Common in Follicular Hyperplasia by Ultrasensitive In Situ Hybridization.

Ultrasensitive bright-field RNA in situ hybridization (BRISH) can be used to detect lower levels of light chain expression than immunohistochemical stains or conventional colorimetric RNA in situ hybridization. In this study, we retrospectively reviewed 77 lymph node specimens with follicular hyperplasia and kappa/lambda BRISH performed as part of the diagnostic evaluation. Thirty-two of the specimens had ≥1 germinal center(s) (GC) showing light chain restriction (14 specimens with lambda-restricted GC, 9 with kappa-restricted GC, and 9 with separate kappa-restricted or lambda-restricted GC). In all but 1 specimen, the light chain-restricted GC represented a minority of the total GC (average: 10%, range: 0.2% to 60%). There was no significant difference in age, sex, type of biopsy (core vs. excision), number of GCs, proportion of cases with a light chain-restricted B-cell population by flow cytometry, or proportion of cases with a positive IgH gene rearrangement study between the specimens with and without restricted GCs. In our cohort of follicular hyperplasia cases, BRISH identified light chain-restricted GC more frequently than flow cytometry identified a monotypic B-cell population. Our findings highlight the potential for overinterpretation of light chain restriction in limited samplings such as fine needle aspiration cell blocks or core needle sampling and reinforce that interpretation of BRISH staining needs to occur in the context of the morphologic features including tissue architecture and results of additional immunohistochemical stains.

Overlapping Features of Primary Cutaneous Marginal Zone Lymphoproliferative Disorder and Primary Cutaneous CD4 + Small/Medium T-Cell Lymphoproliferative Disorder : A Diagnostic Challenge Examined by Genomic Analysis.

Primary cutaneous marginal zone lymphoproliferative disorder (PCMZL) and primary cutaneous CD4 + small/medium T-cell lymphoproliferative disorder (CD4 + TLPD) are indolent lymphoproliferative disorders. However, cases with overlapping features can be challenging. We identified 56 CD4 + TLPD and 38 PCMZL cases from our pathology archives. Clinical, morphologic, and immunophenotypic features were reviewed. Polymerase chain reaction for immunoglobulin (IG) and T-cell receptor gamma (TRG) gene rearrangements were analyzed. Next-generation sequencing studies were performed on 26 cases with adequate material, 19 with CD4 + TLPD, and 7 with PCMZL. CD4 + TLPD presented mostly (91%) as solitary lesions, located in the head and neck area (64%), while PCMZL occurred mostly in the upper extremity (47%) and trunk (34%). Lesions were sometimes multiple (40%) and recurrences (67%) were more common. Cases of PCMZL had an increase in reactive CD3 + T cells, with frequent programmed cell death protein 1 expression, whereas cases of CD4 + TLPD often contained abundant reactive B cells. Twenty-five cases were identified as having overlapping features: 6 cases of PCMZL were clonal for both IG and TRG; 11 cases of CD4 + TLPD were clonal for IG and TRG and 6 cases of CD4 + TLPD had light chain-restricted plasma cells. By next-generation sequencing, 23 variants were detected in 15 genes, with PCMZL more likely to show alterations, most commonly affecting TNFAIP3 and FAS, altered in 5 cases. Both entities have an indolent clinical course with response to conservative therapy and management, and warrant interpretation as a lymphoproliferative disorder rather than overt lymphoma.

The Effectiveness of Dual-Staining Immunohistochemistry in the Detection of Mantle Cell Lymphoma in the Bone Marrow.

OBJECTIVES: Immunohistochemistry (IHC) is a useful method for mantle cell lymphoma (MCL) detection in the bone marrow (BM). However, recognition of the neoplastic B cells can be challenging, especially when there is low-level disease. METHODS: We examined BM from 105 patients with MCL. IHC was performed using cyclin D1/CD79a and PAX5/CD5 dual stains, which were compared with single stains that included CD20, CD79a, cyclin D1, and CD5 and with multiparameter flow cytometry (FC). RESULTS: Based on the FC data, the overall sensitivity of the dual IHC stains was 95.6%. Both dual IHC stains showed better efficacy for detecting MCL cells compared with the aggregated single stains (P = .012). While three cases were positive by FC analysis but negative for dual staining, four cases showed cells positive for cyclin D1/CD79a and PAX5/CD5 dual staining that were not detected by FC. Two of these latter cases were in patients with minimal or focal disease involvement. CONCLUSIONS: Cyclin D1/CD79a and PAX5/CD5 dual IHC staining is an efficient procedure for the detection of MCL in the marrow and is particularly helpful in low-level or focal involvement by MCL. This approach can be particularly useful when marrow aspirates are inadequate or unavailable.

Benign and malignant hematologic manifestations in patients with VEXAS syndrome due to somatic mutations in UBA1.

Somatic mutations in UBA1 involving hematopoietic stem and myeloid cells have been reported in patients with the newly defined VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Here, we report clinical hematologic manifestations and unique bone marrow (BM) features in 16 patients with VEXAS. All patients were male and had a history of severe autoinflammatory and rheumatologic manifestations and a somatic UBA1 mutation (p.Met41). Ten patients had hematologic disorders: myelodysplastic syndrome (MDS; 6 of 16), multiple myeloma (2 of 16), monoclonal gammopathy of undetermined significance (2 of 16), and monoclonal B-cell lymphocytosis (2 of 16), and a few of those patients had 2 co-existing clonal processes. Although macrocytic anemia (100%) and lymphopenia (80%) were prevalent in all patients with VEXAS, thrombocytopenia and neutropenia were more common in patients with progression to MDS. All BMs in VEXAS patients had prominent cytoplasmic vacuoles in myeloid and erythroid precursors. In addition, most BMs were hypercellular with myeloid hyperplasia, erythroid hypoplasia, and varying degrees of dysplasia. All patients diagnosed with MDS were lower risk (low blast count, very good to intermediate cytogenetics) according to standard prognostic scoring with no known progression to leukemia. In addition, 10 of 16 patients had thrombotic events, including venous thromboembolism and arterial stroke. Although VEXAS presents symptomatically as a rheumatologic disease, morbidity and mortality are associated with progression to hematologic disease. Given the increased risk of developing MDS and multiple myeloma, surveillance for disease progression is important.

Concurrent chronic lymphocytic leukemia/small lymphocytic lymphoma and hairy cell leukemia: clinical, pathologic and molecular features.

Simultaneous occurrence of hairy cell leukemia (HCL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (termed CLL) is very rare. Clinical characteristics, pathology and management of these cases have not been well described. We present six patients with CLL and HCL or HCL variant (HCL-v). Of six patients, three were initially diagnosed with CLL and later developed concurrent HCL. Two patients had concurrent HCL or HCL-v and CLL at initial diagnosis. One had HCL first, followed by concurrent CLL. Polymerase chain reaction analysis demonstrated B-cell clonality in all cases, with two distinct clonal populations in four cases, and three clonal populations in one case. Five patients were treated with a combination of a purine analog such as fludarabine, cladribine, and pentostastin with either rituximab or ibrutinib, while one received dabrefenib and trametinib. All patients achieved a durable response to either CLL or HCL-directed therapy with reduction or ablation of coexisting B-cell clones.

Well differentiated arginase-1 negative hepatocellular carcinoma.

BACKGROUND: The diagnosis of hepatocellular carcinoma (HCC) is dependent on the histologic and immunohistochemical analysis of biopsy and resection specimens. The distinction of HCC from metastatic neoplasms is pertinent for treatment and prognostic purposes. Arginase-1 (Arg-1), a marker of hepatocellular differentiation, has shown superior sensitivity and specificity when compared to other immunohistochemical markers of detection of HCC such as hepatocyte paraffin antigen (HepPar-1). Studies have shown that poorly differentiated HCC can lose arginase expression, however well differentiated HCC are rarely ever arginase negative. METHODS: In this study Arg-1 expression was detected using immunohistochemical staining on tissue specimens from 40 confirmed cases of well differentiated HCC specimens using a highly specific monoclonal antibody for Arg-1. Specificity of the Arg-1 antibody was evaluated by immunostaining of 24 non-HCC tumors in the liver and 200 non-liver neoplasms using paraffin block and tissue micro-array (TMA) based immunohistochemistry. RESULTS: Four well differentiated HCC cases were found to be completely negative for Arg-1 and similarly all 224 non-HCC tumors did not express Arg-1. The arginase negative well differentiated tumors were positive for other hepatocellular markers such as HepPar-1 and polyclonal carcinoembryonic antigen (pCEA). Of the four tumors, only one recurred at 28 months. All patients are currently stable with a mean survival of 43 months. CONCLUSIONS: Arg-1 negative well differentiated HCC can be a clinical dilemma which can lead to misdiagnosis. Confirmation with other hepatocellular markers such as HepPar1 and pCEA is essential in making the correct diagnosis. The clinicopathologic outcomes of arginase negative well differentiated HCC has been poorly characterized, thus our findings are of utmost importance in understanding the clinical behavior of these tumors. This may have a potential role in understanding the mechanism of the use of targeted therapy in HCC tumors.

Clear cell sarcoma in unusual sites mimicking metastatic melanoma.

BACKGROUND: Clear cell sarcoma is an aggressive rare malignant neoplasm with morphologic and immunohistochemical similarities to malignant melanoma. Both disease entities display melanin pigment and melanocytic markers, making differentiation between the two difficult. Although clear cell sarcoma cases in the literature have mainly involved deep soft tissues of the extremities, trunk or limb girdles, we report here two cases of primary clear cell sarcoma in unusual sites and describe their clinicopathologic findings. CASE SUMMARY: The first case involves a 37-year-old female, who presented with jaw pain and a submandibular mass. The second case involves a 33-year-old male, who presented with back pain and a thoracic spine tumor. Both cases showed tumors with diffuse infiltration of neoplastic cells that were positive for melanocytic markers, and in both cases this finding led to an initial diagnosis of metastatic melanoma. However, further analysis by fluorescence in situ hybridization (commonly known as FISH) showed a rearrangement of the EWS RNA binding protein 1 (EWSR1) gene on chromosome 22q12 in both patients, confirming the diagnosis of clear cell sarcoma. CONCLUSION: Distinction between clear cell sarcoma and malignant melanoma can be made by FISH, particularly in cases of unusual tumor sites.

Prognostic Implications of Arginase and Cytokeratin 19 Expression in Hepatocellular Carcinoma After Curative Hepatectomy: Correlation With Recurrence-Free Survival.

BACKGROUND: The prognostic value of arginase expression in hepatocellular carcinoma (HCC) has been evaluated previously. However, no clear distinction exists yet on the role of arginase-1 as a predictor of recurrence in HCC. Cytokeratin 19 (CK19), a cholangiocytic marker, is occasionally expressed in HCC, but the combination of arginase-1 and CK19 expression has never been evaluated. The aim of the study was to investigate the usefulness of arginase-1 and CK19 expression alone and in combination for prognosticating HCC tumor recurrence after surgical resection. METHODS: Tissue sections from 112 HCCs were immunostained using an automated method and the mouse monoclonal arginase-1 and mouse monoclonal CK19 antibodies. The clinicopathologic variables, including alpha-fetoprotein levels, viral hepatitis, cirrhosis, tumor size, grade and number, vascular invasion, tumor-node-metastasis (TNM) stage, and tumor recurrence and survival, were obtained from each patient's medical records. The variables were assessed for correlation with the immunochemical results. Comparisons of recurrence-free and overall survival were performed using univariate and multivariate regression analyses. A P-value of ≤ 0.05 was considered statistically significant. RESULTS: High arginase-1 expression was detected in the HCCs of 93 patients (83%), whereas CK19 was positive in the HCCs of only 19 patients (17%). In the univariate analyses, CK19 positivity in HCC was associated with decreased recurrence-free survival compared with CK19-negative HCC (P = 0.0002). Arginase-1 expression was associated with decreased recurrence-free survival when patients were stratified over advanced TNM stage and presence of vascular invasion. The combination of arginase-1 and CK19 expression was a better predictor of decreased recurrence-free survival (P = 0.00008). Arginase-1/CK19 expressions when combined with multiple tumors, TNM stage and vascular invasion were also associated with decreased recurrence-free survival. In the multivariate analysis, tumor grade, CK19 and arginase-1/CK19 expressions were identified as independent prognostic indicators for decreased recurrence-free survival. CONCLUSION: Arginase-1 and CK19 combination immunoreactivity is a potential biomarker of adverse prognosis in HCC, correlating with the presence of multiple tumors, vascular invasion and advanced stage.

Radiation-induced astrocyte senescence is rescued by Δ133p53.

BACKGROUND: Cellular senescence and the senescence-associated secretory phenotype (SASP) may contribute to the development of radiation therapy-associated side effects in the lung and blood vessels by promoting chronic inflammation. In the brain, inflammation contributes to the development of neurologic disease, including Alzheimer's disease. In this study, we investigated the roles of cellular senescence and Δ133p53, an inhibitory isoform of p53, in radiation-induced brain injury. METHODS: Senescent cell types in irradiated human brain were identified with immunohistochemical labeling of senescence-associated proteins p16INK4A and heterochromatin protein Hp1γ in 13 patient cases, including 7 irradiated samples. To investigate the impact of radiation on astrocytes specifically, primary human astrocytes were irradiated and examined for expression of Δ133p53 and induction of SASP. Lentiviral expression of ∆133p53 was performed to investigate its role in regulating radiation-induced cellular senescence and astrocyte-mediated neuroinflammation. RESULTS: Astrocytes expressing p16INK4A and Hp1γ were identified in all irradiated tissues, were increased in number in irradiated compared with untreated cancer patient tissues, and had higher labeling intensity in irradiated tissues compared with age-matched controls. Human astrocytes irradiated in vitro also experience induction of cellular senescence, have diminished Δ133p53, and adopt a neurotoxic phenotype as demonstrated by increased senescence-associated beta-galactosidase activity, p16INK4A, and interleukin (IL)-6. In human astrocytes, Δ133p53 inhibits radiation-induced senescence, promotes DNA double-strand break repair, and prevents astrocyte-mediated neuroinflammation and neurotoxicity. CONCLUSIONS: Restoring expression of the endogenous p53 isoform, ∆133p53, protects astrocytes from radiation-induced senescence, promotes DNA repair, and inhibits astrocyte-mediated neuroinflammation.

Incidental Metastatic Meningioma Presenting as a Large Liver Mass.

Meningiomas are slow growing neoplasms of the central nervous system (CNS). Most of the tumors are benign and distant metastasis from a benign meningioma is rare. Metastasis to the liver, although rare, usually presents with hypoglycemia or occurs in conjunction with a clinical history of an intracranial meningioma or following the resection of a prior CNS meningioma, thus making clinical diagnosis relatively easy. Here we present an unusual case of metastatic meningioma to the liver in a 54-year-old female who presented with an incidental liver mass by ultrasound. Her clinical history and physical examination were unremarkable. A partial hepatectomy revealed a meningioma on histology. Further investigation by imaging studies showed a frontal parasagittal dural mass which was confirmed to be a World Health Organization (WHO) grade 1 meningioma. To our knowledge, this is the first report of a clinically silent metastatic meningioma to the liver without either a concurrent or a previous history of meningioma. Precise diagnosis of this challenging case requires high clinical suspicion, histopathology, and immunohistochemistry.

Intravascular Large B-Cell Lymphoma Mimicking Temporal Arteritis.

Intravascular lymphoma is a rare type of lymphoma, characterized by growth of lymphoma cells within the microvasculature. The majority of the cases are of B-cell lineage, although rare examples of T or NK lineage have also been reported. The lymphoma is usually widely disseminated in the vascular spaces of any organ at the time of diagnosis including the skin and bone marrow. Lymph nodes are typically spared. The clinical picture depends on the specific organ involvement making the correct diagnosis very difficult. Here, we report a case of intravascular large B-cell lymphoma diagnosed postmortem on a 69-year-old African-American male who presented with unilateral proptosis and visual loss. An initial diagnosis of temporal arteritis was made and the patient received corticosteroids. However, the patient developed multiorgan failure and expired. On autopsy, there was disseminated intravascular lymphoma involving predominantly vessels within the heart, kidneys, liver, stomach, lungs, adrenal glands, small intestine, bladder, thyroid, and brain. Interestingly, there was also partial involvement of the retroperitoneal lymph nodes which is an unusual presentation in this disorder. Immunohistochemical staining showed that the lymphoma cells were positive for CD20, indicating B-cell phenotype. This case supports the "mimicking nature" of this rare entity with an unusual presentation with proptosis and visual loss, simulating temporal arteritis and a rare involvement of the retroperitoneal lymph nodes. The presentation of intravascular large B-cell lymphoma can vary, and the key to diagnosis is dependent on histopathology and immunohistochemistry. Increased awareness, early tissue diagnosis, and prompt chemotherapy are crucial for this otherwise lethal disease.

The Clinicopathologic Spectrum of IgG4-Related Disease

Immunoglobulin G4-related disease is a fibroinflammatory systemic disease that is characterized by focal or diffuse organ infiltration by immunoglobulin G4-bearing plasma cells. Immunoglobulin G4-related disease may affect any organ, and a high index of suspicion is necessary for early detection to avoid irreversible fibrosis, organ dysfunction, and death. Tumor-forming lesions are common radiological features of immunoglobulin G4-related disease that need to be differentiated from malignancies. The diagnostic approach requires the integration of clinical, biochemical, and radiographic manifestations with classic histopathologic features, which remain crucial to diagnosis. The histology of immunoglobulin G4-related disease is determined by a dense lymphoplasmacytic infiltrate, storiform fibrosis, and obliterative phlebitis in the presence of increased immunoglobulin G4-positve plasma cells. Although immunoglobulin G4-related disease forms a distinct, clinically independent disease category, many questions and problems remain unanswered, especially on its pathogenesis and the role of immunoglobulin G4. Advances in the understanding of immunoglobulin G4-related disease are likely to change the diagnostic approach in the future and create potential targets for therapeutic purposes. Here we describe the concept of immunoglobulin G4-related disease and the most recent knowledge in the clinico-pathological characteristics on this emerging disease. This study can guide clinicians in early diagnosis and prevent unnecessary surgical resections.

Myeloid sarcoma with megakaryoblastic differentiation presenting as a breast mass.

Myeloid sarcoma is an extramedullary tumor that consists of myeloblasts or immature myeloid cells. The neoplasm can occur in any part of the body, including the bone, periosteum, lymph nodes, skin, and soft tissue and they may occur de novo or in association with acute myeloid leukemia, myeloproliferative neoplasms and myelodysplastic syndromes. Most cases display a myelomonocytic or pure monoblastic morphology. Tumors with megakaryoblastic differentiation are extremely uncommon and may occur in association with transformation of a myeloproliferative disorder. Myeloid sarcoma presenting as a breast mass is very rare and diagnostically challenging. We report a case of myeloid sarcoma with megakaryoblastic differentiation in the breast of a patient with history of essential thrombocythemia. The mass was composed of undifferentiated pleomorphic malignant cells in trabecular cords and nests with many scattered giant malignant cells and brisk abnormal mitoses. On immunohistochemistry, the neoplastic cells were positive for CD61, CD31, CD34, Factor VIII and CD43 which confirmed the diagnosis. To our knowledge, this is the first report of myeloid sarcoma with megakaryoblastic morphology occurring in the breast. Here we discuss the clinicopathologic features of this rare entity and the challenges involved in making this difficult diagnosis.

Synchronous Leydig Cell Tumor and Seminoma in the Ipsilateral Testis.

Leydig cell tumor is a rare sex cord tumor that accounts for 1-3% of all testicular neoplasms. Seminomas are more common and occur in 30-40% of testicular tumors. Leydig cell tumors are derived from undifferentiated gonadal mesenchyme and the concurrent development of the tumor and a seminoma which are derived from germinal epithelium in an ipsilateral testis is extremely rare. Here we report a case of ipsilateral Leydig cell tumor and seminoma occurring in a 38-year-old man with a left testicular mass. The key to diagnosis is dependent on histopathology and immunohistochemistry. To our knowledge, this is the first diagnosis of the two disease entities in a unilateral testis using immunohistochemistry. Increased awareness of the entity is important in order to distinguish Leydig cell tumor and seminomas from other malignancies due to difference in therapeutic management.