Syphilis in Hematopathology Practice: A Diagnostic Challenge.

CONTEXT.­: Syphilis, a reemerging disease caused by spirochete Treponema pallidum, is becoming more frequent in surgical pathology and hematopathology practices. Hematopathologists typically receive lymph node biopsies from patients with syphilis who have localized or diffuse lymphadenopathy. Occasionally, syphilis infection in the aerodigestive tract can show a prominent lymphoplasmacytic infiltrate and mimic lymphoma. Besides the varying and occasional atypical morphology, the fact that clinical suspicion tends to be low or absent when histologic evaluation is requested adds to the importance of making this diagnosis. OBJECTIVE.­: To summarize histologic features of syphilitic lymphadenitis and syphilis lesions in the aerodigestive tract, and to review differential diagnosis and potential diagnostic pitfalls. DATA SOURCES.­: Literature review via PubMed search. CONCLUSIONS.­: Characteristic histologic findings in syphilitic lymphadenitis include thickened capsule with plasma cell-rich inflammatory infiltrate, reactive follicular and paracortical hyperplasia with prominent lymphoplasmacytic infiltrate, and vasculitis. Lymph nodes, however, can show a number of other nonspecific histologic features, which frequently makes the diagnosis quite challenging. In the aerodigestive tract, syphilis is characterized by plasma cell-rich infiltrates. Immunohistochemistry for T pallidum is the preferred method for detecting spirochetes; however, this immunohistochemical stain shows cross-reactivity with other treponemal and commensal spirochetes. Differential diagnosis of syphilis in lymph nodes and the aerodigestive tract is broad and includes reactive, infectious, and neoplastic entities. Pathologists should be aware of the histologic features of syphilis and keep this challenging entity in the differential diagnosis.

High-grade B-cell lymphoma with concurrent MYC rearrangement and 11q aberrations: clinicopathologic, cytogenetic, and molecular characterization of 4 cases.

High-grade B-cell lymphoma with 11q aberrations (LBL-11q) resembles Burkitt lymphoma (BL), is negative for MYC rearrangement, and harbors chromosome 11q aberrations. Rare cases of high-grade B-cell lymphoma with concurrent MYC rearrangement and 11q aberrations (HGBCL-MYC-11q) have been described. In this study, we report the clinicopathologic, cytogenetic, and molecular findings in 4 such cases. Diagnoses were made on tissue or bone marrow biopsies. Karyotype, fluorescence in situ hybridization, genomic microarray analyses, and next-generation sequencing were performed. All patients were male (median age, 39 years). Three cases were diagnosed as BL, while one was diagnosed as diffuse large B-cell lymphoma. Karyotypes (available in 2 patients) were complex. In 1 patient, copy number analysis showed gains at 1q21.1-q44 and 13q31.3 and loss of 13q34, abnormalities typically seen in BL. All of our cases showed 2 or more mutations that are recurrent in BL, including ID3, TP53, DDX3X, CCND3, FBXO1, and MYC. Two cases showed a GNA13 mutation, commonly seen in LBL-11q. Cases of HGBCL-MYC-11q display overlapping morphologic and immunophenotypic, as well as cytogenetic and molecular features between BL and LBL-11q, with a mutational landscape enriched for mutations recurrent in BL. Concurrent MYC rearrangement with 11q abnormalities is important to recognize, especially as it has implications for their classification.

Low T-cell proportion in the tumor microenvironment is associated with immune escape and poor survival in diffuse large B-cell lymphoma.

The tumor microenvironment (TME) is important in the pathogenesis and prognosis of lymphoma. Previous studies have demonstrated that features of the diffuse large B-cell lymphoma (DLBCL) TME can be associated with prognosis, but questions remain about the mechanisms underlying these TME features, and the interplay between tumor cells and the local TME. Therefore, we performed multispectral immunofluorescence (mIF) using two 6-color panels to interrogate the cellular proportions of T-cell subsets, macrophages, and natural killer cells in 57 cases of de novo DLBCL treated with R-CHOP chemotherapy. We found that very low CD3+ T-cell proportion and low CD4+PD1+ and CD8+PD1+ T cells have poor survival compared to those with a high T-cell proportion. Also, cases with concurrently low TIM3 and PD1 have a poor prognosis. This poor prognosis with low T-cell proportion was validated using immune deconvolution of gene expression profiling data from 351 cases of DLBCL and an additional cohort of 53 cases of DLBCL using routine immunohistochemistry. In addition, cases with loss of B2M, HLA I and/or HLA II protein expression on the tumor cells also had a low T-cell proportion, providing evidence that lack of these proteins allows for immune evasion. Overall, our results show that patients with DLBCL with a low T-cell proportion in the TME have a poor survival when treated with R-CHOP and exhibit mechanisms of immune escape.

Fibrin-Associated, EBV-Negative Diffuse Large B-Cell Lymphoma Arising in Atrial Myxoma: Expanding the Spectrum of the Entity.

Fibrin-associated diffuse large B-cell lymphoma (FA-DLBCL) is a provisional entity in the 2017 Revision of the World Health Organization Classification. This indolent entity, which is frequently discovered incidentally, is currently classified under the category of diffuse large B-cell lymphoma associated with chronic inflammation (DLBCL-CI), an aggressive lymphoma with poor survival. Several authors have proposed that it be classified separately since, in contrast to DLBCL-CI, transformation to aggressive lymphoma has rarely been reported and this entity has distinct clinical and histological features. We describe a rare case of a 62-year-old male with FA-DLBCL associated with atrial myxoma, which was incidentally discovered. In contrast to typically described immunophenotypic features of this entity, that is, activated B-cell phenotype (ABC) and Epstein-Barr virus (EBV) positivity, our case showed germinal center B-cell (GCB) phenotype and was EBV negative. Clinical staging revealed no evidence of lymphoma elsewhere in the body, and the patient did not receive adjuvant chemotherapy after surgical excision and remains in remission. This case illustrates that occasionally FA-DLBCL can show GCB phenotype, as opposed to the typical ABC phenotype. Moreover, we propose that the definition of the entity be expanded to include EBV-negative cases.

Classic Hodgkin Lymphoma - Old Disease, New Directions: An Update on Pathology, Molecular Features and Biological Prognostic Markers.

The aim of this paper is to review morphologic, immunophenotypic, and molecular features of classic Hodgkin lymphoma, as well as different prognostic markers in this neoplasm. Classic Hodgkin lymphoma (CHL) accounts for 15-25% of all lymphomas in the Western world. The hallmark of this disease is the neoplastic Hodgkin/Reed-Sternberg (HRS) cell, which is favored to be derived from germinal center B-cells but has lost many of the B-cell markers. HRS cells are scattered within a dense inflammatory infiltrate, and through a network of cytokines and chemokines they shape their microenvironment, evade immune response, survive, and grow. In the last two decades multiple prognostic markers related to HRS cells, the microenvironment or both, have been evaluated in patients with CHL. They include clinical, immunohistochemical, cytogenetic, and molecular markers that can predict survival and identify high-risk patients who will likely relapse after therapy. More recently, circulating tumor DNA analysis by next-generation sequencing has opened new avenues for diagnosis and disease monitoring after therapy. The increased understanding of molecular mechanisms underlying CHL pathogenesis has led to successful implementation of novel therapies, such as anti-PD-1 antibodies, which are becoming a mainstay of treatment in relapsed/refractory patients. CONCLUSION: Currently, pathologic prognostic markers are not routinely assessed at initial diagnosis of CHL. However, as more therapies become available, it will be important to identify patients with high-risk disease who may benefit from more intense or targeted therapy upfront.

Relative frequency and clinicopathologic characteristics of MYC-rearranged follicular lymphoma.

MYC rearrangement is a relatively rare genetic abnormality in follicular lymphoma (FL). In this study, we evaluated the relative frequency of MYC rearrangement in 522 cases of FL and studied their clinicopathologic, cytogenetic, and molecular characteristics. Fluorescence in situ hybridization studies for MYC (break-apart probe), MYC/IGH, IGH/BCL2, and BCL6 rearrangements were performed on tissue microarrays. Immunohistochemical stains for CD10, BCL2, BCL6, and MYC were performed and scored on MYC-rearranged cases. On 4 FL cases, a custom targeted panel of 356 genes was used for mutation analysis. Ten cases (1.9%) were positive for MYC rearrangement. Histologically, 6 of 10 cases were grade 1-2, and 4 cases were grade 3A. By immunohistochemistry, 9 of 9 tested cases were CD10+, all cases were BCL6+, and 9/10 cases were BCL2+. MYC protein staining was low in all cases tested. IGH/BCL2 rearrangement was detected in 5 of 9 cases, whereas BCL6 rearrangement was detected in 3 of 7 tested cases and 4 of 10 cases showed MYC/IGH rearrangement. The most commonly detected mutations in the MYC-positive cases included HLA-B, TNFRSF14, and KMT2D. MYC and/or B2M abnormalities were detected in 2 cases. In conclusion, MYC rearrangement is uncommon in FL and these cases do not appear to have specific histologic characteristics. Molecular analysis showed abnormalities in genes associated with transformation, namely MYC and B2M. Larger studies are needed to evaluate if MYC-rearrangement in FL has prognostic significance.

Validation of the Double-Hit Gene Expression Signature (DLBCL90) in an Independent Cohort of Patients with Diffuse Large B-Cell Lymphoma of Germinal Center Origin.

The prognosis of diffuse large B-cell lymphoma (DLBCL) has been associated with clinical parameters, cell of origin, and various genetic aberrations. Recently, a NanoString gene expression assay (DLBCL90) was developed, which identifies DLBCL cases with an outcome similar to those with double- or triple-hit DLBCL with both MYC and BCL2 rearrangements. This study validates the predictive ability of the DLBCL90 assay in an independent cohort of patients with the germinal center B-cell subtype DLBCL. A customized targeted sequencing panel was used to analyze the mutational profile in these patients. Cases with a double or triple hit by conventional fluorescence in situ hybridization cytogenetic analysis are known to have a poor prognosis, and the DLBCL90 gene expression signature identified these cases, as well as additional cases that would have otherwise been missed by fluorescence in situ hybridization analysis. Our findings validate use of the DLBCL90 assay for identifying high-risk patients for new and innovative therapies.

Double-hit Signature with TP53 Abnormalities Predicts Poor Survival in Patients with Germinal Center Type Diffuse Large B-cell Lymphoma Treated with R-CHOP.

PURPOSE: We performed detailed genomic analysis on 87 cases of de novo diffuse large B-cell lymphoma of germinal center type (GCB DLBCL) to identify characteristics that are associated with survival in those treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone). EXPERIMENTAL DESIGN: The cases were extensively characterized by combining the results of IHC, cell-of-origin gene expression profiling (GEP; NanoString), double-hit GEP (DLBCL90), FISH cytogenetic analysis for double/triple-hit lymphoma, copy-number analysis, and targeted deep sequencing using a custom mutation panel of 334 genes. RESULTS: We identified four distinct biologic subgroups with different survivals, and with similarities to the genomic classifications from two large retrospective studies of DLBCL. Patients with the double-hit signature, but no abnormalities of TP53, and those lacking EZH2 mutation and/or BCL2 translocation, had an excellent prognosis. However, patients with an EZB-like profile had an intermediate prognosis, whereas those with TP53 inactivation combined with the double-hit signature had an extremely poor prognosis. This latter finding was validated using two independent cohorts. CONCLUSIONS: We propose a practical schema to use genomic variables to risk-stratify patients with GCB DLBCL. This schema provides a promising new approach to identify high-risk patients for new and innovative therapies.

Sarcomas of the mediastinum with epithelioid morphology.

While soft tissue sarcomas typically have a spindled or pleomorphic appearance, a subset of malignant soft tissue neoplasms can have a prominent epithelioid morphology. In complex anatomic sites such as the mediastinum, such tumors can often be mistaken for a carcinoma or mesothelioma. Frequent expression of cytokeratin staining can further confound the diagnostic process and familiarity with these entities can help prevent an erroneous diagnosis. Particular entities that have been reported to occur in the mediastinum with such features include dedifferentiated liposarcoma, pleomorphic liposarcoma, malignant peripheral nerve sheath tumor, synovial sarcoma, SMARCA4-deficient thoracic sarcoma, alveolar soft part sarcoma and clear cell sarcoma. Many of these tumors exhibit unique clinical, genetic, molecular or immunohistochemical features which allow for accurate characterization. For example, pleomorphic liposarcoma contains bizarre appearing lipoblasts and dedifferentiated liposarcoma exhibits MDM2 gene amplification that is typically confirmed by fluorescence in-situ hybridization. Malignant peripheral nerve sheath tumor will often arise in association with a nerve or neurofibroma. Synovial sarcoma consistently exhibits rearrangements involving the SS18 gene and SMARCA4-deficient thoracic sarcoma shows loss of SMARCA4 staining in the tumor cells. Alveolar soft part sarcoma demonstrates an ASPL-TFE3 fusion transcript. Clear cell sarcoma often shows an EWSR1-ATF1 fusion transcript. When encountering a sarcoma of the mediastinum with epithelioid features, familiarity with these and other characteristics can help insure a correct diagnosis.

Disease Progression in a Patient With Indolent T-Cell Lymphoproliferative Disease of the Gastrointestinal Tract.

Indolent T-cell lymphoproliferative disorder (T-LPD) of the gastrointestinal (GI) tract is a new provisional entity in the 2016 revision of the World Health Organization classification. The disease has an indolent course and progression to aggressive T-cell lymphoma has rarely been reported. We describe a case of a 37-year-old male with indolent T-LPD of the GI tract who 3 years later developed aggressive T-cell lymphoma and died of progressive disease. An infiltrate of indolent T-LPD in the GI tract and aggressive lymphoma diagnosed from the liver biopsy had similar immunophenotype, but cellular infiltrate in the liver showed more atypia compared with the GI biopsies of indolent T-LPD. Moreover, T-cell gene rearrangement studies showed an identical clonal rearrangement in indolent T-LPD and aggressive lymphoma. Patients with indolent T-LPD of the GI tract need a long-term follow-up, as some of them may develop more aggressive lymphoma.

Kikuchi-Fujimoto Disease: A Review.

Kikuchi-Fujimoto disease (KFD) is a rare entity characterized by subacute necrotizing lymphadenopathy and frequently associated with fever. Young adults of Asian ancestry are most commonly affected, but it has been reported worldwide. Despite many studies in the literature, the cause of KFD remains uncertain. Histologically, KFD is characterized by paracortical lymph node expansion with patchy, well-circumscribed areas of necrosis showing abundant karyorrhectic nuclear debris and absence of neutrophils and eosinophils. Three evolving histologic patterns-proliferative, necrotizing, and xanthomatous-have been recognized. By immunohistochemistry, histiocytes in KFD are positive for myeloperoxidase. There is a marked predominance of T cells in the lesions (with mostly CD8-positive cells) with very few B cells. The differential diagnosis of KFD includes infectious lymphadenitis, autoimmune lymphadenopathy (primarily systemic lupus erythematosus), and lymphoma. Clinicians and pathologists are poorly familiar with this entity, which frequently causes significant diagnostic challenges.

Follicular Lymphoma Diagnostic Caveats and Updates.

CONTEXT.­: Follicular lymphoma is a common small B-cell lymphoma, likely to be encountered by any practicing pathologist, regardless of specialty. Although the features of typical follicular lymphoma are well known and in most instances easily identifiable, there are lesser-appreciated morphologic appearances that can raise alternative diagnostic possibilities. The limited tissue available in core needle biopsies can make it additionally challenging to thoroughly evaluate those features in the context of architecture. Furthermore, ancillary testing including immunohistochemistry and molecular/genetic analysis do not always show classic findings and may pose additional challenges to interpretation. OBJECTIVES.­: To review the morphologic features of follicular lymphoma with a discussion of morphologic variants and mimics; to discuss pitfalls of ancillary testing and provide the practicing pathologist with an appropriate context for interpretation of immunohistochemical and molecular/genetic studies when follicular lymphoma is part of the differential diagnosis; and to propose diagnostic strategies when there is limited tissue for evaluation. DATA SOURCES.­: We used examples of follicular lymphoma from our institution as well as a review of the literature, with a focus on the diagnostic aspects that are broadly relevant to a general pathology practice. CONCLUSIONS.­: Follicular lymphoma can occasionally present with atypical morphologic, immunohistochemical, or molecular/genetic features. In particular, those findings can be difficult to interpret in the setting of a limited tissue sample. Awareness of those possibilities will help guide the pathologist to a more accurate and precise diagnosis.

Frequency of MYD88 and CD79B mutations, and MGMT methylation in primary central nervous system diffuse large B-cell lymphoma.

Primary CNS diffuse large B-cell lymphoma (PCNS-DLBCL) and systemic DLBCL harbor mutations in MYD88 and CD79B. DNA methyltransferase (MGMT) is methylated in some DLBCL. Our goal was to investigate the frequencies of these events, which have not been previously reported within the same series of patients with PCNS-DLBCL. Fifty-four cases of PCNS-DLBCL from two institutions were analyzed by Sanger sequencing for MYD88 and CD79B, and pyrosequencing for MGMT. MYD88 mutations were identified in 68.8% (35 of 51 cases), with L265P being the most frequent mutation. Mutations other than L265P were identified in 21.6% of cases, of which eight novel MYD88 mutations were identified. Of mutated cases, 17.6% had homozygous/hemizygous MYD88 mutations, which has not been previously reported in PCNS-DLBCL. CD79B mutations were found in six of 19 cases (31.6%), all in the Y196 mutation hotspot. MGMT methylation was observed in 37% (20 of 54 cases). There was no significant difference in median overall survival (OS) between the wild type and mutated MYD88 cases, or between methylated and unmethylated MGMT cases. However, a significant difference (P = 0.028) was noted in median OS between the wild type and mutated CD79B cases.

Cytopenias and clonal expansion of gamma/delta T-cells in a patient with anaplasmosis: a potential diagnostic pitfall.

Human granulocytic anaplasmosis is a rare, tick-borne infectious disease caused by Anaplasma phagocytophilum. Herein, we report a rare case of human granulocytic anaplasmosis associated with cytopenias and clonal expansion of gamma/delta T-cells in the bone marrow. A 77-year old man presented multiple times to the emergency department complaining of muscle weakness. Complete blood count detected cytopenias and peripheral blood smear showed pseudo Pelger-Huet neutrophils. These findings prompted bone marrow evaluation with ancillary studies including flow cytometry, karyotyping and T-cell rearrangement studies. Careful examination of peripheral blood smear revealed very rare neutrophils with intracytoplasmic inclusions, suggestive of ehrlichiosis/anaplasmosis. Bone marrow evaluation showed dyserythropoiesis, dysmegakaryopoiesis and prominence of hemophagocytic histiocytes. Furthermore, an increased number of T-cells was seen in the bone marrow and flow cytometry showed excess of gamma/delta T-cells, while T-cell rearrangement studies detected a T-cell clone. Serologic evaluation confirmed the diagnosis of anaplasmosis. This case nicely illustrates hematologic sequelae of infection with Anaplasma and potential diagnostic pitfalls, such as myelodysplastic syndrome and T-cell lymphoproliferative disorder. To our knowledge, this is the first reported case of clonal expansion of gamma/delta T-cells associated with anaplasmosis. Pathologists should be careful and vigilant when screening peripheral blood smears, as they are often the first to raise the suspicion of anaplasmosis.

Non-Hodgkin lymphoma in Romania: a single-centre experience.

Epidemiologic studies of non-Hodgkin lymphoma (NHL) in Eastern Europe are scarce in the literature. We report the experience of the "Ion Chiricuta" Institute of Oncology in Cluj-Napoca (IOCN), Romania, in the diagnosis and outcome of patients with NHL. We studied 184 consecutive NHL patients diagnosed in the Pathology Department of IOCN during the years 2004-2006. We also obtained epidemiological data from the Northwestern (NW) Cancer Registry. In the IOCN series, the most common lymphoma subtype was diffuse large B-cell lymphoma (43.5%), followed by the chronic lymphocytic leukaemia/small lymphocytic lymphoma (21.2%). T-cell lymphomas represented a small proportion (8.2%). The median age of the patients was 57 years, with a male-to-female ratio of 0.94. Patients with indolent B-cell lymphomas had the best overall survival, whereas those with mantle cell lymphoma had the worst survival. The NW Cancer Registry data showed that the occurrence of NHL in the NW region of Romania was higher in men [world age-standardized incidence rate/100 000 (ASR)-5.9; 95% CI 5.1-6.6] than in women (ASR-4.1; 95% CI 3.5-4.7) with age-standardized male-to-female ratio of 1.44 (p = 0.038). Chronic lymphocytic leukaemia/small lymphocytic lymphoma was the most common NHL in the NW region of Romania, accounting for 43% of all cases, followed by diffuse large B-cell lymphoma (36%). The 5-year, age-standardized cumulative relative survival for NHL in the County of Cluj in NW Romania, for the period of 2006-2010, was 51.4%, with 58.4% survival for men and 43.2% for women. Additional studies of NHL in Eastern Europe are needed. Copyright © 2015 John Wiley & Sons, Ltd.

Multifocal brain involvement in a patient with hairy cell leukemia successfully treated with rituximab and cladribine.

Brain involvement, although rare, can occur in HCL.The combination of cladribine and rituximab is a highly effective treatment of HCL with brain involvement.

Atypical cells in a voided urine cytology specimen in a renal transplant recipient.

Voided urine is routinely collected from renal transplant patients to screen for polyomavirus. In rare cases, atypical lymphoid cells can be detected in voided urine and raise the suspicion of post-transplant lymphoproliferative disorder (PTLD). However, further immunohistochemistry of the cell block and flow cytometry is frequently limited by the low cellularity and poor preservation of voided urine. Therefore, PTLD of the renal allograft is usually diagnosed from tissue biopsy or nephrectomy specimens. Herein, we report a rare case of atypical cells in a voided urine cytology specimen from a kidney transplant recipient. Needle core biopsy of the renal allograft showed monomorphic PTLD. Diagn. Cytopathol. 2017;45:69-72. © 2016 Wiley Periodicals, Inc.

Transplantation-associated thrombotic microangiopathy isolated to a congenital anomaly of the lung.

TA-TMA is a post-hematopoietic stem cell transplant complication with clinical features of hemolytic anemia and thrombocytopenia. A 26-month-old child who had had an allogeneic transplant for treatment of DBA developed severe TA-TMA with heavy red blood cell and platelet transfusion dependence. Incidentally, he was found to have a lung sequestration. TA-TMA resolved and transfusion dependence resolved after resection of the sequestration. The finding suggests the malformation vasculature was selectively vulnerable to the trigger of TA-TMA-raising perhaps a clue to basic pathophysiology of TA-TMA and/or vascular malformations.