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Dermatopathic lymphadenopathy (DL) is a distinctive type of lymph node hyperplasia that typically occurs in the setting of chronic dermatologic diseases. DL generally self-resolves following disappearance of the underlying skin stimulus and does not require any specific therapy. We recently observed multiple myeloma oncogene 1/interferon regulatory factor 4 (MUM1/IRF4) expression in a case of DL using immunohistochemical methods. The goal of this study was to systematically assess DL cases for MUM1/IRF4 expression and to survey other histiocytic and Langerhans cell lesions. We particularly focused on Langerhans cell histiocytosis (LCH) because the differential diagnosis of DL versus LCH in lymph nodes can be challenging. We identified high expression of MUM1/IRF4 in all 22 cases of DL tested. Specifically, MUM1/IRF4+ dendritic cells comprised 50% to 90% (median, 80%) of all dendritic cells in the paracortex of dermatopathic lymph nodes, always showing moderate or strong intensity. Among 10 DL cases stained for MUM1/IRF4 and langerin/CD207 using dual immunohistochemistry, MUM1/IRF4+ and langerin+ Langerhans cells represented 5% to 60% (median, 30%) of paracortical dendritic cells. MUM1/IRF4 was also positive in reactive Langerhans cells in skin biopsy specimens of all cases of spongiotic dermatitis (n=10) and normal skin (n=15), and was negative in all cases of LCH (n=24), Rosai-Dorfman disease (n=10), follicular dendritic cell sarcoma (n=5) and histiocytic sarcoma (n=4). In aggregate, our findings support the utility of MUM1/IRF4 to highlight the dendritic cells of DL and to distinguish DL from other histiocytic and Langerhans cells lesions.

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) with unusual features, including some that can overlap morphologically with classic Hodgkin lymphoma (CHL), have been described. Herein, we describe 12 cases of NLPHL with fibrous bands and capsular fibrosis resembling, in part, nodular sclerosis (NS) CHL. Seven of 12 cases harbored Reed-Sternberg-like cells, further suggestive of CHL, but all cases lacked associated eosinophils and/or plasma cells in the background. In this cohort, all cases had areas of so-called pattern D (nodular T-cell rich) as a sole component in 7 (58%) cases or as a hybrid pattern along with pattern E (diffuse T-cell/histiocyte-rich) in 5 (42%) cases. The immunophenotype of the large neoplastic cells in these cases supported their being lymphocyte predominant cells of NLPHL, positive for CD20, CD79a, and OCT2, and negative for CD15 and CD30. However, PAX5 was weak in 9 of 11 cases similar to Hodgkin/Reed-Sternberg cells in CHL. We conclude that some cases of NLPHL are associated with fibrous bands and capsular fibrosis and resemble, in part, NS CHL. In our experience, NLPHL with NS-like features occurs in 10% to 15% of cases of NLPHL and is associated with a variant pattern (D and/or E). In addition, all patients in this cohort were not treated before biopsy, suggesting that the prominent sclerosis in these cases is inherent to disease biology. Recognition of NLPHL with NS-like features further expands the morphologic spectrum of NLPHL and helps avoid potential misdiagnosis as CHL.

Composite classic Hodgkin lymphoma and follicular lymphoma (CHLFL) is a rare and poorly characterized entity. Herein, we report the clinicopathologic features of 22 cases of CHLFL from 3 institutions and we assess 27 additional cases reported in the literature. In our cohort (n=22), patients with CHLFL had a median age of 61 years and an equal male to female incidence. Most cases (95%) arose de novo with the remaining patients having a history of non-Hodgkin lymphoma. CHLFL always involved lymph nodes (100%) and most cases (95%) revealed 2 distinct areas separately diagnostic for CHL and FL. The CHL component represented a variable proportion of the overall neoplasm (5% to 90%) and was either mixed cellularity (82%) or nodular sclerosis (18%) type. The Hodgkin/Reed-Sternberg cells expressed CD30 (100%), PAX5 (100%), CD15 (62%), BCL6 (47%), BCL2 (29%), and EBER (25%), in a polymorphous inflammatory background typical of CHL. The FL component was low-grade in 55%, grade 3A in 36%, and grade 3B in 9% of cases. All 3 cases investigated by cytogenetic methods for a clonal relationship between the CHL and FL components were clonally related. These clinicopathologic features of our cohort are similar to those of cases reported in the literature. The 5-year overall survival in combined patients with CHLFL (n=49) was 48%, comparable to CHL but worse than FL in the elderly. In summary, CHLFL is a rare entity that most often occurs in older adults, involves lymph nodes, and most commonly presents de novo. In the small number of cases assessed, the CHL and FL components are usually clonally related suggesting that the CHL and FL components may share a common progenitor B-cell, likely a mutated germinal center B-cell.

Reactive intralymphovascular immunoblastic proliferations (ILVIPs) may mimic aggressive lymphomas and are rarely reported. Herein, we characterize the clinicopathologic features of 8 patients with ILVIPs. No patients had lymphadenopathy, hepatosplenomegaly, or other findings suggestive of lymphoma. The ILVIPs involved the small or large intestine (n=5) and appendix (n=3). Patients were evaluated for abdominal pain, suspected appendicitis, intestinal obstruction, diverticulitis, volvulus, or tumor resection. Histologic sections showed expanded lymphovascular spaces filled by intermediate to large immunoblasts, positive for CD38, CD43, CD45, CD79a, and MUM1/IRF4 in all cases tested. Five of 6 (83%) cases were positive for CD30. CD20 was weakly positive in a subset of cells in 2 (25%) cases, and PAX5 was weakly positive in 4 (50%) cases. The immunoblasts expressed polytypic light chains in all cases tested. In 1 case, a subset of immunoblasts expressed T-cell markers indicating the presence of a T-cell component. The immunoblasts were negative for ALK, BCL-2, BCL-6, CD10, CD56, CD138, and Epstein-Barr virus-encoded small RNA in all cases assessed. The proliferation index shown by Ki-67 was high with a median of 80%. In all 6 cases tested, the immunoblasts were shown within lymphatic channels highlighted by D2-40. In conclusion, ILVIPs can be rarely observed in patients with inflammatory or infectious conditions, especially in gastrointestinal tract surgical specimens. The immunoblasts are predominantly of B-lineage with a postgerminal center immunophenotype and are located within lymphatic channels. It is essential to distinguish reactive ILVIPs from aggressive lymphomas to avoid unnecessary therapy.

Lymph nodes (LNs) involved by a myelodysplastic syndrome (MDS) are rare and uncommonly biopsied. In this study, we report 6 MDS patients who underwent an LN biopsy that showed MDS, and we summarize the clinicopathologic features of this cohort. All patients presented with lymphadenopathy (generalized in 5), 5 patients had splenomegaly, and 3 patients had hepatomegaly. Histologically, the LN architecture was distorted without complete effacement. MDS cells, mostly of the myeloid lineage, produced interfollicular expansion. These myeloid cells exhibited a spectrum of maturation, and immature and atypical forms were common, including eosinophils. Scattered megakaryocytes and nucleated erythroid cells were often present. Concurrent bone marrow aspirate and biopsy specimens in these patients showed persistent/resistant MDS. Following the diagnosis of LN involvement, patients did not respond well to therapy and all died by the time of the last follow-up, with a median survival of 6.7 months (range, 4.5 to 21.6 mo). In summary, patients with MDS uncommonly develop clinically evident lymphadenopathy prompting biopsy as a result of infiltration by MDS. MDS in LNs can be subtle, showing incomplete and sometimes mild distortion of the architecture, and ancillary studies including immunohistochemical and flow cytometric immunophenotypic analysis are often needed to establish the diagnosis. These data also suggest that the emergence of lymphadenopathy attributable to MDS is associated with poor treatment response and prognosis in MDS patients and that aggressive therapy or alternative treatment regimens need to be explored in this context.

The diagnosis of blastic plasmacytoid dendritic cell neoplasm (BPDCN) has been based on the expression status of multiple markers, including CD123. TCF4 was discovered recently to be an obligatory master regulator of plasmacytoid dendritic cells. We postulated that a tissue-based assay designed to detect dual CD123 and TCF4 expression would provide a highly reliable and practical marker for BPDCN in biopsy material. We designed, optimized, and validated a dual-color TCF4/CD123 immunohistochemistry stain for use in formalin-fixed paraffin-embedded tissue sections. The performance characteristics of the TCF4/CD123 stain were evaluated in 48 confirmed BPDCN cases. TCF4/CD123 coexpression was detected reproducibly in plasmacytoid dendritic cells. In BPDCN, the TCF4/CD123 stain showed coexpression in all (48/48; 100%) cases analyzed. Cases with concurrent samples from different anatomic sites showed comparable staining characteristics. In contrast, of 464 non-BPDCN cases comprising a wide range of hematolymphoid neoplasms and cutaneous lesions that might enter in the differential diagnosis of BPDCN, we identified dual expression of TCF4 and CD123 in only 1 case of B-lymphoblastic leukemia/lymphoma. On the basis of these findings, the TCF4/CD123 dual-color immunohistochemical stain had an analytic sensitivity of 100% and a specificity of 99.8%. Receiver operator characteristic analysis demonstrated an area under the curve of 1.000 (95% confidence interval: 0.999-1.000). In summary, the dual-color TCF4/CD123 immunohistochemistry stain provides a robust standalone and cost-effective assay for the diagnosis of BPDCN.

Mantle cell lymphoma (MCL) represents 4% to 9% of all non-Hodgkin lymphomas and is characterized by CD5 and cyclin D1 expression and t(11;14)(q13;q32). However, about 5% of MCL lack CD5 expression and is poorly characterized. Here, we present 58 patients with CD5 negative (CD5) MCL and compared them with a group of 212 typical CD5 positive (CD5) MCL cases. There were 39 men and 19 women with a median age of 66 years (range, 36 to 88). Compared with CD5 positive (CD5) MCL patients, patients with CD5 MCL showed a lower male-to-female ratio (P=0.006) and a higher frequency of "bone marrow non-nodal" presentation (P=0.01). All other clinicopathologic features, including the frequency of SOX11 expression, were similar between the 2 groups. Treated with similar regimens, patients with CD5 MCL showed a significantly longer progression-free survival (PFS) (P=0.01) and a tendency for longer overall survival (OS; P=0.078) than CD5 positive (CD5) MCL patients. Univariate analysis showed of the well-known poor prognostic factors, only Mantle Cell Lymphoma International Prognostic Index was an inferior prognostic factor and blastoid/pleomorphic morphology and high Ki67 were not associated with prognosis in CD5 MCL patients. Multivariate Cox regression analysis showed CD5 expression was an independent prognostic factor for PFS (P=0.031) but not OS in MCL patients. In conclusion, the results suggest that patients with CD5 MCL have a more favorable prognosis than CD5 MCL patients, although the clinicopathologic features of both groups are largely similar. CD5 MCL may represent a distinct variant of MCL and needs to be included in the differential diagnosis of CD5 small B-cell lymphomas.

Immunoglobulin (Ig)G4-related sclerosing disease is a fibroinflammatory disorder characterized by tumor-forming lesions at multiple anatomic sites and by increased serum levels of IgG4. IgG4-related lymphadenopathy, defined as lymphadenopathy developing in patients with IgG4-related sclerosing disease, is known to manifest in 5 histologic patterns: (1) multicentric Castleman disease-like; (2) reactive follicular hyperplasia; (3) interfollicular plasmacytosis with immunoblasts; (4) progressive transformation of germinal centers-like; and (5) inflammatory pseudotumor-like. Herein, we describe a 37-year-old man with an additional pattern of IgG4-related lymphadenopathy that we designate as infectious mononucleosis-like. This pattern is characterized by effacement of the nodal architecture by an infiltrate composed of numerous mature plasma cells, plasmacytoid cells, large basophilic transformed lymphocytes (immunoblasts), and small-sized to medium-sized lymphocytes and histiocytes. Perivascular fibrosis and karyorrhectic debris with fibrin deposition were also focally identified. Epstein-Barr virus-encoded small RNA in situ hybridization showed scattered positive small lymphocytes, 1% to 2%. The initial spike of IgG4 in serum (>4400 mg/dL) decreased by half after 1 month of steroid therapy. His condition was stable during 1 year of follow-up. We report this case because the findings expand the morphologic spectrum of IgG4-related lymphadenopathy.

Isocitrate dehydrogenase 1 (IDH1) and IDH2 mutations occur in a variety of myeloid neoplasms. Immunohistochemistry (IHC)-based direct visualization of mutant clones of hematopoietic cells can be useful for rapid diagnostic screening and for monitoring treatment response. In this study, we first evaluated the sensitivity and specificity of the IDH1 p.R132H mutation-specific antibody by IHC. All IDH1 wild type cases (n=11) and IDH1 mutant cases with a non-p.R132H mutation (n=30) were negative by IHC, demonstrating 100% antibody specificity. All the initial diagnostic specimens with IDH1 p.R132H mutation including acute myeloid leukemia (n=30), myelodysplastic syndromes (MDS) (n=10), MDS/myeloproliferative neoplasms (MPN) (n=4), and MPN (n=5) were positive by IHC, demonstrating 100% antibody sensitivity. Both immature and mature myeloid cells showed immunoreactivity. Erythroid precursors, lymphoid cells, endothelial cells, and osteoblasts were consistently negative by IHC. We then evaluated the follow-up specimens with a known IDH1 mutation status including acute myeloid leukemia (n=23), MDS (n=2), MDS/MPN (n=2), and MPN (n=2). Thirty-three IDH1 p.R132H mutant cases were positive by IHC and 12 IDH1 mutation negative cases were negative by IHC. However, IHC reactivity in up to 25% of bone marrow cells was noted in 8 of 20 polymerase chain reaction-negative cases, all from patients with a known history of IDH1 p.R132H mutation indicating sampling error or a sensitivity issue with molecular tests. These data indicate that IHC is a highly specific and sensitive tool to detect IDH1 p.R132H mutation in bone marrow involved by myeloid neoplasms. In addition, IDH1 p.R132H IHC also allows localization and assessment of the maturation stage of the clones carrying the mutation.

A subset of patients with chronic myelomonocytic leukemia (CMML) presents with significance myelofibrosis. In myelodysplastic syndromes, significant myelofibrosis has been associated with adverse outcomes and p53 dysregulation. However, in CMML the clinical and molecular correlates of significant myelofibrosis at presentation remain poorly understood. From a cohort of 651 CMML patients, we identified retrospectively 20 (3.1%) cases with moderate to severe reticulin fibrosis (CMML-F) detected at diagnosis, and we compared them to CMML patients without fibrosis (n=631) seen during the same period. Patients with CMML-F had a median age of 69.8 years (range, 24.8 to 91.2 y) and most (13; 65%) were men. Patients with CMML-F differed significantly from other CMML patients across the following parameters: white blood count, absolute monocyte count, serum lactate dehydrogenase level, splenomegaly, and bone marrow blast percentage. Notably, the frequency of JAK2 p.V617F mutation was higher in CMML-F patients compared with other CMML patients (P

Primary bone (PB) diffuse large B-cell lymphoma (DLBCL) is rare and has a favorable prognosis, but the underlying biological mechanisms remain unknown. In this study we analyzed the clinicopathologic features of 160 patients with PB-DLBCL in comparison with 499 nonosseous DLBCL. Compared with patients with nonosseous DLBCL and secondary involvement of bone by DLBCL, PB-DLBCL patients less frequently had elderly age, B-symptoms, elevated serum lactate dehydrogenase levels, and high International Prognostic Index at diagnosis, more frequently had germinal center (GC) subtype (approximately 90%) and complete remission, and had significantly better survival. The 5-year progression-free and overall survival rates of PB-DLBCL patients were 80% and 93%, respectively, superior to both GC B-cell-like (GCB) and activated B cell-like subtypes of DLBCL. Further stratifying nonosseous DLBCL cell-of-origin subtypes by clinical factors showed that PB-DLBCL had similar survival rates as the centrocyte-origin (CC) subtype of DLBCL-GCB classified by the B-cell-associated gene signature algorithm. To better understand the favorable outcome of PB-DLBCL patients, gene expression profiling and microRNA profiling were performed in a small subset of PB-DLBCL. The gene expression profiles of PB-DLBCL resembled those of nonosseous DLBCL-GCB-CC, but were distinct from other DLBCL cell-of-origin especially the centroblast-origin (CB) subtype. Compared with DLBCL-GCB-CB, PB-DLBCL and DLBCL-GCB-CC also had much higher levels of miR-125a-3p, miR-34-3p, and miR-155-5p, and significantly lower levels of miR-17-5p and miR-17-3p. These results demonstrated that PB-DLBCL is clinically distinct, and the cell-of-origin of PB-DLBCL stems from centrocytes in the GC, that are biologically attributed for the favorable prognosis of PB-DLBCL.

Primary cutaneous gammadelta T-cell lymphoma (PCGD TCL), an aggressive type of lymphoma, accounts for approximately 1% of all primary cutaneous lymphomas. We have occasionally observed changes in T-cell antigen expression (immunophenotypic [IP] shift) over time, a phenomenon that is considered rare in T-cell lymphoma including cutaneous T-cell lymphoma. Therefore, we assessed sequential biopsies of PCGD TCL for possible IP shifts of the lymphoma cells. We searched for cases of PCGD TCL with consecutive biopsies to perform a comprehensive immunohistochemical analysis of paired specimens. A median of 12 markers per case was tested. We evaluated the percentage of neoplastic lymphocytes and determined the differential expression of antigens (gain, loss, increase or decrease). We identified 9 patients with PCGD TCL with consecutive biopsies. All (100%) cases had IP shifts of at least 1 antigen, whereas overall 22 pairs of markers were shifted: gain of reactivity occurred in 7 (31.8%) and loss in 3 (13.6%); increased reactivity in 4 (18.2%) and decreased in 8 (36.4%). Molecular analysis of TCRgamma showed identically sized monoclonal rearrangements between biopsy pairs in 4/4 (100%) patients. There was no correlation between IP shifts and the clinical appearance of lesions, histopathologic or cytologic features, or molecular rearrangements. IP shifts are common in PCGD TCL, occurring in all patients in this study and involving a variety of antigens. IP shifts do not seem to be linked to changes in the T-cell clone and are without obvious clinical or morphologic correlates. The occurrence of IP shifts in PCGD TCL suggests that antigen modulation may be involved in pathogenesis. IP shifts are somewhat frequent in T-cell lymphoma; however, it does not suggest a second neoplasm, and molecular studies can be used to determine clonal identity.

Primary cutaneous gamma-delta (γδ) T-cell lymphoma is a rare disease that typically involves the dermis and subcutis. Cases of primary cutaneous T-cell lymphomas showing γδ phenotype and predominantly epidermotropic pattern (EγδTCL) are not well defined. In this series, cases of primary cutaneous T-cell lymphomas showing γδ phenotype were reviewed and classified as predominantly epidermotropic (EγδTCL) when >75% of lymphoma cells resided in the epidermis or predominantly dermal and/or subcutaneous (DSγδTCL). Clinical, pathologic, and immunophenotypic features were compared in 27 biopsies from 13 patients of EγδTCL and 13 biopsies from 7 patients of DSγδTCL. The lymphoma cells were diffusely positive for CD3 and T-cell receptor (TCR)γ, mostly positive for granzyme B and TIA-1, variably positive for CD8, CD7, and CD30, and negative for CD4 and TCRβ. Two patients with EγδTCL had dissemination to lymph nodes and 1 to the lung; 1 patient with DSγδTCL had gastrointestinal involvement. The median survival of patients with EγδTCL was not reached, and with a median follow-up of 19.2 months, 3/13 died. In contrast, the median survival of patients with DSγδTCL was 10 months, and after a median follow-up of 15.6 months, 5/5 died (P

MYC rearrangement in mantle cell lymphoma (MCL) is rare, and its clinicopathologic significance is not well defined. We report 17 cases of MCL with 8q24/MYC rearrangement, detected at the time of initial diagnosis of MCL in 10 patients and subsequently during the clinical course in 7 patients. There were 12 men and 5 women with a median age of 61 years (range, 49 to 81 y). Fourteen patients had lymphadenopathy (Ann Arbor stage III/IV), and 3 patients presented with a leukemic pattern without lymphadenopathy. Thirteen of 14 patients with available karyotyping data had a complex karyotype. In 8 cases the partner chromosome locus was an IG locus: t(8;14) (n=7) and t(8;22) (n=1). When MYC rearrangement was detected, most patients had a high-risk MCL international prognostic index, and the lymphoma cells had histologically aggressive features. Immunophenotypic analysis showed that the lymphoma cells were positive for cyclin D1 (n=16/16), Myc (9/11), and P53 (n=9/9). The Ki-67 proliferation rate was high (≥60%) in 10/11 cases. All patients received chemotherapy. The median follow-up time was 23 months. Clinical follow-up was available for 14 patients and treatment response in 13 patients. Eleven of 13 patients had refractory or relapsed disease, and 11 patients died. In conclusion, MCL with MYC rearrangement is characterized by advanced-stage disease, aggressive morphologic features, a high proliferation rate, p53 expression, a complex karyotype, and a poor prognosis. We believe these neoplasms fit within the overall concept of double-hit lymphoma, and the designation double-hit MCL may be helpful. We also believe that MYC rearrangement in MCL conveys important prognostic information that should be incorporated into the pathology report.

Hepatosplenic T-cell lymphoma (HSTCL) is a rare, aggressive T-cell lymphoma that can be challenging to diagnose. In particular, distinguishing HSTCL from T-cell large granular lymphocytic (T-LGL) leukemia of γδ T-cell receptor (TCR) type is difficult without examination of a splenectomy specimen. In this study, we systematically assessed a series of HSTCL cases for findings reported in the literature as supporting or not supporting the diagnosis of HSTCL. We also compared HSTCL with a group of cases of T-LGL of γδ TCR type. Criteria assessed in this study included: B-symptoms, massive splenomegaly, lymphadenopathy, extranodal involvement, peripheral lymphocytosis, lymphoma cells that expand bone marrow sinuses, lymphocyte azurophilic granules, immunophenotype, evidence of infection by Epstein-Barr virus, human immunodeficiency virus, or human T-cell leukemia virus type 1, isochromosome 7q, trisomy 8, and TCR gene rearrangement status. On the basis of the data of this study, we conclude that massive splenomegaly, bone marrow sinusoidal expansion by lymphoma cells, and lymphocytes devoid of azurophilic granules were significantly more common in HSTCL patients than in γδ T-LGL patients (P

Hepatosplenic T-cell lymphoma (HSTCL) is a rare type of lymphoma. Patients have a poor prognosis, and there is no standard of care. We evaluated 28 HSTCL patients to determine factors that may be associated with outcome. There were 19 men and 9 women with a median age of 32.5 years. Most patients had massive splenomegaly, and bone marrow showed sinusoidal involvement by lymphoma. The HSTCL cells expressed γδ T-cell receptor (TCR) in 20 (74%), αβ TCR in 5 (19%), and neither in 2 (7%) patients (1 case not assessed). Conventional cytogenetics and/or fluorescence in situ hybridization analysis in 24 patients at diagnosis showed isochromosome 7q (i7q) in 10 (42%) and trisomy 8 in 8 (33%) patients. Median overall survival (OS) and event-free survival (EFS) were each 28.3 months. Serum bilirubin level ≥1.5 mg/dL, αβ TCR expression, and trisomy 8 each correlated significantly with shorter OS and EFS. Patients with HSTCL received a variety of chemotherapy regimens with no regimen better than any other. However, patients who underwent stem cell transplant showed longer survival (OS: hazard ratio 0.3, P=0.09; EFS: hazard ratio 0.2, P=0.034). In conclusion, although HSTCL patients have a poor prognosis overall, the data presented support the novel suggestions that HSTCL patients can be stratified into 2 prognostic groups, with an elevated serum bilirubin level, αβ TCR expression, and trisomy 8 identifying a poorer prognostic group. In addition, the outcomes of this patient cohort suggest that stem cell transplantation has value for the treatment of patients with HSTCL.

Patients with MYC/BCL2 double-hit lymphoma (DHL) are known to have an aggressive clinical course and to respond poorly to various therapies including intensive chemotherapy and stem cell transplant. Less is known about high-grade B-cell lymphoma with MYC rearrangement without concomitant BCL2 and BCL6 rearrangement, designated here as single-hit lymphoma (SHL). In this study, we assessed 61 cases of SHL and compared them with 83 cases of DHL, all confirmed by MYC, BCL2, and BCL6 fluorescence in situ hybridization studies. Although many clinicopathologic features overlap between patients with SHL and those with DHL, distinct features were observed in SHL. Patients with SHL had tumors with a higher prevalence of p53 overexpression (P=0.047), less frequent expression of CD10, BCL2, and BCL6 (P

The growth of angioimmunoblastic T-cell lymphoma (AIL) in lymph node often produces complex patterns of neoplastic T cells and nonneoplastic B cells that complicate diagnosis. To understand better how these different patterns of B-cell expansion arise, we compared the microanatomic localization of B cells and T cells within the follicular, paracortical, and sinusoidal compartments in 30 patients with AIL (including 10 with multiple sequential samples) with that seen in 33 cases of other types of T-cell lymphoma. With early or partial nodal involvement in AIL, germinal center B-cell expansions were relatively undisturbed and often associated with a variably distended D2-40+ CD31+ perifollicular sinus that surrounded most of the follicular compartment. Identifiable tumor T cells resided mostly in the paracortex. In later stages of AIL with more complete nodal effacement, bcl-6+ follicular B-cell proliferations shifted to distorted FDC networks arrayed along patent trabecular sinuses and were more intermixed with tumor T cells. In both AIL and other T-cell lymphomas, the density and locations of follicular B cells as well as bcl-6-negative monocytoid B cells were largely related to the patency of adjacent sinuses, except in Epstein-Barr virus (EBV)+ and histiocyte-rich B-cell proliferations, which arose in paracortical locations. The prominence of the perifollicular sinus in early stages of AIL resembled that seen in reactive lymphadenitis during conditions of lymphatic engorgement and implicates cytokines within lymph fluid in maintaining both the normal and altered germinal center reactions. Patterns of sinus drainage largely explain the useful changes in B-cell distribution that occur in nodal T-cell lymphomas and represent an important tool in classification and diagnosis of these tumors.

The spectrum of bone marrow lesions in patients with nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) has not been evaluated systematically. In this study, we analyzed a cohort of 262 NLPHL patients who underwent staging bone marrow evaluation or targeted bone biopsy as a part of their initial diagnostic workup, among which lymphoma was detected in 24 (9.2%) patients. Eleven patients had bone marrow findings of NLPHL (few large B cells in a background of small B cell and T cell), and 13 patients had either T-cell/histiocyte-rich large B-cell lymphoma (large B cells in a background of T cells and histiocytes) or typical diffuse large B-cell lymphoma (sheets of large B cells). Bone marrow involvement was more common in patients with variant NLPHL histologic patterns in the lymph node as compared with those who had classic patterns (12/18 vs. 4/16; P=0.02). An additional 27 NLPHL patients had bone marrow specimens involved by lymphoid aggregates composed of small T cells and B cells without large B cells; this subgroup had a longer event-free survival than patients with lymphoma in the bone marrow (145 vs. 35 mo). Disease recurrence or progression was more frequent in patients with bone marrow involvement by either NLPHL or LBCL, compared with patients who had lymphoid aggregates (13/21 vs. 8/26; P=0.04). In conclusion, staging bone marrow sampling detects lymphoma in a sizeable subset of NLPHL patients, particularly those with variant histologic patterns. Lymphoid aggregates lacking large B cells in staging bone marrow specimens from NLPHL patients can be regarded as clinically benign without impact on stage, outcome, or risk stratification.

Waldenstrom macroglobulinemia (WM) is a clinicopathologic syndrome in which a B-cell neoplasm involving the bone marrow, usually lymphoplasmacytic lymphoma (LPL), is associated with immunoglobulin M paraprotein in the serum. Extramedullary involvement occurs in a subset of patients and is infrequently examined histologically. The files of M.D. Anderson Cancer Center were searched for patients with WM who underwent biopsy of one or more extramedullary sites during the course of disease. Each biopsy specimen was classified using the criteria of the World Health Organization classification. The study group consisted of 44 patients (26 men and 18 women), with a total of 51 specimens obtained from lymph nodes (n = 36), soft tissue (n = 4), spleen (n = 3), skin (n = 2), lung (n = 2), tonsils (n = 1), colon (n = 1), liver (n = 1), and gallbladder (n = 1). Lymphoplasmacytic lymphoma was the most common histologic type, in 40 (78%) samples. This category was morphologically heterogeneous and was further subclassified as lymphoplasmacytic (n = 21), lymphoplasmacytoid (n = 18), and polymorphous (n = 1). Four of these LPL cases morphologically resembled marginal zone B-cell lymphoma. Four additional samples were involved by diffuse large B-cell lymphoma, probably transformed from LPL. Three more samples were involved by LPL with unusual features: two were CD5-positive and one was a composite tumor with classical Hodgkin's disease. Other categories of lymphoma in this group of patients with WM included small lymphocytic lymphoma/chronic lymphocytic leukemia (n = 2), mantle cell lymphoma (n = 1), and follicular lymphoma (n = 1). Waldenstrom macroglobulinemia is most commonly associated with LPL but can rarely occur with other types of B-cell lymphoma. Lymphoplasmacytic lymphoma in patients with WM is morphologically heterogeneous and can be indistinguishable from marginal zone B-cell lymphoma. CD5+ B-cell lymphomas with features otherwise typical of LPL are rare, and we think these tumors are part of the spectrum of LPL.

BCL-2 is an antiapoptotic protein overexpressed in follicular lymphomas, principally as a result of the t(14;18)(q32;q21), and useful in distinguishing follicular lymphoma (usually BCL-2 positive) from follicular hyperplasia (BCL-2 negative). BCL-2 is also overexpressed in other lymphoma types without the t(14;18), including marginal zone B-cell lymphoma, because of other, poorly understood mechanisms. It has been suggested that BCL-2 immunoreactivity can distinguish between malignant (BCL-2 positive) and reactive (BCL-2 negative) marginal zone B cells. In this study, we evaluated 26 spleen, 10 abdominal lymph node, and 3 ileum specimens with marginal zone B-cell hyperplasia for BCL-2 expression immunohistochemically. We also analyzed these cases using polymerase chain reaction methods to evaluate for the presence of clonal rearrangements of the immunoglobulin heavy chain gene (IgH) using consensus V FRIII and J region primers, and the t(14;18) involving both the major breakpoint and the minor cluster regions of the bcl-2 gene. All (100%) cases of splenic, abdominal lymph node, and ileal marginal zone hyperplasia displayed strong BCL-2 reactivity in the marginal zone B cells. In all cases analyzed, IgH polymerase chain reaction demonstrated a polyclonal pattern, and bcl-2/JH DNA fusion sequences were not detected. Our results indicate that BCL-2 is consistently expressed by reactive marginal zone B cells of the spleen, abdominal lymph nodes, and ileal lymphoid tissue and should not be used as a criterion for discriminating between benign and malignant marginal zone B-cell proliferations involving these sites.

The plasma cell variant of Castleman's disease (PCD) may occur in a variety of clinical settings. One recently delineated type of PCD is caused by human herpesvirus 8 (HHV8) infection. Lymph nodes from 25 patients with PCD, including six HHV8+ and 19 HHV8- cases, were studied. Three patients with HHV8+ PCD were also infected with human immunodeficiency virus-1. Features common to all cases were interfollicular plasmacytosis and variably hyperplastic and regressed follicle germinal centers. Features associated only with HHV8+ PCD included follicle dissolution resulting from blurring of the mantle zone boundary (p = 0.0001), presence of atypical plasma cells and immunoblasts within these areas (p = 0.0006), and more prominent interfollicular vascular proliferation than in HHV8- PCD. HHV8+ cells were predominantly immunoblasts and small lymphocytes that were highly enriched in the mantle zones of altered follicles. These areas showed a predominance of plasmacytoid forms expressing lambda light chain in four of six cases. The extrafollicular fibroblastic network surrounding altered germinal centers demonstrated marked upregulation of low-affinity nerve growth factor receptor in five of five HHV8+ cases but in only two of 10 HHV8- cases. We conclude that HHV8+ PCD is distinctive histologically because of the accumulation of infected lymphocytes in the mantle zone leading to progressive dissolution of the germinal center and altered regulation of the surrounding stroma.

Extranodal NK/T-cell lymphoma, nasal type (ENKTL) is uncommon in the United States. We report 73 patients with ENKTL, including 49 men and 24 women (median age, 46 y). Sixty-three patients had nasal/upper aerodigestive tract disease; 10 had extranasal disease involving skin, small intestine, epiglottis, testis, adrenal glands, kidney, and breast. Complete staging data were available for 68 patients: 44 stage I/II and 24 stage IV. Fifteen of 69 (22%) had lymphadenopathy and 10/63 had bone marrow involvement. Histologically, 67/73 (92%) showed necrosis, and 48/70 (69%) had an angiocentric/angiodestructive growth pattern. The neoplastic cells showed a wide spectrum: medium sized (n=34), mixed small and large (n=21), large (n=13), and small (n=5). In situ hybridization for Epstein-Barr virus-encoded small RNA was positive in every case. Immunohistochemical studies showed expression of cytotoxic markers (100%), T-bet (96%), CD2 (96%), CD3 (93%), CD56 (90%), and ETS-1 (64%). Ki-67 was ≥60% in 46% cases. Therapy was known for 64 patients; 14 received only chemotherapy, 8 radiation alone, and 42 received combined radiation and chemotherapy. Median survival was 4.2 years, and 5-year overall survival was 46% (median follow-up, 3.8 y). Extranasal disease, high International Prognostic Index score, and high proliferation rate correlated with poorer prognosis. We conclude that ENKTL cases in the United States are similar to those reported in Asia and other countries. Absence of the angiocentric/angiodestructive pattern and presence of lymphadenopathy, features underemphasized in the literature, occurred in appreciable subsets of patients. The International Prognostic Index score, anatomic site of disease, and proliferation rate had prognostic value in this patient cohort.

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) has clinicopathologic, immunophenotypic, and molecular features that are distinct from classical Hodgkin lymphoma (cHL). Distinguishing these entities is usually straightforward, but unusual variants of NLPHL have been described that can be problematic diagnostically and potentially have clinical significance. We describe a case of NLPHL showing a variant histologic pattern characterized by small and large clusters of lymphocyte predominance cells within nodules defined by follicular dendritic cell meshworks, associated with numerous neutrophils and areas of internodular fibrosis. Focally, the neoplastic cells had lacunar cell-like cytologic features. The resulting combination, not previously reported, closely mimicked the syncytial variant of nodular sclerosis cHL. After chemotherapy the patient was free of disease 14 years later. In our review of the literature we identified rare cases of NLPHL that had similar histologic features, but lacked the neutrophilic infiltration. Recognition of this rare variant, facilitated by immunohistochemical studies in this case, further expands the morphologic spectrum of NLPHL.

Lymphomas involving the breast account for approximately 2% of extranodal and

The 8p11 myeloproliferative syndrome (EMS) is a rare hematologic malignancy characterized by myeloid hyperplasia, eosinophilia, and precursor lymphoblastic lymphoma, associated with balanced translocations involving chromosome 8p11, most commonly t(8;13)(p11;q12). Approximately 75% of EMS patients present with or develop precursor T-cell lymphoblastic lymphoma, and most subsequently develop acute myeloid leukemia. Here we describe the morphologic and immunophenotypic features of 6 cases of t(8;13)-positive bilineal lymphoma of mixed T-cell and myeloid lineage, 5 in lymph nodes and 1 in breast. The patients, 3 males and 3 females, ranged in age from 6 to 19 years. Histologically, each tumor was composed of 2 distinct cellular components: small to medium-sized T cells with scant cytoplasm that resembled lymphoblasts, and larger immature-appearing cells with more abundant eosinophilic cytoplasm that resembled myeloblasts, a subset of which expressed myeloid antigens. In all cases, the latter component tended to surround residual lymphoid follicles and/or blood vessels. Numerous eosinophils and prominent high endothelial venules were present in all of the lymph node specimens. Interestingly, cells of both components expressed CD3 on immunohistochemical stains. In conclusion, EMS associated with t(8;13) should be suspected in patients with a bilineal tumor that involves lymph nodes or other extramedullary sites. We believe that these bilineal neoplasms of mixed T-cell and myeloid lineages, which present as lymphoma, are analogous to bilineal leukemias. They likely arise from an early hematopoietic cell with potential to differentiate along T-cell and myeloid pathways.

Cellular Jun (c-Jun), a member of the JUN family, is an activator protein-1 transcription factor involved in cell differentiation, proliferation, and apoptosis that can be activated by phosphorylation at serine-73 and -63 residues. Using tissue microarrays and immunohistochemistry, we investigated c-Jun expression and serine-73 phosphorylation in 112 CD30 lymphomas and 232 CD30 lymphomas of B- or T-cell lineage, and 24 cases of lymphomatoid papulosis. c-Jun was expressed exclusively by CD30 lymphoproliferative disorders including 41/41 (100%) classical Hodgkin lymphoma (cHL), 20/23 (87%) anaplastic lymphoma kinase (ALK)+ anaplastic large cell lymphoma (ALCL), 18/26 (69%) ALK- ALCL, 5/9 (56%) primary cutaneous ALCL, 4/11 (36%) CD30 diffuse large B-cell lymphoma (DLBCL), and 11/24 (46%) cases of lymphomatoid papulosis. The percentage of c-Jun-positive tumor cells was highest in cHL and ALCL (P=0.002). In contrast, all CD30 lymphomas, including nodular lymphocyte predominant HL and CD30 non-Hodgkin lymphomas of B- or T-cell lineage were negative for c-Jun. Serine-73 phosphorylated c-Jun (p-c-Jun), the activated form of c-Jun, was expressed more frequently and at a higher level in cHL and ALK+ ALCL than other CD30 tumors. The percentage of p-c-Jun-positive tumor cells correlated significantly with the percentage of total c-Jun-positive cells (P

The inv(16)(p13q22) or, less commonly the t(16;16)(p13;q22), is characteristic of acute myeloid leukemia (AML) with abnormal bone marrow eosinophils, also known as AML-M4Eo. This abnormality creates a fusion gene, 5' core binding factor beta (CBF-beta) gene and the 3' MYH11 gene, the latter encoding smooth muscle myosin heavy chain gene (SMMHC). Detection of this abnormality is important for diagnosis and is most commonly done by cytogenetics or molecular methods. In this study, we determined the utility of immunohistochemical and immunofluorescence methods using a rabbit polyclonal antibody (AH107) against the C-terminus of the CBFbeta-SMMHC chimeric protein for diagnosis of AML-M4Eo. Thirty-nine AML-M4Eo cases and 55 cases of other types of AML were evaluated. Immunohistochemical analysis of routinely processed paraffin-embedded bone marrow sections showed that CBFbeta-SMMHC staining is predominantly nuclear in all cases of AML-M4Eo and is not nuclear in other AML types. Four cases of AML-M4Eo double-stained for CBFbeta-SMMHC and CD34 showed the fusion protein in CD34-positive blasts. Indirect immunofluorescence analysis of fresh bone marrow aspirate smears showed that AML-M4Eo blasts have a distinct nuclear microgranular or fine-speckled pattern of staining, with or without faint cytoplasmic staining. By contrast, other types of AML and normal bone marrow specimens were either negative or had a nonspecific pattern of staining. In summary, immunostaining for CBFbeta-SMMHC using either immunohistochemical or immunofluorescense analysis as described here reveals a distinctive pattern of staining for AML-M4Eo. This approach is a specific, reliable, and convenient alternative to cytogenetic and molecular methods for the diagnosis of AML-M4Eo and may be particularly helpful in cases with indeterminate histologic features or in cases in which cytogenetic and molecular studies are either uninformative or not available.

We describe five cases of mantle cell lymphoma involving skin. Three patients initially presented with skin lesions but had evidence of widespread disease at time of diagnosis or with relatively short follow-up. One patient was known to have disseminated disease before he developed skin lesions. One patient presented with a solitary skin nodule on the thigh and has developed multiple smaller nodules on the same leg, but no other sites of disease over 30 months of clinical follow-up. This case fulfills the criteria for primary cutaneous lymphoma as proposed by the European Organization for Research and Treatment of Cancer. Biopsy of the skin lesions in all cases showed predominantly dermal and focally subcutaneous lymphoid infiltrates, preferentially perivascular and periadnexal in four cases, and nodular in one case. The tumors were composed of small- to medium-sized lymphocytes with irregular nuclear contours. Four cases had blastoid and one case had typical cytologic features. Immunophenotypic studies showed that all cases were positive for CD20 and cyclin D1, and four of five were positive for CD5. Four cases, including the CD5-negative case, had evidence of the t(11;14) shown by either fluorescence in situ hybridization methods performed on skin tumors or conventional cytogenetic analysis performed on involved bone marrow. We conclude that mantle cell lymphoma can involve skin, usually as a manifestation of disseminated disease, and is often associated with blastoid cytologic features. Rare cases of mantle cell lymphoma may arise in skin.

We describe five patients with treated low-grade B-cell neoplasms who subsequently developed Epstein-Barr virus (EBV)-positive B-cell lymphoproliferative disorders (BLPDs). The low-grade B-cell neoplasms were B-cell chronic lymphocytic leukemia in four patients and splenic marginal zone lymphoma in one patient. All patients had received treatment with fludarabine for the low-grade B-cell neoplasm, and three had also received Campath-1H. The EBV-BLPDs arose 2-12 months after completion of fludarabine therapy and morphologically resembled the EBV-BLPDs that occur in the setting of iatrogenic immunodeficiency. Molecular genetic studies showed that these lesions were clonally distinct from the low-grade B-cell neoplasm in three of four cases assessed. Two patients did not receive therapy for the EBV-BLPD. The lesions regressed spontaneously in both patients but recurred in one. One patient underwent surgical excision and remains without evidence of the EBV-BLPD. One patient received aggressive multiagent chemotherapy with a complete response initially, but the EBV-BLPD recurred after 12 months. One patient received antiviral therapy and responded completely but died 2 months later of an opportunistic infection. We conclude that patients with low-grade B-cell neoplasms treated with fludarabine, possibly in combination with other immune suppressive agents, may subsequently develop EBV-BLPDs that morphologically resemble other iatrogenic immunodeficiency-associated BLPDs. Most are clonally distinct from the underlying low-grade B-cell neoplasm. A subset of these lesions may regress without systemic therapy.

We report 15 patients with CD4-CD8-"double-negative" T-cell lymphoma arising in skin. There were seven women and eight men with a mean age at diagnosis of 53 years (range 19-77 years). All but two patients presented with solitary or multiple cutaneous nodule(s). Initial and recurrent biopsy specimens showed a dense infiltrate centered in the mid-dermis (extending into subcutis when sampled) of small to intermediate-sized lymphocytes with indistinct nucleoli and frequently irregular nuclear contours. Periadnexal infiltration and epidermal ulceration were present in five cases with the intraepidermal cells being primarily reactive CD4+ T cells. All cases were negative for CD30 and terminal deoxynucleotidyltransferase; one showed expression of CD56, and six of eight tested cases were positive for T-cell receptor-delta expression. Despite systemic chemotherapy, all 12 patients with clinical follow-up showed recurrent or progressive disease with widespread cutaneous dissemination in 10 of 12. Eventual dissemination to lymph nodes or bone marrow occurred in two patients each, with at least nine patients dead of disease or treatment complications. Only two patients achieved lasting clinical remission (with 2'-deoxycoformycin/pentostatin and nelarabine, respectively). CD4-CD8-"double-negative" CTCL has distinctive histologic features and cytomorphology with a marked propensity for rapid multifocal cutaneous dissemination.

To determine whether the mononuclear cells (MC) and multinucleated giant cells (GC) of giant cell tumor of tendon sheath (GCTTS) exhibit evidence of monocyte/macrophage lineage, we studied their antigenic features (seven cases, paraffin sections; two cases, frozen sections) and enzymatic features in situ (four cases, plastic sections). Both MC and GC expressed a monocyte/macrophage phenotype: HLA-A, B, C+, HLA-DR+, T200+ (Leukocyte common antigen), Leu-M3+ and Leu-3+. MC and GC also expressed similar enzymatic phenotypes which resembled that of osteoclasts. Both were rich in acid phosphatase and contained smaller, variable amounts of ATPase, beta-glucuronidase, alpha-naphthyl acetate esterase, and 5'-nucleotidase. Both lacked alkaline phosphatase. Reactive osteoclasts in plastic and paraffin sections were also T200+, a finding strongly supporting their bone marrow derivation and leukocytic differentiation. In plastic sections, osteoclasts were additionally reactive with macrophage antigen EBM11. In aggregate, these data suggest that GCTTS is a true histiocytic lesion of monocyte/macrophage lineage composed of phenotypically similar MC and GC that most closely resemble osteoclasts. We found no evidence that GCTTS cells resemble osteoblasts, fibroblasts, or synovial sarcoma cells. Furthermore, expression of the Ki-67 nuclear antigen by 1–2% of MC but not by GC suggests that the proliferating cells in GCTTS are restricted to its MC component.