Immunohistochemical typing of non-Hodgkin's lymphoma-comparing working formulation and WHO classification

The recent WHO classification of non-Hodgkin's lymphoma is based on the morphology and immunohistochemical expression of the lymphoma cells and to a lesser extent, on the molecular and cytogenetic findings. Fifty-three cases of non-Hodgkin's lymphoma were included in the study. Of these, seven cases were primary extra nodal lymphomas. Twenty two patients had peripheral blood and/or bone marrow involvement. A detailed morphological assessment was done and classified using the International working formulation. The two most common types encountered were diffuse large cell lymphoma and small lymphocytic lymphoma. Immunohistochemistry was done using labeled streptavidin-biotin peroxidase complex with CD3, CD20, CD15, CD30, CD 45 (leukocyte common antigen), Cyclin D1, EMA (epithelial membrane antigen). 38 cases (72%) showed B cell expression and 12 cases (22.5%) showed T cell expression. Three cases did not express either marker. B-cell diffuse large cell lymphoma (26%) was found to be the predominant B cell non-Hodgkin's lymphoma. The commonest T-cell lymphoma was T lymphoblastic lymphoma (67%) followed by peripheral T cell angioimmunoblastic lymphoma (25%). Immunohistochemistry is a useful and necessary diagnostic modality and helps subdivide prognostically different types of non-Hodgkin's lymphoma.     

Flow cytometry as an adjunct to cytomorphologic analysis of serous effusions

The role of flow cytometry (FC) in the diagnosis of lymphoid lesions by fine-needle aspiration (FNA) is well established. However, studies evaluating the usefulness of FC in serous cavity effusions (SCE) are few. We performed a retrospective review of 115 consecutive SCE with concurrent FC analysis, comparing the provisional cytopathologic diagnosis (PCD), i.e., before the FC results were added, with final diagnoses as modified by subsequent FC immunophenotyping. The predominant clinical indication for the FC analysis was the presence of a spontaneous SCE in a patient with a history of malignant lymphoma. Three- or four-color analysis was performed using antibodies against CD45, CD71, CD33, CD22, CD19, CD20, kappa, lambda, CD5, CD3, and CD56. The PCD was benign in 47%, atypical in 16%, and malignant in 37% of cases. The latter category consisted mostly of malignant lymphoma (n = 32), but also included acute lymphoblastic leukemia (1 case), T-cell lymphoma/leukemia (2 cases), acute myelogenous leukemia (1 case), multiple myeloma (1 case), Hodgkin's lymphoma (1 case), sarcoma (1 case), and adenocarcinoma (4 cases). In 18 cases (16%), the PCD was later modified by the FC results from atypical/suspicious to benign (8) and from benign or atypical/suspicious to malignant (10 cases). The latter group included acute natural killer (NK) cell leukemia (1 case), chronic lymphocytic leukemia (1 case), mantle cell lymphoma (2 cases), follicular lymphoma (3 cases), angioimmunoblastic lymphoma (1 case), large cell lymphoma (1 case), and multiple myeloma (1 case). As expected, FC was noncontributory in cases of Hodgkin's lymphoma and nonlymphoid malignancies. In summary, immunophenotyping by FC modified the PCD significantly in 16% of SCE, permitting appropriate cancer staging and management. The above data underscore the importance of FC as an adjunct to cytomorphology in SCE.     

Bone marrow infiltration of CD20-negative follicular lymphoma after rituximab therapy: a histological mimicker of hematogones and B-cell acute lymphoblastic leukemia/lymphoma

Rituximab is a monoclonal antibody against CD20. Rituximab combined with CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy, termed R-CHOP, have improved the overall survival of patients with B-cell lymphoma in comparison with that of CHOP therapy. However, as with other molecularly-targeted therapies, resistance to rituximab could emerge sooner or later after rituximab administration. A number of mechanisms for rituximab resistance have been proposed, including downregulation of CD20 protein expression. Differential diagnosis of B-cell proliferation with reduced or lost CD20 expression includes not only B-cell lymphomas with CD20 downregulation, but also other tumorous and non-tumorous lesions. These include precursor B-cell neoplasms such as B acute lymphoblastic leukemia/lymphoblastic lymphoma (B-ALL/LBL) and hematogones, a normal precursor B-cell proliferation during regeneration of hematopoiesis, typically observed following bone marrow suppression by chemotherapy. It is important to distinguish these possibilities because distinct therapies are required for each. In this paper, we report a case where bone marrow infiltration of follicular lymphoma histopathologically mimicked hematogones or B-ALL/LBL when CD20 expression was downregulated in follicular lymphoma after R-CHOP therapy.     

Primary appendiceal precursor B lymphoblastic lymphoma with peculiar morphology mimicking diffuse large B cell lymphoma

Precursor B lymphoblastic neoplasm usually presented as childhood leukemia. Most precursor lymphoblastic lymphoma are T‐cell lineage and precursor B lymphoblastic lymphoma constitutes only about 10% of cases according to the WHO Classification of Tumours of Haematologic and Lymphoid Tissues. The most frequent sites of involvement in precursor B lymphoblastic lymphoma are the skin, soft tissue, bone and lymph nodes. Primary appendiceal involvement is an uncommon condition. We present an unusual case of primary appendiceal precursor B lymphoblastic lymphoma in an 11‐year‐old boy with peculiar histological morphology mimicking diffuse large B cell lymphoma. Histologically, the tumor was composed of diffusely infiltrated large cells from mucosa and extended to the subserosal area. The tumor cells were positive to CD79a, CD20, PAX5, BCL2, CD10, TdT, p53 but not to CD3, BCL6 and CD34 by immunohistochemical studies. The response to conventional treatment regimen for lymphoblastic lymphoma was not good, with early relapse within three months. Partial remission was achieved by adding rituximab. Unfortunately, the patient died in ten months due to uncontrolled relapsed disease with generalized lymphadenopathy and massive pleural effusion. The special morphologic changes and poor response to chemotherapy may be related to the overexpression of p53.     

Primary bony peripheral T-cell lymphoma mimicking nasal type NK/T-cell lymphoma: a case report

Primary bony lymphomas are rare, and nearly all are high-grade B-cell lymphomas. Natural killer (NK)/T-cell lymphomas are highly aggressive lymphomas of NK- or T-cell lineage with predominant extranodal presentation and are divided into nasal and nasal-type (extra-nasal). We report a primary bony peripheral T-cell lymphoma mimicking NK/T-cell lymphoma, nasal type. A 22-year-old Taiwanese male presented with a frontal skull bone mass noted for 3 weeks, and received craniectomy with tumor removal. His tumor showed extensive coagulative necrosis with angioinvasion by large lymphoma cells expressing CD2, CD8, CD16, CD43, CD45, CD45RO, CD56, T-cell intracellular antigen-1, and granzyme B, but not CD3, CD4, CD20, CD57, CD68, and betaF1. In situ hybridization for Epstein-Barr virus-encoded mRNA was negative. Polymerase chain reaction study of formalin-fixed tissue showed clonal rearrangement of the T-cell receptor-gamma chain gene. The diagnosis was peripheral T-cell lymphoma, unspecified subtype. The initial stage was I(EA). His lymphoma was refractory to chemotherapy, and bony metastases developed in the right iliac bone 2 months later. He died of disease after 6 months without autopsy. We emphasize the importance of detailed immunohistochemical and gene rearrangement studies for the classification of malignant lymphomas via a very rare primary bony lymphoma of peripheral T-cell subtype.     

Cases of cutaneous and nasal CD56 (NCAM)-positive lymphoma in Japan have differences in immunohistology, genotype, and etiology.

CD56 (NCAM)-positive lymphoma frequently involves the skin and nasal area. This study shows it is likely that the clinicopathologic features of this lymphoma are distinctive to each of the primarily involved sites. Sixteen cutaneous and 11 nasal cases of CD56-positive lymphoma were examined. In 10 cutaneous cases, the lesions consisted of pleomorphic large-cell lymphoma that expressed CD3epsilon (CD3), CD2 (LFA2), CD4, CD122 (IL-2B receptor), TIA1, perforin, and granzyme B and displayed angiocentric/angiodestructive features. Lobular panniculitis was found in 8 of these cases, and 6 cases showed other organ involvement. The remaining 6 cutaneous cases consisted mostly of CD3epsilon- and CD4-positive, CD2-, CD122-, and TIA1-negative large blastic lymphoma, having less angiodestruction and panniculitis. Bone marrow invasion and leukemic changes were found in 4 of these cases during the clinical course. All 11 nasal cases showed pleomorphic small and medium-size lymphoma cells with angiodestructive features and were positive for CD3epsilon, CD2, CD122, TIA1, perforin, and granzyme B. CD4-positive lymphoma was found in 4 of these cases. Only 3 nasal cases showed other organ involvement. Genotypically, 2 of the 4 cases examined in the first cutaneous group, 3 of the 4 cases examined in the second cutaneous group, and only 1 of the 11 nasal cases showed rearrangement of the TcRCbeta gene by the Southern blot method. Only 2 cutaneous cases with panniculitis and all 11 nasal cases showed a positive nuclear signal for EBV-encoded RNA (EBERs) by in situ hybridization. Thus, two types of cutaneous CD56-positive lymphoma were found, each having a unique cell characteristic, genotype, and EBV infection pattern that differed from that of nasal-type lymphoma.     

Angiocentric immunoproliferative lesion and angiocentric lymphoma of lymph node in children. A report of two cases

AIM: To report two examples of an angiocentric immunoproliferative lesion (AIL) and angiocentric angiodestructive lymphoma (AL) presenting in lymph nodes in children. Most commonly involving extranodal sites, AIL/AL rarely presents in the spleen and lymph nodes. METHODS/RESULTS: Case 1 presented as a cervical lymphadenopathy in a 3 year old girl being treated for pre-B cell acute lymphoblastic leukaemia. Histological and immunohistochemistry studies revealed an Epstein-Barr virus positive (EBV+), large B cell (CD20 and CD30+) AIL with large areas of necrosis, the whole resembling lymphomatoid granulomatosis. Case 2 presented as a large supraclavicular lymphadenopathy in a 13 year old boy. Histology and immunohistochemistry revealed an EBV-, large T cell (CD45RO, CD56, and CD30+) AL, presenting the features of so called angiocentric T cell/natural killer cell lymphoma, nasal type. CONCLUSIONS: The term AIL/AL refers to a heterogeneous group of conditions not unique to a particular type of lymphoid cell. These lesions are easily recognised by the histopathologist because of their extremely unusual angiocentric pattern. Although rare, AIL/AL may present as nodal lesions in children ab initio.     

Anaplastic large cell lymphomas presented as bone lesions: a clinicopathologic study of six cases and review of the literature.

Non-Hodgkin's lymphomas uncommonly present as bone lesions. Most of these tumors are diffuse large B-cell lymphomas. Anaplastic large cell lymphoma (ALCL) presented as bone lesions is exceedingly rare. In this study, we describe six cases of ALCL that presented as solitary or multiple bone lesions. The average patient age was 33 years (range, 4 to 63 years) and the male to female ratio was 2:1. Fever and localized bone pain were the most frequent presenting symptoms. Radiologic examinations revealed osteolytic lesions in all cases, with three (50%) being multiple lesions and five (83%) involving the axial bones. All patients were initially assessed to have only bone involvement. Staging studies revealed mild cervical lymphadenopathy in one patient and no evidence of extraskeletal disease in the other five patients. Histologically, there was diffuse infiltration of one or more bones by large pleomorphic lymphoma cells. Immunohistochemical studies showed all six neoplasms were positive for CD30, EMA, and granzyme B. One case was of T-cell lineage, positive for CD3. One case was positive for the T-cell-associated antigen CD4. The remaining four cases were of null-cell type. In-situ hybridization for EBV was performed in five cases; all were negative. Despite the relatively low International Prognostic Index (IPI) of these patients (mean, 1.67; range, 1 to 3), the overall prognosis was relatively poor: three of six died of disease within 2 years of diagnosis, and two of six were alive with evidence of disease (follow-up, 6 mo to 2 years). Thus, compared to their nodal counterparts, ALCLs that present as bone lesions are distinguished by their uniform expression of EMA and granzyme B, and a relatively poor clinical outcome. Our results also suggest that ALK-1 expression in this clinical setting is not a favorable prognostic indicator.     

CD5-positive mucosa-associated lymphoid tissue (MALT) lymphoma: a clinicopathologic study of 14 cases

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) is a B-cell neoplasm that is typically CD5 negative. We describe the clinicopathologic, immunophenotypic, and cytogenetic features of 14 cases of CD5+ MALT lymphoma. There were 9 men and 5 women (median age, 68 years; range, 34-87 years). MALT lymphoma was initially diagnosed in salivary glands (n = 4), nasopharynx (n = 2), and 1 case each in conjunctiva, thyroid, stomach, colon, skin, lung, kidney, and retroperitoneum. Two patients had localized disease; 9 had disseminated disease with generalized lymphadenopathy (n = 8), multifocal lymphoma (n = 6), or bone marrow involvement (n = 5). No staging information was available for the remaining patients. None presented with B symptoms, splenomegaly, cytopenias, lymphocytosis, monoclonal gammopathy, or elevated serum lactate dehyrogenase. Serum β2-microglobulin was elevated in 6. Morphologically, the neoplasms had features typical of MALT lymphoma being composed of small- to medium-sized cells with round to slightly irregular nuclear contours and moderate amount of cytoplasm. Lymphoepithelial lesions were noted in 4 cases. CD5 was positive in all cases by immunohistochemistry (n = 12) and/or flow cytometry (n = 11). All cases assessed were negative for cyclin D1 (13/13) and CD10 (11/11). Conventional cytogenetics in 7 cases showed trisomy 3 in 3 and diploid in 4. With a median follow-up of 71 months (range, 2-131 months), overall survival at 5 years was 100%, although 5 patients required chemotherapy. Our results show that CD5 expression is rare in MALT lymphoma, and is often associated with nongastric disease and an increased tendency to present with disseminated disease. Overall survival is excellent with appropriate therapy.     

American Registry of Pathology Expert Opinions: Immunohistochemical evaluation of classic Hodgkin lymphoma

The diagnosis of classic Hodgkin lymphoma requires immunohistochemical confirmation in most cases and one can argue for these studies as standard-of-care in the diagnostic workup. The authors propose a panel of studies for primary identification of CHL to include: CD3, CD20, CD15, CD30 and PAX5. When pattern discordances are identified, additional assessment is recommended. In the case of overexpression of B lineage markers by Hodgkin/Reed-Sternberg cells, or a differential diagnosis that includes large B-cell lymphoma or variants, additional markers recommended are: CD45, OCT2, BOB1, CD79a and MUM1/IRF4. If primary mediastinal large B cell lymphoma is considered in the differential diagnosis, suggested additional markers include: P63, CD23, CD45 and CD79a. When considering a differential diagnosis that includes anaplastic large cell lymphoma we suggest: ALK, CD45, pan T cell antigens (such as CD2, CD5, CD7, and CD43), and cytotoxic markers (granzyme, perforin, and TIA1). If peripheral T cell lymphoma or T cell lymphomas of follicular helper origin are considered in the differential diagnosis, the following panel is recommended: pan T cell antigens, CD4, CD8, one or more follicular dendritic cell markers, and assessment for Epstein-Barr virus (EBV) infection, preferably EBV encoded RNA (EBER) as assessed by in situ hybridization When the differential diagnosis includes nodular lymphocyte predominant Hodgkin lymphoma, recommended additional studies include OCT2, CD21 and/or CD23, PD1, and assessment for EBV infection. The authors recognize that these panels may not be adequate to completely characterize other lymphomas, but these panels will usually be sufficient to distinguish classic Hodgkin lymphoma from other lymphoma types.     

Lineage determination of CD20- B-Cell neoplasms: an immunohistochemical study

We studied 61 CD20- B-cell lymphomas, including 29 cases of precursor B-cell lymphoblastic leukemia/lymphoblastic lymphoma (B-ALL/B-LBL), 25 cases of CD20- recurrent mature B-cell lymphoma after rituximab therapy, and 7 cases of CD20- diffuse large B cell lymphoma (DLBCL). We used markers specific for B lineage: CD79a, Pax-5, OCT.2, and BOB.1. All B-ALL/B-LBLs expressed Pax-5 (29/29 [100%]), 25 (93%) of 27 expressed BOB.1, 23 (79%) of 29 expressed CD79a, and 6 (22%) of 27 expressed OCT.2. The percentages of cases expressing Pax-5, CD79a, OCT.2, and BOB.1 in CD20- recurrent mature B-cell lymphomas after rituximab treatment were 88% (21/24), 84% (21/25), 81% (17/21), and 73% (16/22), respectively. CD20- DLBCLs rarely express routine B-lineage markers, such as and CD79a and Pax-5, but they expressed OCT.2 or BOB.1. Pax-5, BOB.1, and CD79a antigens are the most reliable B-lineage markers for paraffin immunophenotyping B-ALL/B-LBL. CD79a and Pax-5 should be used as the first-line B lineage-specific markers for rituximab-treated CD20- mature B-cell lymphomas. If negative, OCT.2 or BOB.1 may be useful. The newly identified B-lineage markers, OCT.2 and BOB.1, may be the most useful for the B-lineage determination of CD20- plasmablastic or primary effusion subtypes of DLBCL.     

Immunoarchitecture of normal human bone marrow: a study of frozen and fixed tissue sections.

To provide baseline information on the immunoarchitecture of normal bone marrow, we studied cryostat-cut, frozen, and paraffin-embedded, fixed tissue sections prepared from 21 core biopsies of normal bone marrow obtained during bone marrow harvests for transplantation. A large panel of antibodies was applied that included, for frozen tissue, Leu-6 (CD1), T11 (CD2), Leu-3a (CD4), Leu-1 (CD5), Leu-2a (CD8), J5 (CD10), My7 (CD13), Leu-11 (CD16), B4 (CD19), B1 (CD20), B2 (CD21), Tac (CD25), My9 (CD33), T200 (CD45), NKH-1 (CD56), kappa and lambda chains, beta F1, Ki-67, HLA-DR, TQ1, and keratin, and for fixed tissue, leukocyte common antigen (CD45), L26 (CD20), LN1 (CDw75), LN2 (CD74), LN3, LN4, LN5, MB1 (CD45R), MB2, MT1 (CD43), MT2 (CD45R), UCHL1 (CD45R0), BM1, Ki-1 (CD30), Leu-M1 (CD15), lysozyme, KP1 (CD68), actin, S100, neuron-specific enolase, vimentin, and keratin. On fresh-frozen sections CD19 and CD2 were the most reliable and sensitive markers for B and T cells, staining 5% and 9% of marrow cells, respectively. Immunoglobulins generally showed heavy background staining, which frequently precluded an accurate assessment. The CD4 to CD8 ratio in the bone marrow was reversed from that of peripheral blood. On fixed tissues, leukocyte common antigen was found in 14% of the marrow cells, corresponding roughly to the lymphocyte population. L26, a pan-B-cell marker, stained 3% of the marrow cells. Among the other B-cell markers, LN1 and MB2 stained a large number of cells (40% to 70%), indicating reactivity with cells of the myeloid or erythroid series in addition to lymphocytes. Among the T-cell markers, UCHL1 and MT1 stained 66% and 50% of the cells, respectively, which could be explained by their cross-reactivity with myeloid cells. Nonspecific myelomonocytic markers (Leu-M1, KP1, and lysozyme) also showed reactivity in a high percentage of cells. No particular architectural distribution patterns of B or T lymphocytes were noted in either frozen or fixed bone marrow specimens. The results of this study provide normal baseline data for the immunohistologic application of hematopoietic and lymphoid markers on frozen or fixed bone marrow biopsy specimens.     

Childhood non-Hodgkin lymphomas in the United Kingdom: findings from the UK Children's Cancer Study Group.

AIM: To review the presenting clinical features and the histology of cases of non-Hodgkin lymphoma (NHL) entered into the United Kingdom Children's Cancer Study Group NHL Trial. METHODS: Sections of biopsy specimens from all cases entered into the trial were stained with Giemsa and haematoxylin and eosin. All cases were stained immunohistochemically for CD45, CD3, CD45RO, CD20, and CD30. Sections were stained with either naphthol AS-D chloroacetate esterase or KP1 (CD68) to identify granulocytic tumours. In a minority of cases, additional immunohistochemical stains were performed when necessary to establish the diagnosis. The sections were reviewed by three pathologists. RESULTS: Of 308 cases analysed, 293 were categorised as NHL. There was only one case of low grade lymphoma in the series. Over 80% of the cases fell into the categories Burkitt lymphoma (42.2%), lymphoblastic lymphoma (27.2%) and anaplastic large cell lymphoma (15.1%). Cases of Burkitt lymphoma presented most often with abdominal tumours mainly of the ileocaecal region. Tumours of the oropharynx and nasopharynx were also common in this group. Of the 84 lymphoblastic lymphomas, 56 were of the T-cell phenotype, 12 of the B-cell phenotype and 16 of indeterminate lineage. Most of the T-lymphoblastic lymphomas showed mediastinal or pleural involvement. Infiltration of the skin and soft tissues was seen in 25% of lymphoblastic lymphoma of B or indeterminate phenotype. Forty six children were diagnosed as having anaplastic large cell lymphoma, the majority being of T or indeterminate lineage. Most patients presented with lymphadenopathy but involvement of the bones, soft tissues or skin was seen in seven patients and of the mediastinum and lungs in five. CONCLUSION: Childhood non-Hodgkin lymphomas are almost all high grade and frequently extranodal. They fall mainly into the categories Burkitt lymphoma, lymphoblastic lymphoma and anaplastic large cell lymphoma. The separation of these subcategories can be made on the basis of morphology and immunohistochemical features. The anatomical distribution of these different categories of non-Hodgkin lymphoma is distinctive.     

原发淋巴结套细胞淋巴瘤临床病理分析

目的：探讨原发淋巴结套细胞淋巴瘤（MCL）的临床病理与免疫组化特点。方法：收集6例淋巴结MCL,免疫组化ABC法确定肿瘤细胞特征,使用的抗体有CD45、CD20、CD79、CD45RO、CD30、CD68、TdT、CD43、CD5、cyclinD1、c-myc,IgD,IgM等。结果：光镜可将MCL分为4种亚型：套区型1例,结节型1例,弥漫型2例,母细胞化型2例。肿瘤细胞表达全B细胞标记,IgD CD43 ,cyclinD1(5/6),CD5(4/6) 。结论：MCL是一种具有特殊免疫表型的B细胞淋巴瘤,不同的组织学构型其预后可能不同,临床应与其它类型B细胞淋巴瘤鉴别,如淋巴结边缘区B细胞淋巴瘤（MZL）,滤泡性淋巴瘤（FL）及CLL／SLL等鉴别。     

Immunoreactivity of MIC2 (CD99) in acute myelogenous leukemia and related diseases.

MIC2 is characteristically expressed in lymphoblastic lesions and Ewing's/primitive neuroectodermal tumor sarcomas. Although MIC2 has recently been reported in chloroma and rare terminal deoxynucleotidyl transferase-positive acute myelogenous leukemia (AML), the incidence and the significance of MIC2 (CD99) immunoreactivity in myeloid lesions is not clear. In this study, we evaluated MIC2 positivity in a variety of myeloid diseases and normal marrow to determine its incidence and distribution in myeloid diseases; its correlation with flow cytometric and cytogenetic data in AML; and its association with leukemic transformation, relapse, and chloroma formation. Paraffin sections of 11 chloromas and 94 bone marrow core biopsies from 66 patients were stained with CD99 monoclonal antibody 12E7. Of 94 bone marrow core biopsies, there were 30 AML (fragment antigen binding M0 to M6), 23 remissions, 5 relapses, 12 myeloproliferative disorders, 13 myelodysplastic syndromes, and 11 normal marrows from patients who did not have leukemia. CD99 immunoreactivity was evaluated with light microscopy. MIC2 expression was seen in leukemic blasts in 6 of 11 chloromas (55%) and 13 of 30 AML (43%) but rarely in myeloproliferative disorders, myelodysplastic syndromes, remission, and normal marrow. CD99 tended to be positive in M1-, M3-, and HLA-Dr-negative AML and negative in AML with relapse. MIC2 expression did not correlate with the karyotype independent of French-American-British Cooperative Group classification and the disease remission or occurrence of chloroma in AML. We concluded that MIC2 is commonly expressed in leukemic blasts of AML and is not predictive of leukemic transformation from myeloproliferative disorders and myelodysplastic syndromes or chloroma formation. Caution should be taken when using MIC2 as a marker for Ewing's sarcoma/ primitive neuroectodermal tumor or lymphoblastic lymphoma on paraffin sections of either soft tissue or bone marrow specimens.     

Histological and immunophenotypic profile of nasal NK/T cell lymphomas from Peru: high prevalence of p53 overexpression.

Nasal NK/T-cell lymphoma is a unique form of lymphoma highly associated with Epstein-Barr virus (EBV). These lymphomas are rare in Western populations and much more prevalent in some Asian and Latin American countries. Although there are several sizable studies from Asian countries, the same is not true from South America. The aim of this study was to analyze a series of 32 cases of nasal T-cell lymphoma from Peru and to further extend the characterization of this disease. Immunohistochemistry was performed on paraffin sections using the following antibodies: CD20 (L26), CD45RO, CD3, Ki67, CD57, CD56, TIA-1, bcl-2, and p53. The presence of EBV was investigated with immunohistochemical analysis for latent membrane protein (LMP)-1 and in situ hybridization using an antisense riboprobe to EBER 1. The 32 patients included 18 men and 14 women (M:F ratio, 1.2:1), with a median age of 43 years (11 to 72). Three categories were identified: (1) Nasal NK/T cell lymphomas (28 cases): The morphology ranged from small or medium-sized cells to large transformed cells. Necrosis was present in 86% of the cases, and angioinvasion was seen in 36% of the cases. All cases were positive for CD45RO, CD3, and for TIA-1. CD56 was positive in 21 of 27 cases (78%), and CD57 was negative in all cases. EBER 1 positivity was identified in most of the tumor cells in 27 of 28 cases (96%), including the six cases in which CD56 was negative. Overexpression of p53 was detected in 24 cases (86%). (2) Blastic NK cell lymphoma (1 case): The neoplastic cells resembled those of lymphoblastic lymphoma. CD56 and CD45RO were positive; TIA-1, TdT, and EBER-1 were negative. (3) Peripheral T-cell lymphoma (PTCL) unspecified (3 cases): CD56, TIA-1, and EBER-1 were negative. Nasal lymphomas from Peru with a T cell phenotype are predominantly EBV-associated NK/T cell lymphomas, similar to those described in Asian countries. The expression of CD56, TIA-1, and EBER-1, in combination, are very useful markers for the diagnosis of nasal NK/T cell lymphoma in paraffin-embedded tissue. The differential diagnosis of T-cell lymphomas in the nasal region should include rare cases of PTCL unspecified and the blastic variant of NK cell lymphoma. P53 is overexpressed in 86% of the cases. The significance of this finding with regard to clinical behavior and prognosis remains to be determined.     

T-cell blast crisis of chronic myelogenous leukemia manifesting as a large mediastinal tumor

We report an unusual case of T-cell blast crisis of chronic myelogenous leukemia (CML) with a clinical presentation more typical of de novo T-cell lymphoblastic lymphoma. The patient was a 32-year-old man who presented with acute superior vena cava syndrome 19 months after an initial diagnosis of CML and 5 months after allogeneic bone marrow transplantation. The tumor was composed of primitive lymphoid cells expressing CD2, CD3, CD4, CD5, CD7, CD8, and CD10. Although the clinical features were more typical of acute lymphoblastic leukemia/lymphoma, fluorescence in situ hybridization analysis showed the bcr-abl fusion gene within blastic tumor cells. This finding confirmed that the mass represented a blastic transformation of CML. We use the unusual features of the current case and the previous reports to suggest that the development of T-cell blast crisis of CML is dependent on the presence of both marrow and extramedullary disease and a mechanism to evade apoptosis.     

Ewing sarcoma vs lymphoblastic lymphoma. A comparative immunohistochemical study

To develop a practical immunohistochemistry panel for distinguishing lymphoblastic lymphoma from Ewing sarcoma (ES), we evaluated 17 ES and 27 lymphoblastic lymphoma and leukemia cases with antibodies to CD99, terminal deoxynucleotidyl transferase (TdT), leukocyte common antigen (LCA), CD43, CD79a, CD20, CD3, vimentin, and neuron-specific enolase (NSE). Three cases were bone lymphomas, 2 initially misdiagnosed as ES. All cases were CD99+. All lymphomas and leukemias were TdT+ compared to none of the ESs. None of the ESs expressed other lymphocytic markers, which were inconsistently expressed in the lymphomas and leukemias: CD43, 33%; LCA, 30%; CD79a, 19%; CD3, 19%; and CD20, 7%. Of the ESs, 88% were vimentin positive compared with 23% of lymphomas and leukemias. Vimentin was stronger and more diffuse in ES. NSE did not reliably stain any cases. When faced with the differential diagnosis of ES vs lymphoblastic lymphoma, an immunohistochemical panel that includes antibodies to CD99 and TdT is useful. Both epitopes are well preserved in fixed and decalcified tissue. A panel composed of antibodies to CD99 and TdT, in conjunction with other lymphocytic markers and vimentin, is highly sensitive and specific.     

Lymphoma of the breast. A clinicopathologic study of primary and secondary cases

BACKGROUND: Primary lymphomas of the breast are rare, accounting for 1.7% to 2.2% of extranodal lymphomas and 0.38% to 0.7% of all non-Hodgkin lymphomas. Although secondary breast lymphomas are also rare, they represent the largest group of metastatic tumors of the breast. OBJECTIVES: To investigate the clinicopathologic and immunophenotypic characteristics of breast lymphomas, the relative frequency of primary and secondary mammary lymphomas, and in selected cases, the role of gene rearrangement analysis in diagnosis and staging of these lymphomas. RESULTS: We conducted a retrospective review of 22 cases of breast lymphoma diagnosed at William Beaumont Hospital, Royal Oak, Mich, during a 30-year period (1963-1994). Eleven of the 22 cases fulfilled the criteria for primary breast lymphoma; these cases represented 0.6% of all non-Hodgkin lymphomas seen in our hospital. Of the 11 cases, 5 were diffuse large B-cell lymphomas, 2 were follicle center lymphomas, 2 were marginal zone B-cell lymphomas (mucosa-associated lymphoid tissue type), 1 was a lymphoplasmacytoid lymphoma, and 1 was a peripheral B-cell neoplasm, unclassified. Using a panel of immunohistochemical stains (CD45RO, CD45RA, CD43, CD3, CD20, CD30, CD68, and HLA-DR), 8 cases demonstrated unequivocal B-cell phenotype and 3 cases had equivocal or weak staining patterns for B-cell markers. We identified no cases of T-cell lymphoma. Of 7 cases that had bone marrow biopsies for staging, 3 were positive morphologically for bone marrow involvement. Molecular analysis of B- and T-cell gene rearrangement was used to exclude bone marrow involvement in one case with bone marrow lymphoid aggregates and to confirm negativity in a case that was morphologically negative. Of the 11 secondary breast lymphomas, 5 were diffuse large B-cell lymphomas; 1 was diffuse large B-cell, primary mediastinal subtype; and 5 were follicle center lymphomas. CONCLUSIONS: Breast lymphomas represented 1.2% of all non-Hodgkin lymphomas in this study; the frequency of primary and secondary cases was equal. In both groups, right breast lesions were predominant, and the most frequent morphologic type was diffuse large B-cell lymphoma. Gene rearrangement analysis is helpful in selected cases to rule out bone marrow involvement, especially in older patients, in whom lymphoid aggregates are common.