Monoclonal antibody HML-1 reactivity with adult T-cell leukaemia/lymphoma and other lymphomas

Human T-cell leukaemia/lymphoma virus type 1 (HTLV-1), a causative virus of adult T-cell leukaemia/lymphoma (ATLL), is known to be transmitted by breast-feeding. Using a monoclonal antibody HML-1 which labels human intestinal intra-epithelial T lymphocytes, we have immunohistochemically examined ATLL tissues in order to evaluate the possibility that HTLV-1 infected intestinal T cells are the origin of ATLL cells. Previously this antibody was reported to react with intestinal T-cell malignant lymphomas but not with peripheral tumours, or any B-cell lymphomas. We investigated 181 patients with malignant lymphomas and found that 19 out of 113 ATLLs were positive for HML-1. T-cell malignant lymphomas excluding ATLL also reacted with HML-1 (7/24), but all the B-cell lymphomas 0/33) and non-neoplastic lymph node and skin lesions (0/10) were negative for HML-1. In patients with ATLL and other T-cell malignant lymphomas, the positivity level of HML-1 was relatively higher in stomach (3/7) and tonsil (2/6) than that in lymph nodes (15/100) and skin (8/47). We observed one HML-1 positive ATLL patient with tumour formation in the skin and lymphadenopathy and marked infiltration of the large intestine but minimal involvement of other organs. Although HML-1 was frequently expressed in gastric infiltration of ATLL, the level of positivity was too low in lymph nodes to support the hypothesis that HTLV-1 infected intestinal T cells are the origin of ATLL cells. Some of the HML-1 positive ATLL cases co-expressed CD30. Furthermore, three of six cases of Ki-1 lymphoma (large anaplastic cell lymphoma) were positive for HML-1. We conclude that expression of HML-1 in ATLL reflects an activated state of the lymphoma cells, but not the intestinal origin of ATLL cells.     

B-cell and T-cell lymphomas of the breast: clinical--pathological features of 53 cases

Breast involvement by non-Hodgkin lymphomas is rare. We studied the morphological, immunophenotypical, and clinical features of 53 cases of malignant lymphomas involving the breast in a population of Brazilian patients. Most of the cases were of B-cell phenotype. Four of the patients with primary breast lymphomas had T-cell lymphomas, 3 had CD30-positive anaplastic large cell lymphomas, and 1 had panniculitis-like T-cell lymphoma. Most patients presented with an incidental breast mass. Secondary breast lymphoma was seen in 19 patients and most commonly occurred as part of widespread nodal disease. Two patients presented with bilateral breast involvement. The most prevalent histological subtype was also diffuse large B-cell lymphoma, followed by follicular lymphoma. This study shows that the broad morphological and immunophenotypical spectrum of malignant lymphoma of the breast occurring in a large series of Brazilian patients has many similarities with that seen in Western countries, with a higher proportion of high-grade lymphomas in both primary and secondary cases.     

Monoclonal antibodies reactive in routinely processed tissue sections of malignant lymphoma, with emphasis on T-cell lymphomas

The immunoreactivity of eight monoclonal antibodies was evaluated on 45 routinely processed lymphomas (22 T-cell lymphomas, 11 B-cell lymphomas, and 12 cases of Hodgkin's disease). Two antibodies reactive with leukocyte common (T200) antigens (PD7/26 and 2B11) stained most of the B- and T-cell lymphomas but did not stain the Reed-Sternberg cells and variants in Hodgkin's disease. Two antibodies known to stain B cells (LN-1 and LN-2) reacted with some of the B-cell lymphomas, but LN-2 also reacted with the neoplastic cells in six of 22 T-cell lymphomas and with the Reed-Sternberg variants in eight of 12 cases of Hodgkin's disease. The granulocyte antibody anti-Leu M1 reacted with most cases of Hodgkin's disease but also reacted with two of 11 B-cell non-Hodgkin's lymphomas. An antibody to epithelial membrane antigen (anti-EMA) stained some cases of T-cell lymphoma, B-cell lymphoma, and Hodgkin's disease. Leu 7 was expressed in one T-cell lymphoma and in one case of Hodgkin's disease. A novel antibody reactive with T cells (L60) stained all cases of T-cell lymphoma but also stained some cases of B-cell lymphoma and one case of Hodgkin's disease. We conclude that none of these antibodies, when used alone on routinely fixed paraffin-embedded material, is completely sensitive and specific for T-cell lymphoma, B-cell lymphoma, or Hodgkin's disease. However, a panel of antibodies is useful in distinguishing Hodgkin's disease from non-Hodgkin's lymphoma and in suggesting the B- or T-cell phenotype of non-Hodgkin's lymphomas.     

Non-HTLV-1-associated primary gastric T-cell lymphomas show cytotoxic activity: clinicopathological,immunohistochemical characteristics and TIA-1 expression in 31 cases

AIMS: Most primary gastrointestinal lymphomas are of B-cell origin and T-cell origin is very rare. Recent studies have suggested that human T-cell lymphotrophic virus type 1 (HTLV-1) may be involved in the development of primary gastric T-cell lymphoma. We analysed 31 patients with primary gastric T-cell lymphoma in south-west Japan, an area endemic for HTLV-1, and determined their phenotypes, genotypes, and HTLV-1 status. METHODS AND RESULTS: Here we present 31 cases of primary gastric T-cell lymphoma in a HTLV-1-endemic area in Japan and analyse the clinical status, histology, phenotype and virus status. The median age at onset of primary gastric T-cell lymphoma was 57 years with a gender ratio of M:F = 1.58:1. Six of the 31 primary gastric T-cell lymphoma cases had HTLV-1 proviral DNA (five males, one female), nine of the 31 cases were positive for anti-adult T cell leukaemia antibody, without examination of HTLV-1 proviral DNA (five males, four females), eight were non-HTLV-1-associated primary gastric T-cell lymphoma (four males, four females) and the other eight cases were unknown. Primary gastric T-cell lymphoma usually presented as a large ulcerated tumour at the corpus to the antrum and histologically consisted of anaplastic large cell type (n = 2), pleomorphic large cell type (n = 3), pleomorphic medium and large cell type (n = 14), pleomorphic medium cell type (n = 11), and angioimmunoblastic T-cell lymphoma type (n = 1). There were no clear macroscopic and microscopic differences between HTLV-1-associated and non-HTLV-1-associated primary gastric T-cell lymphoma. Most patients died within 2 years of diagnosis, and both types of primary gastric T-cell lymphoma (with and without HTLV-1) were associated with poor prognosis. Cytotoxic marker analysis showed that HTLV-1-associated lymphomas were negative for TIA-1, while non-HTLV-1-associated lymphomas were positive for TIA-1. CONCLUSIONS: Our results suggest that in HTLV-1-endemic areas, patients with HTLV-1-associated primary gastric T-cell lymphoma should be managed carefully and that TIA-1 seems to be useful for identifying the aetiology of this lesion.     

Sinonasal non-Hodgkin's lymphomas and Wegener's granulomatosis: A clinicopathological study

Summary Reports of sinonasal non-Hodgkin's lymphomas, analysed with monoclonal antibodies, are scarce, and differentiation of these lymphomas from Wegener's granulomatosis can be difficult. In this study, we investigated histopathologically and immunohistologically 20 cases of non-Hodgkin's lymphoma, primary in the sinonasal region, and sinonasal biopsies from 11 patients with Wegener's granulomatosis. All T-cell lymphomas (n=7) and plasmacytomas (n=4) were stage I at clinical presentation, while all B-cell lymphomas (n=9) presented at higher stages. T-cell lymphomas tended to be more frequent in the nasal cavity and paranasal sinuses; B-cell lymphomas more often presented in the nasopharynx. Remarkably, 1 B-cell lymphoma expressed MT1, and 1 T-cell lymphoma expressed L26 (CD 20). The follow-up of 2 patients with a clinical diagnosis of Wegener's granulomatosis was suggestive of non-Hodgkin's lymphoma. Retrospective immunohistochemical analysis revealed that the original histological diagnosis of non-specific inflammation had to be changed to T-cell lymphoma, pleomorphic small cell type. We conclude that a biopsy from the sinonasal region with a dense inflammatory infiltrate, consisting predominantly of Tlymphocytes, renders a diagnosis of Wegener's granulomatosis unlikely and is at least suspicious of T-cell lymphoma. Immunohistochemical analysis is warranted for this type of biopsy.     

Primary gastric lymphomas: Morphologic, immunohistochemical and immunogenetic analyses

Morphologic, lmmunohistochemical and lmmunogenetic studies were performed on 28 cases of primary gastric lymphoma from fresh frozen tissue. Eight cases were diagnosed as diffuse large B-cell lymphoma, four as follicular center lymphoma (follicular), five as mucosa-associated lymphoid tissue (MALT) lymphoma, three as plasmacytoma, and three as T-cell lymphoma, two as mantle cell lymphoma, one as follicular center lymphoma (diffuse, predominantly small cell), and one as lymphoplasmacytoid lymphoma, and one as Hodgkin's disease.
From lmmunohistochemical studies, four types of morphologically similar low-grade lymphomas can be differentiated by a combination of various monoclonal antibodies. Cases of diffuse large B-cell lymphoma may have a germinal center origin. We observed lympho-epithelial lesions in cases of non-MALT lymphomas. We therefore consider that the current diagnostic criterion for MALT lymphoma may not always be valid.
Except for cases of T-cell lymphoma and Hodgkin's disease, 17 out of 22 cases revealed clonal rearrangement bands of the JH gene. In situ hybridization (ISH) and polymerase chain reaction (PCR) studies revealed the presence of Epstein-Barr (EB) virus genomes in two and three cases, respectively. Epstein-Barr virus may play a role in lympho-magenesis, although on relatively rare occasions.     

Peripheral T-cell lymphomas of the intestine.

Twenty-seven cases of primary peripheral T-cell lymphomas of the intestine (PTLI) were investigated. Seven patients had histories of malabsorption. The most frequent symptoms at presentation were weight loss, abdominal pain, and acute abdomen. The jejunum was the most common site of lymphoma and multifocal disease was found in 72% of the cases. Twenty-two patients (92%) presented with localized disease confined to the intestine and abdominal lymph nodes, only two patients had generalized disease. According to the pattern of lymphoma infiltration and the morphology of the uninvolved small intestinal mucosa, 21 cases were separated histologically into three categories; 1) enteropathy-associated T-cell lymphoma (EATCL, n = 9) showing predominant intramucosal lymphoma spread and villous atrophy of uninvolved mucosa with high density of intraepithelial lymphocytes (IEL), 2) EATCL-like lymphoma without enteropathy (EATCL-LLWE, n = 5) but with an infiltration pattern similar to EATCL, and 3) T-cell lymphoma without features of EATCL (Non-EATCL, n = 7). Distinctive features of EATCL were the high incidence of malabsorption states, multifocal intestinal disease in all cases, and the high frequency of intestinal recurrences. On frozen sections four of eight PTLI showed the phenotype CD3+ CD4- CD8- HML-1+, which is also expressed on a small subset of normal IEL. The morphologic and immunomorphologic findings suggest that the majority of PTLI is derived from mucosal T lymphocytes. This derivation may be responsible for certain biologic features, such as the preferential spread to and relapse of PTLI at small intestinal sites.     

Expression of the intestinal T-lymphocyte associated molecule HML-1: analysis of 75 non-Hodgkin''s lymphomas and description of the first HML-1 positive T-lymphoblastic tumour

The expression of the gut intra-epithelial T-cell associated molecule HML-1, a trimeric protein of 150, 125, 105 kD, was studied in 75 T-cell lymphomas of different subtypes: 20 T-lymphoblastic lymphomas/leukaemias; 50 nodal peripheral T-cell lymphomas; and five intestinal T-cell lymphomas. Our results confirm: (i) the usefulness of the HML-1 monoclonal antibody as an immunohistochemical marker for intestinal T-cell lymphomas: and (ii) the lack of reactivity of HML-1 with nodal peripheral T-cell lymphomas. Moreover, expression of the HML-1 molecule was found for the first time in a case of T-lymphoblastic lymphoma/leukaemia. The patient presented with a mediastinal mass which consisted of HML-1 + neoplastic cells displaying a phenotypic profile consistent with early thymocytes. Genes coding for the alpha, beta, gamma and delta chains of the T-cell receptor were in a germline configuration. The neoplastic cells could have been derived from the small subset of HML-1 + thymocytes detectable in the cortex of normal human thymus.     

Primary lymphomas of the lung: morphological, immunohistochemical and clinical features

Sixty-two cases of primary malignant lymphoma of the were investigated. Fifty-eight lymphomas were of B- and two of T-cell type. Two cases of high-grade homa could not be further classified. The largest group (43 cases) consisted of low-grade B-cell lymphoma of the bronchus-associated lymphoid tissue. These showed features similar to low-grade B-cell lymphomas of the mucosa-associated lymphoid tissue of the stomach. The low-grade lymphomas showed a peak occurrence in the sixth decade, the high-grade lymphomas in venth decade. Males predominated slightly. Three-quarters of the patients with low-grade B-cell lymphoma of the bronchus-associated lymphoid tissue showed solitary or multiple sharply defined nodules of the lung. The prognosis of the B-cell-derived lung lymphomas without constitutional symptoms was relatively favourable, regardless of whether they were of low- or high-grade malignancy, whereas patients with constitutional symptoms and the two patients with T-cell lymphomas showed a bad prognosis. However, recurrences and metastases in the lung, stomach, lymph nodes and salivary glands were seen in about 46% of the cases of low-grade B-cell lymphoma of the bronchus-associated lymphoid tissue.     

Primary cutaneous T-cell-rich B-cell lymphomas with flow cytometric immunophenotypic findings. Report of 3 cases and review of the literature

BACKGROUND: Primary cutaneous T-cell-rich B-cell lymphoma is a relatively rare entity that has been diagnosed most commonly using immunohistochemical and molecular techniques. Flow cytometric immunophenotyping (FCI) has not been described in this entity. We report the demonstration of B-cell monoclonality by FCI in 3 cases of primary cutaneous T-cell-rich B-cell lymphoma. METHODS: Clinical and pathologic data were recorded for 3 cases of primary cutaneous T-cell-rich B-cell lymphoma. Immunohistochemical and FCI data were available in all cases; DNA analysis was performed in 1 case. RESULTS: Flow cytometric immunophenotyping revealed a monoclonal B-cell population exclusively in the monocyte (large cell) region in all 3 cases. Immunohistochemistry confirmed the T-cell richness of the infiltrates within the cutaneous lymphomas; T cells accounted for 65% to greater than 90% of the cells within the infiltrates. DNA analysis by polymerase chain reaction in 1 case did not demonstrate a monoclonal rearrangement of the immunoglobulin heavy-chain gene. CONCLUSIONS: Flow cytometric immunophenotyping in primary cutaneous T-cell-rich B-cell lymphoma may be useful in demonstrating monoclonality in these cases, especially if there is selective gating on the relatively small population of cells in the large cell region. The FCI data should be correlated with histology and immunohistochemistry.     

Aberrant expression of T-cell-associated antigens on B-cell non-Hodgkin lymphomas

We describe 9 well-characterized cases of B-cell non-Hodgkin lymphoma (NHL) that showed aberrant expression of T-cell-associated antigens by 2-color flow cytometry. Cases were as follows: chronic lymphocytic leukemia/small lymphocytic lymphoma, 4; follicle center cell lymphoma, 2; mantle cell lymphoma, 1; and diffuse large B-cell lymphoma, 2. CD2 was the most commonly expressed antigen (5 cases). CD8 and CD7 were identified in 2 cases each, including 1 case that expressed both CD7 and CD4. The disease course and response to treatment were compatible with the type and stage of lymphoma. No unusually aggressive behavior was noted in any case. A control group of 59 cases of benign lymph nodes analyzed during the same period showed no aberrant expression of T-cell-associated antigens; thus, such expression is not a feature of benign lymphoid proliferations. Study of these B-cell lymphomas may prove invaluable to study aberrant activation of silent or repressed T-cell differentiation genes. CD2-expressing B-cell NHLs may represent clonal expansion of CD2+ B lymphocytes that normally constitute a small fraction of peripheral B lymphocytes and should not be confused with composite B- and T-cell lymphomas. Unless aggressive behavior is noted consistently, no aggressive treatment is justified.     

Epstein-Barr virus-associated B-cell lymphoproliferative disorders in angloimmunoblastic T-cell lymphoma and peripheral T-cell lymphoma, unspecified

Various patterns of Epstein-Barr virus (EBV)-associated B-cell lymphoproliferation occur in patients with immunodeficiency. We studied 17 cases of T-cell lymphoma displaying extensive EBV-driven B-cell lymphoproliferation or simultaneous/subsequent EBV-associated B-cell lymphoma. In 10 cases of angioimmunoblastic T-cell lymphoma, an uncommonly prominent population of EBV+ atypical, activated, focally confluent large transformed B cells was found in the background of T-cell lymphoma. In 4 cases, an EBV-associated B-cell neoplasm (3 diffuse large B-cell lymphomas, 1 plasmacytoma) occurred in patients with T-cell lymphoma. Three cases were composite lymphomas of a peripheral T-cell lymphoma, unspecified, combined with EBV-associated diffuse large B-cell lymphoma. The transformed B-cell population displayed EBV latency types 2 and 3. Monoclonal and oligoclonal B-cell populations were detected in 5 and 6 cases, respectively. Similar to other states of immunodeficiency, disease-related and therapy-induced immunosuppression in T-cell lymphoma may lead to a prominent EBV-associated B-cell lymphoproliferation and to EBV+ B-cell neoplasms.     

Histological and immunohistochemical studies on primary gastrointestinal lymphomas.

To study the characteristics and histogenesis of the malignant lymphomas derived from the gastrointestinal mucosa, histologic and immunohistochemical analyses were performed on a series of 28 malignant lymphomas of the gastrointestinal tract. By cytomorphologic classification, there were two small lymphocytic lymphomas, one small cleaved cell lymphoma, two mixed small cleaved and large cell lymphomas, 17 large cell lymphomas, one small noncleaved cell lymphoma, three immunoblastic lymphomas, and two lymphoblastic lymphomas. This distribution of histologic types was compatible with that of nodal lymphoma. The lymphomas with poor prognostic histology (23 cases) outnumbered those with favorable prognosis (five cases). Three of 28 cases (one in the stomach and two in the small intestine) had cytologic features consistent with centrocytoid cell lymphoma of the mucosa associated lymphoid tissue and were large cell lymphomas. Immunophenotypically, 23 cases expressed B-cell markers (82.1%) and three cases reacted with T-cell markers. Two cases did not react with either T-cell or B-cell markers. True histiocytic lymphomas were not identified. Gastric lymphomas (nine cases) and colorectal lymphomas (three cases) were of B-lymphocyte origin whereas T-cell lymphomas were noted in the small intestine (two cases) and ileocecal region (one case). Three cases of centrocytoid lymphoma were of B-lymphocyte origin. Histologically B-cell lineage lymphomas were evenly distributed on various histologic subtypes but all T-lineage lymphomas belonged to the large cell type. The two cases with undetermined phenotype were lymphoblastic lymphomas histologically. This study showed that the primary GIT lymphomas, mostly of B-cell lineage, were not cytomorphologically distinctive from the nodal lymphomas.(ABSTRACT TRUNCATED AT 250 WORDS)     

Complexities in the diagnosis of large B-cell lymphomas,classic Hodgkin lymphomas and overlapping peripheral T-cell lymphomas simplified: An evidence-based guide

The diagnosis of a large B-cell lymphoma and classic Hodgkin lymphoma (CHL) is often straightforward. However, in select circumstances, these simple diagnoses can be quite complex. In part, diagnostic difficulty may be due to uncertainty in the evaluation of morphologic and immunophenotypic features along a biologic continuum, or alternatively arise from uncertainty in predicting the behavior and outcomes of patients. Here, we systematically discuss and review areas of diagnostic difficulty in the diagnosis of large B-cell lymphomas (LBCL), classic Hodgkin lymphomas (CHL) and peripheral T-cell lymphomas (PTCL). We provide careful data-driven analyses and evidence-based approaches to help guide pathologists and clinicians. We discuss: 1) marginal zone lymphomas with increased large cells versus diffuse large B-cell lymphoma (DLBCL), 2) chronic lymphocytic leukemia with expanded proliferation centers versus diffuse large B-cell lymphoma (DLBCL), 3) chronic lymphocytic leukemia with Hodgkin/Reed-Sternberg-like cells versus CHL arising from chronic lymphocytic leukemia, 4) complex cases of follicular lymphoma versus DLBCL, 5) PTCL with large B-cell proliferations versus PTCL with LBCL, 6) PTCL with Hodgkin/Reed-Sternberg-like cells versus CHL, and finally 7) blastoid/pleomorphic mantle cell lymphoma versus DLBCL. Our evidence and data driven approach may serve as a useful diagnostic guide.     

T-cell lymphomas of the stomach: Morphological and immunological studies characterizing two cases of T-cell lymphoma

Summary Using cytochemical, electron microscopic and immunohistochemical techniques in 20 primary malignant lymphomas of the stomach, we found 18 B-cell and 2 T-cell lymphomas. Primary T-cell lymphoma in the stomach has not been previously reported. The T cells in both cases were reminiscent of T immunoblasts with prominent nucleoli and a basophilic cytoplasm. Case 1 showed a cytological relationship to pleomorphic T-cell lymphoma, large cell type. Case 2 contained in addition some cells not previously described in T-cell lymphomas, resembling immature plasma cells with abundant rough endoplasmic reticulum. Focal positivity to acid phosphatase and dipeptidylaminopeptidase IV suggests the T-cell nature of both lymphomas. In both cases the tumour cells were OKT 11 and OKT 4 positive, and negative for OKT 8. Thus, both cases represent high-grade malignant T-cell lymphomas which correspond phenotypically to T-helper cell lymphoma. Case 2 revealed a further immunohistochemical peculiarity: atypical immunoblasts reacted positively with Ki-1 antibody. Thus, it is a Ki-1 lymphoma of T-cell type.     

CD10 expression in peripheral T-cell lymphomas complicated by a proliferation of large B-cells.

CD10 expression by the neoplastic T cells in angioimmunoblastic T-cell lymphoma was recently described. As cases of peripheral T-cell lymphoma, unspecified, fail to show similar CD10 expression, this feature helps discriminate between these two entities, particularly in cases exhibiting morphologic overlap. Given these findings, we studied CD10 expression in a subtype of peripheral T-cell lymphoma known as peripheral T-cell lymphoma complicated by a proliferation of large B cells and compared it with angioimmunoblastic T-cell lymphoma and angioimmunoblastic T-cell lymphoma with a large B-cell proliferation. A total of 33 cases were identified including peripheral T-cell lymphoma complicated by a proliferation of large B cells (10), angioimmunoblastic T-cell lymphoma (10) and angioimmunoblastic T-cell lymphoma with a large B-cell proliferation (13). Diagnoses were established by hematoxylin and eosin (H&E) stain, immunohistochemistry and/or molecular findings (polymerase chain reaction for T-cell receptor-gamma gene rearrangement). Two of 10 cases of peripheral T-cell lymphoma complicated by a proliferation of large B cells showed aberrant CD10 expression (20%) compared to 9/10 cases of angioimmunoblastic T-cell lymphoma (90%) and 8/13 of angioimmunoblastic T-cell lymphoma with a large B-cell proliferation (62%). One case each of angioimmunoblastic T-cell lymphoma and angioimmunoblastic T-cell lymphoma with a large B-cell proliferation showed a rare, but not unequivocal, CD10+ atypical cell. Four cases of angioimmunoblastic T-cell lymphoma with a large B-cell proliferation were CD10 negative. Of the 2 CD10+ peripheral T-cell lymphoma complicated by a proliferation of large B cells, one had no H&E or IHC features of angioimmunoblastic T-cell lymphoma and showed only a rare positive cell. The second case, a lung biopsy, exhibited diffuse CD10 tumor cell positivity. The predominant staining pattern in the CD10+ cases was characterized by scattered, mostly individual, morphologically neoplastic cells. A rare case showed clusters of positive cells. Our data indicate that only 20% of cases of peripheral T-cell lymphoma complicated by a proliferation of large B cells show CD10 expression by the neoplastic T cells in contrast to angioimmunoblastic T-cell lymphoma and angioimmunoblastic T-cell lymphoma with a large B-cell proliferation which exhibit CD10 staining in 90 and 62% of cases, respectively. This finding does not reach statistical significance with a P-value of 0.57 (Fisher's exact test). As these entities appear to be biologically distinct and may portend different overall survivals, CD10 expression may serve as an additional discriminating criterion.     

Morphologic and immunophenotypic variants of nodal T-cell lymphomas and T-cell lymphoma mimics

Given their relative rarity, one of the primary diagnostic difficulties in nodal T-cell lymphomas is recognizing their range of histologic patterns. This is complicated by the fact that most mature T-cell lymphomas retain some functional characteristics of nonneoplastic T cells, ie, the capacity to secrete cytokines and costimulate immune cell growth, and, thus, are associated with obscuring nonneoplastic immune cells. Sessions 2 and 3 of the Society for Hematopathology/European Association for Haematopathology Workshop focused on these issues and conditions that may simulate T-cell lymphomas. We summarize salient features of presented cases, including the varied patterns seen in angioimmunoblastic T-cell lymphoma (AITL) and other more poorly characterized morphologic and functional nodal T-cell lymphoma subsets. Many cases illustrated the difficulties distinguishing AITL from peripheral T-cell lymphoma, unspecified, when the neoplasms manifest only some AITL features. The usefulness of separately classifying T-cell lymphomas that demonstrate follicular, perifollicular, or T-zone patterns of infiltration; significance of immunophenotypically distinct subsets that express cytotoxic markers or have features of central memory T cells; diagnostic difficulties posed by B-cell proliferations that accompany T-cell lymphomas; and T-cell lymphoma mimics related to genetic disorders, immune dysregulation, and drug reactions are also discussed.     

Histologic patterns of lung infiltration of B-cell, T-cell, and Hodgkin lymphomas

Secondary lung infiltration by lymphomas occurs frequently. To our knowledge, however, no recent studies have attempted to discriminate histologic patterns of lung infiltration in the lymphoma subtypes. We retrospectively evaluated the frequency of lung infiltration and the respective infiltration patterns by lymphomas at autopsy, during an 11-year period. Lymphomas were classified according to the 2001 World Health Organization Classification of hematologic malignancies in B-cell, T-cell, and Hodgkin lymphomas (HLs). In 21,157 autopsies, 414 reports with lymphoma diagnosis were reviewed histologically, and 85 showed lung infiltration (20.5%). We studied 14 HLs, 43 B-cell lymphomas, and 20 T-cell lymphomas. Five infiltration patterns were identified: peribronchial-perivascular, nodular alveolar, interstitial, and pleural. Approximately half of the lymphomas had more than 1 infiltration pattern (mean, 1.7); peribronchial-perivascular and pleural were the most frequent. The frequency of nodular infiltration was larger in HL than in B-cell lymphomas. T-cell lymphomas had a larger frequency of the interstitial infiltration pattern compared with B-cell lymphomas. Recognizing the frequency and patterns of lung infiltration in the light of a more recent classification is certainly useful for physicians dealing with lymphoma diagnostic procedures, such as radiologists and pathologists.     

Frequent expression of CD30 antigen in the primary gastric non-B, non-Hodgkin lymphomas

Most primary gastric lymphomas are of B-cell origin. Fourteen cases of primary gastric non-B, non-Hodgkin lymphomas were studied to evaluate their clinicopathological and immunophenotypic findings. The cases were comprised of 11 men and three women, with a median age of 56.5 years. Most patients underwent surgery either with or without chemotherapy, exhibiting a 5 year survival rate of 57.5%. Morphologically, the neoplastic cells showed various histological features, such as anaplastic large cell lymphoma (ALCL) (n = 3), peripheral T-cell lymphoma, unspecified, large (n = 4), medium-sized (n = 2) and mixed cell (n = 5). Two cases displayed a non-B, non-T cell phenotype, whereas the remaining cases displayed a T-cell phenotype. Six cases were CD4+, while two were CD8+. The neoplastic cells were CD30+ in 10 cases. TIA-1 was positive in six cases. In one case, anaplastic large cell lymphoma kinase (ALK) was identified with immunostaining and chromosomal rearrangement of ALK was detected by fluorescence in situ hybridization (FISH). In conclusion, although the mechanism of CD30 expression is unknown, primary gastric non-B, non-Hodgkin lymphomas tend to express CD30. We consider that some of the cases in the present study may be derived from cytotoxic T cells, similar to systemic and cutaneous ALCL, the majority of which exhibit TIA-1.