Hepatosplenic alphabeta T-cell lymphomas: a report of 14 cases and comparison with hepatosplenic gammadelta T-cell lymphomas

Incidence of TCR and TCL1 gene translocations and isochromosome 7q in peripheral T-cell lymphomas using fluorescence in situ hybridization

Translocations involving the T-cell receptor (TCR) and TCL1 genes occur in T-cell precursor lymphoblastic leukemia/lymphoma and prolymphocytic leukemia; isochromosome 7q has been associated with hepatosplenic T-cell lymphoma. However, the incidence of these abnormalities in peripheral T-cell lymphomas (PTCLs) as a whole has not been well defined. We studied genetic abnormalities in 124 PTCLs seen at the Mayo Clinic, Rochester, MN, between 1987 and 2007. Tissue microarrays were screened using 2-color break-apart fluorescence in situ hybridization probes flanking the TCRalpha (TCRA, 14q11), TCRbeta (TCRB, 7q35), and TCRgamma (TCRG, 7p15) genes and the TCL1 gene (14q32). Isochromosome 7q was analyzed by using a 2-color probe to 7p and 7q32.1. Translocations involved TCRA in 3 (2.9%) of 102 cases and TCRB in 1 (1%) of 88. Isochromosome 7q was detected in 2 cases of extranodal NK/T-cell lymphoma, nasal type, and 2 cases of anaplastic lymphoma kinase-negative anaplastic large cell lymphoma. One of the latter cases also had a translocation of TCRA, and further studies confirmed a novel t(5;14) translocation.

Flow Cytometric Assessment of T-cell Chronic Lymphoproliferative Disorders

Flow cytometry is frequently used in the evaluation of potential T-cell lineage lymphoproliferative disorders. Although flow cytometry is a useful tool, interpretation of the results can be challenging, because T-cells lack an easily analyzed structural element that can provide a surrogate marker of clonality such as immunoglobulin light chains on B-cells. Thus, routine T-cell phenotyping assays in the clinical laboratory require the comprehensive analysis of several T-cell-associated antigens. Although the detection of aberrant patterns of T-cell antigen expression can be helpful in establishing a diagnosis of T-cell malignancy, these patterns are not always disease specific, and some can overlap significantly with T-cell phenotypes observed in reactive conditions. Thus, arriving at an accurate diagnosis requires correlation of the flow cytometry results with the clinical, morphologic, and molecular results. Furthermore, the integration of these varied pieces of information into a cogent diagnosis requires an understanding of T-cell biology. In this review, the use of flow cytometry to identify T-cell lymphoproliferative disorders, particularly in peripheral blood and bone marrow specimens, is discussed, and a brief overview of T-cell biology to aid the reader in understanding the significance of the flow cytometry results is provided.

Hepatosplenic T-cell lymphoma in adolescents and young adults with Crohn's disease: a cautionary tale?

Therapy for the inflammatory bowel diseases increasingly includes the use of immune-modifying and biologic therapies. Recently, in young patients with IBD, an association has been noted between the use of infliximab along with concomitant purine analogues and the development of hepatosplenic T-cell lymphoma (HSTCL)-a rare and all but incurable form of non-Hodgkin's lymphoma. This report briefly reviews the issue of lymphoma and IBD therapy. Additionally, a description of HSTCL and a summary of the known cases of this apparent therapeutic complication are presented. Clinical options in light of this new information are explored.

Hepatosplenic and other gammadelta T-cell lymphomas

The 2005 Society for Hematopathology/European Association for Haematopathology Workshop session 11 was dedicated to hepatosplenic T-cell lymphoma (HSTCL). HSTCL is a rare aggressive type of extranodal lymphoma characterized by hepatosplenomegaly, bone marrow involvement, and peripheral blood cytopenias. HSTCL exhibits a distinctive pattern of infiltration; tumor cells preferentially infiltrate the sinusoids of the splenic red pulp, liver, and bone marrow. The tumor cells have a nonactivated cytotoxic T-cell immunophenotype and frequently carry a recurrent cytogenetic abnormality, isochromosome 7q. Most cases express the gammadelta T-cell receptor, but cases can have an alphabeta phenotype and are considered to be a variant of the disease. Although HSTCL is the prototype peripheral T-cell lymphoma expressing the gammadelta T-cell receptor, non-HSTCL proliferations of gammadelta T cells can involve other extranodal sites, mainly skin and mucosa. These gammadelta T-cell lymphomas display marked heterogeneity in clinical and histologic features. In contrast with HSTCL, non-HSTCL gammadelta T-cell lymphomas frequently have an activated cytotoxic phenotype and most likely are not a single disease entity.

Maligne Lymphome in der Leber

Primary hepatic lymphomas represent rare neoplasms, which are partly observed in association with chronic viral hepatitis, immunosuppression and autoimmune diseases. In contrast, secondary hepatic lymphomas are much more frequent and represent disseminated disease. Lymphomas involving the liver include, with decreasing frequency, diffuse large B-cell lymphoma, small lymphocytic lymphoma, Hodgkin's lymphoma, peripheral T-cell lymphoma, follicular lymphoma and extranodal marginal zone B-cell lymphoma. Many B-cell lymphomas in the liver reveal a characteristic infiltration pattern allowing a rapid and cost-effective diagnosis based on focused immunohistochemical analyses. In contrast, most T-cell lymphomas show a more diverse morphology, which is sometimes difficult to differentiate from a reactive condition. Therefore, additional molecular analyses are frequently necessary. The differential diagnosis includes hepatitis and inflammatory bile duct diseases, undifferentiated carcinoma, inflammatory myofibroblastic tumor as well as histiocytic and dendritic cell neoplasms.

Post-transplant lymphoproliferative disorders following liver transplantation: incidence, risk factors and survival

This study investigates retrospectively the incidence, risk factors and mortality of post-transplant lymphoproliferative disorders (PTLD) in adult orthotopic liver transplant (OLT) recipients. Among 1206 OLT recipients at a single institution, 37 developed a PTLD. The incidence of PTLD was highest during the first 18 months and relatively constant thereafter with cumulative incidence of 1.1% at 18 months and 4.7% at 15 years. The risk of PTLD was approximately 10% to 15% of the risk of death without PTLD. During the first 4 years following OLT, PTLD were predominantly related to EBV, while afterward most PTLD were EBV negative. Significant risk factors for PTLD in OLT recipients were transplantation for acute fulminant hepatitis during the first 18 months following OLT (HR=2.6, p=0.007), and rejection therapy with high-dose steroids (HR=4.5, p=0.049) and OKT3 (HR=3.9, p=0.016) during the previous year. Therapy with high-dose steroids or OKT3 (HR=3.6, p=0.0071) were also significant risk factors for PTLD-associated mortality. OLT recipients remain at risk for PTLD years after transplantation. The strong association of PTLD with rejection therapy and the worse post-PTLD prognosis among recipients of rejection therapy indicate the need to balance the risk of immunosuppression against the risk of PTLD following rejection treatment.

Non-Hodgkin's lymphoma involving the liver: clinical and therapeutic considerations

Primary hepatic non-Hodgkin's lymphoma (NHL) is a rare disease that presents unique diagnostic and therapeutic challenges. Secondary liver involvement by lymphoma is common and can complicate treatment decisions. A review of the published case reports and the few larger series suggests that primary hepatic NHL represents a heterogeneous mixture of disparate diseases rather than a single entity. Presentations vary from the incidental discovery of hepatic abnormalities in an otherwise asymptomatic patient to that of fulminant hepatic failure with rapid progression of encephalopathy to coma and death. The clinical, laboratory, and radiographic characteristics are nonspecific, which means the diagnosis is often not suspected until histopathologic examination of liver tissue. There appears to be a strong association between primary hepatic NHL and the hepatitis C virus. Hepatosplenic T-cell lymphoma has attained its own status as a unique disease, whereas case reports suggest that the spectrum of hepatic lymphoma includes many histologies. Involvement of the liver by lymphoma can compound the difficulty of pursuing aggressive chemotherapy in patients who have a life-threatening illness and impaired metabolism of the most effective drugs. Therapy should be tailored to the individual clinical situation, with consideration of the underlying histology and degree of hepatic insufficiency.

Pathobiology of Peripheral T-cell Lymphomas

Peripheral T-cell lymphomas (PTLs) are uncommon, accounting for fewer than 10% of all non-Hodgkin lymphomas. Success in therapy of the PTLs has lagged behind that of aggressive B-cell lymphomas, and most PTLs have a poor prognosis. The molecular pathogenesis of most PTLs is also poorly understood. In the WHO classification, clinical features, in conjunction with morphological and immunophenotypic criteria, are relied on to define most disease entities.

Functionally, T-cell lymphomas are related to the two major arms of the immune system, the innate and adaptive immune systems. NK cells and T cells of the innate immune system recognize antigen in the absence of MHC antigens and are involved in mucosal immunity. The lymphomas derived from these cells often involve cutaneous and mucosal sites. The expression of cytotoxic molecules in these lymphomas may predispose to apoptosis by tumor cells and normal bystander cells. Hepatosplenic T-cell lymphoma is a systemic disease derived from functionally immature innate effector cells, most often of γδ T-cell origin. In contrast, most nodal T-cell lymphomas belong to the adaptive immune system.

Angioimmunoblastic T-cell lymphoma (AILT) is mostly likely derived from follicular helper T-cells (TFH), a finding that explains many of its pathological and clinical features. Studies of these neoplasms may assist in further unraveling the functional diversity of their normal counterparts.

Hepatosplenic αβ T-cell lymphoma with myelodysplastic syndrome

We describe a patient with hepatosplenic 33 T-cell lymphoma who showed pancytopenia and myelodysplasia. A 35-year-old man was admitted with fever, pancytopenia, and hepatosplenomegaly but with no lymphadenopathy. We also found trilineage myelodysplasia in the bone marrow on his first admission. The patient had high fever and anemia but no evidence of infection and was tentatively treated with prednisolone. This treatment resulted in a transient improvement of the cytopenia and a reduction of spleen size. However, 10 months after the first manifestation, progression of the splenomegaly and fever became apparent, and a splenectomy was performed. The pathologic findings for the spleen showed diffuse and disseminated infiltration of medium- to large-sized T-lymphocytes in the splenic red pulp. These cells were immunohistochemically positive for CD3, CD5, CD7, CD8, CD16, CD56,T-cell receptor 33 (TCR33),T-cell intracellular antigen 1, and granzyme B but were negative for CD4, CD30, CD57, and TCR33. These data suggested a diagnosis of hepatosplenic 33 T-cell lymphoma. A Southern blot analysis revealed gene rearrangement of the TCR 3-chain gene but not the immunoglobulin heavy chain gene in the spleen cells. An in situ hybridization analysis for the Epstein-Barr virus revealed negative results. The patient received 8 courses of combination chemotherapy and achieved a partial remission; however, the dysplastic features of the marrow cells persisted after the partial remission was obtained. Additional treatment with allogeneic bone marrow transplantation resulted in a transient complete remission; however, the patient relapsed 11 months later. Because he had experienced no lymphadenopathy and showed dysplastic features in the bone marrow, the diagnosis was highly dependent on the pathologic findings for the resected spleen.

Immunophenotyping of lymphoproliferative disorders: state of the art

Immunophenotyping was introduced into diagnostic pathology over 30 years ago to assist in the diagnosis and classification of lymphoproliferative disorders. Today the role of immunophenotyping has been expanded beyond this to include the detection of markers of prognosis, determination of disease phenotypes associated with specific chromosomal abnormalities, detection of targets for immunotherapy and to monitor residual disease. Immunoperoxidase detection methods remain the most popular in histopathology, whilst flow cytometry is most commonly applied for haematological samples. The range of monoclonal antibodies available, including those which work in routinely performed tissue specimens, continues to increase. This is in part a result of gene expression studies identifying precise genetic signatures for certain lymphoproliferative disorders and the generation of new protein markers to gene products of upregulated genes. This review summarises the current status and applications of immunophenotyping in the assessment of many of the lymphoid malignancies.

Clinicopathologic and Prognostic Significance of Cytotoxic Molecule Expression in Nodal Peripheral T-Cell Lymphoma, Unspecified

Cytotoxic molecules (CMs) are apoptosis-inducing molecules that are present in azurophilic cytoplasmic granules of T lymphocytes. Expression of TIA-1 and granzyme B was examined for 100 cases of nodal peripheral T-cell lymphoma, unspecified (PTCL-U) to assess clinicopathologic significance of CM. Forty-one were positive for at least one CM. Patients with CM-positive PTCL-U showed younger onset (median, 55 years vs. 64 years, P = 0.01) and less male predominance (male:female ratio, 21:20 vs. 44:15, P = 0.02). CM-positive PTCL-U was significantly associated with several clinical factors to indicate poor prognosis, in comparison with CM-negative PTCL-U, such as poorer performance status (P = 0.006), more frequent B-symptoms (68% vs. 35%, P = 0.002), higher serum lactate dehydrogenase levels (P = 0.003), and more frequent extranodal involvement, particularly bone marrow involvement (33% vs. 9%, P = 0.004). Epstein-Barr virus was mostly found in CM-positive PTCL-U (51% vs. 2%, P < 0.0001). The CM-positive group showed higher distribution of the International Prognostic Index (P = 0.009) and the Prognostic Index for T-cell lymphoma (P = 0.004) scores than CM-negative group. Complete remission rate was 30% for the former but 63% for the latter. Overall survival of CM-positive PTCL-U was significantly lower than that of CM-negative patients (P = 0.004). Multivariate analyses confirmed that CM expression is a significant prognostic factor, independent from other clinical factors or prognostic index scores. These findings suggest that nodal CM-positive PTCL-U show distinct clinicopathologic characteristics among the current category of PTCL-U.

Bone marrow histopathology in peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) account for 10-15% of all lymphoproliferative disorders in the western hemisphere. In PTCL, bone marrow biopsy is performed to establish the diagnosis, rule out other pathology, assess the extent of disease and monitor treatment response. The frequency and histology of bone marrow involvement varies greatly between different clinicopathological entities recognized by the World Health Organisation (WHO) classification, reflecting the differences in the underlying biology. Some lymphomas, such as angioimmunoblastic T-cell lymphoma, show nodular and/or interstitial pattern of infiltration with accompanying reactive changes. Others, including hepatosplenic T-cell lymphoma and large granular lymphocyte leukaemia, are characterized by intrasinusoidal infiltration. In many instances the pathological features are subtle and immunohistochemical and molecular studies are required for the diagnosis. Histological appearances may overlap with a variety of reactive T-cell proliferations and other malignancies. Furthermore PTCL frequently induce secondary changes in the marrow that may obscure the neoplastic infiltrate. The diagnosis often requires critical integration of the information obtained from clinical features, peripheral blood, bone marrow aspirate and biopsy findings. In this article we review the histopathology of bone marrow biopsy in PTCL within the context of the new WHO classification.

A systematic approach to diagnosis of mature T-cell leukemias reveals heterogeneity among WHO categories

The current World Health Organization (WHO) classification of hematopoietic malignancies defines several types of mature T-cell leukemia including T-cell prolymphocytic leukemia (T-PLL), Sezary syndrome (SS), and T-cell large granular lymphocytic (T-LGL) leukemia. These neoplasms can show overlapping features with each other and with T-cell lymphomas involving peripheral blood (PB). We analyzed the spectrum of clinicopatho-logic features in 102 mature T-cell leukemias and compared them to 10 hepatosplenic T-cell lymphomas that involved PB. T-PLL, defined as a T-cell leukemia showing rapidly rising PB lymphocyte counts, was the only tumor type expressing the oncoprotein TCL1 (71% of cases) and could present with relatively low lymphocyte levels or small tumor cell morphology. SS, defined by accompanying erythrodermic skin disease, was frequently associated with peripheral eosinophilia but could also develop high numbers of prolymphocytes, especially late in the disease course. T-LGL leukemia, defined by accompanying cytopenias or autoimmune phenomena (or both), had the best clinical outcome and generally showed the lowest circulating lymphocyte levels with only a few cases developing marked lymphocytosis. Using the dominant clinical or phenotypic feature, we describe here the degree of overlap among currently recognized WHO categories and identify areas where further clarification is needed. Our results indicate that incorporation of additional criteria, such as TCL1 expression status and hematologic parameters, can assist in a more accurate classification. (Blood. 2004;104:328-335)

Clonal T-cell Populations and Increased Risk for Cytotoxic T-cell Lymphomas in B-CLL Patients

Chronic lymphocytic leukemia (CLL) is associated with increased risk of malignancy, but the occurrence of other lymphomas, in particular T-cell lymphomas, is rare. We identified 7 cases of peripheral T-cell malignancy associated with B-cell-derived CLL from the files of two institutions over a 20-year period. The presence of both B and T lymphoproliferative disorders was confirmed in all cases by immunophenotype and in 6 cases by gene rearrangements. Six patients developed peripheral T-cell lymphoma (PTCL), unspecified, during the course of CLL (10-168 months). In all 5 evaluable cases, the cells had a cytotoxic T-cell phenotype; the sixth case was CD56+, but TIA-1 and Granzyme B could not be studied. A seventh patient with CLL developed mycosis fungoides, and an aggressive NK cell leukemia. To investigate possible risk factors for the development of PTCL, we screened 100 unselected peripheral blood samples from newly diagnosed CLL patients by PCR for the presence of clonal T cell populations. We found evidence of clonal T-cell expansion in 8 patients and increased lymphocytes with large granular lymphocyte morphology in 7 of 8 cases. The immunophenotype was assessed by multicolor flow cytometry and in 4 cases the T-cell expansion was composed of either CD3+/CD8+ or CD3+/CD4-/CD8- cells. The cytotoxic nature of the clonal T-cell expansions in the peripheral blood correlates with the cytotoxic nature of the PTCLs, but their role in the subsequent development of T-cell lymphomas is still unclear. PTCL following CLL should be distinguished from typical Richter syndrome, which it can mimic clinically.

Hemophagocytic syndrome and hepatosplenic gammadelta T-cell lymphoma with isochromosome 7q and 8 trisomy

The authors describe a 15-year-old boy with hepatosplenic gammadelta T-cell lymphoma associated with hemophagocytic syndrome (HPS) along with isochromosome 7q and trisomy 8. He presented with prolonged fever, mild anemia, thrombocytopenia, and hepatosplenomegaly. Physical examination, radiography, and ultrasound tomography revealed no lymphoadenopathy. He had elevated levels of serum ferritin, interferon-gamma, soluble interleukin-2 receptor, and interleukin-6. Bone marrow aspirate showed hypercellularity with 50% lymphoblasts and erythrophagocytosis of macrophage. A cytogenetic study of bone marrow revealed an abnormal karyotype, 47,XY,I(7q),+8, in 5/30 cells. Clonal rearrangement of the genes for T-cell receptor gamma and delta chains was elucidated by polymerase chain reaction. He achieved a complete remission after intensive chemotherapy and underwent splenectomy 18 months after diagnosis. Although the patient was clinically in remission, minimal residual disease (MRD) was detected in the removed spleen by polymerase chain reaction. This might mean that this type of lymphoma is refractory, as reported previously, and might indicate that marrow ablative therapy is needed to achieve a cure. The present case illustrates the usefulness of MRD analysis, and MRD studies in this group of disorders may be helpful in the decision of whether to continue a more aggressive therapeutic approach.

Aggressive natural killer-cell leukemia revisited: large granular lymphocyte leukemia of cytotoxic NK cells

Aggressive natural killer-cell leukemia (ANKL) is a rare form of large granular lymphocyte leukemia, which is characterized by a systemic proliferation of NK cells. The clinical features of 22 ANKL cases were analyzed. Hepatomegaly (64%), splenomegaly (55%) and lymphadenopathy (41%) were also frequently observed. Leukemic cells were identified as CD1-, CD2+, surface CD3-, CD4-, CD5-, CD7+, CD8+/-, CD10-, CD11b+/-, CD13-, CD16+, CD19-, CD20-, CD25-, CD33(-), CD34-, CD38+, CD56+, CD122+, HLA-DR+ and TCR-. Two of the 16 cases examined for CD57 were positive and three of the seven cases examined for cytoplasmic CD3. Epstein-Barr virus was detected in the tumor cells of 11 of the 13 cases examined. No common cytogenetic abnormalities were identified and 6q anomaly was detected in only one. Three of 13 patients treated with chemotherapy containing anthracycline/anthraquinone attained complete remission, in contrast to none of the eight who were treated with regimens without anthracycline. Although the overall prognosis was poor with a median survival of 58 days, those who attained remission showed better prognosis (P=0.005). These findings suggest that ANKL is an entity of mature cytotoxic NK-cell neoplasms with distinct phenotype and disease presentations. Intensive treatment for ANKL may result in a better prognosis.

Hepatosplenic lymphoma in a dog

We describe a case of a dog with hepatosplenic lymphoma, a disease characterized by infiltration of the liver, spleen, and bone marrow with gammadelta T cells, absence of peripheral lymphadenopathy, and an aggressive clinical course. Physical examination findings, hematologic and biochemical abnormalities, and clinical course of the disease in this patient were similar to those in humans. Immunophenotyping of liver and spleen aspirates supported an antemortem diagnosis of T-cell lymphoma consistent with hepatosplenic lymphoma. The diagnosis was confirmed postmortem by a combination of routine histopathology, showing a consistent pattern of organ involvement, and immunohistochemistry showing the infiltrating neoplastic lymphocytes to be T cells expressing the gammadelta T-cell receptor. To our knowledge, this is the first reported case of hepatosplenic lymphoma in a dog.

Hepatosplenic T cell lymphoma with no expression of cytotoxic molecules

Hepatosplenic T cell lymphoma is defined as an extranodal and systemic neoplasm derived from cytotoxic T cells. This report describes a postmortem case of T cell lymphoma that showed histological features of hepatosplenic T cell lymphoma but did not express cytotoxic molecules. The patient was a 57 year old man who presented with severe icterus and hepatosplenomegaly, followed by an aggressive clinical course. The liver and spleen were enlarged, weighing 2000 g and 360 g, respectively. Histologically, the liver, spleen, and bone marrow were entirely affected by lymphoma, comprising pleomorphic small and large cells, which displayed sinusoidal infiltration in the liver, diffuse infiltration in the splenic cord, and interstitial/diffuse infiltration with fibrosis in the bone marrow. Lymphoma cells showed positivity for CD3 epsilon, CD8, and CD45RO and clonal rearrangement of the TCRgamma gene by the polymerase chain reaction on paraffin wax embedded sections. However, they were negative for TIA-1 and granzyme B, in addition to betaF1, CD4, and CD56. Few neoplastic cells were stained for Epstein-Barr virus encoded mRNA 1. These findings indicate that this case might represent a variant of hepatosplenic T cell lymphoma despite the absence of cytotoxic molecules.

Classification of cytotoxic T-cell and natural killer cell lymphomas

Mature or peripheral T-cell lymphomas are uncommon, accounting for only 10% to 15% of all non-Hodgkin's lymphomas. The classification of these neoplasms has been controversial. In contrast to B-cell lymphomas, cytologic features have not been useful in defining disease entities, and cytologic grade has not helped predict the clinical course. Similarly, many entities of T-cell or natural killer (NK) cell derivation do not have a specific immunophenotype. Clinical features are of major importance in defining T-cell and NK cell neoplasms, and in some cases the clinical syndrome, may be more important than the precise cell of origin. The majority of cytotoxic T-cell and NK cell lymphomas arise in extranodal sites. The expression of cytotoxic molecules in these lymphomas may predispose to apoptosis by tumor cells and normal bystander cells. Three major categories of extranodal T/NK cell tumors are recognized in the World Health Organization (WHO) classification: extranodal NK/T, nasal-type; enteropathy-type; and subcutaneous panniculitis-like. Epstein Barr virus (EBV) is closely linked to nasal NK/T-cell lymphoma, but shows geographic and racial variations in other subtypes. Tumors resembling the prototype of nasal NK/T-cell lymphoma occur in a variety of extranodal sites, and are referred to as nasal-type. Hepatosplenic T-cell lymphoma is a more systemic disease derived from functionally immature cytotoxic cells, usually gammadelta T-cell origin. Cytotoxic T-cell lymphomas of mature gammadelta T-cell origin most often arise in mucocutaneous sites, and may resemble the prototypes of extranodal T/NK cell lymphoma: nasal, enteropathy-associated, and panniculitis-like. Cytotoxic T/NK cell lymphomas occur with increased frequency in the setting of immune suppression, especially following organ transplantation. The nodal T-cell lymphoma most often exhibiting a cytotoxic immunophenotype is anaplastic large cell lymphoma (ALCL). Primary cutaneous ALCL frequently but not invariably expresses cytotoxic molecules. While the majority of extranodal neoplasms are derived from innate immune effector cells of NK cell and T-cell origin (gammadelta greater than alphabeta), most nodal cytotoxic T-cell lymphomas probably belong to the adaptive immune system. Studies of these neoplasms may assist in unraveling the diversity of their normal counterparts.

Gammadelta T-cell lymphomas

T-cell lymphomas expressing the gammadelta T-cell receptor (TCR) are uncommon, although their frequency may be underestimated. They show a broad clinicopathological spectrum. Besides precursor T-cell lymphoblastic leukemia/lymphoma, various post-thymic gammadelta T-cell neoplasms have been recognized. Among these, hepatosplenic gammadelta T-cell lymphoma constitutes the prototype of T-cell lymphomas expressing the gammadelta TCR and was listed as a provisional entity in the Revised European-American Lymphoma (REAL) classification. The recognition of this lymphoma subtype was further supported by the demonstration that the neoplasm results from a proliferation of nonactivated cytotoxic T cells and is associated with a recurrent cytogenetic abnormality, the isochromosome 7q. More recently, a few cases of hepatosplenic T-cell lymphoma with similar clinicopathologic features and alphabeta phenotype have been described that are thought to belong to the same entity, and the term "hepatosplenic T-cell lymphoma" is preferred in the current World Health Organization (WHO) classification. Most nonhepatosplenic gammadelta T-cell lymphomas occur in skin or in mucosal sites, a location that parallels that of normal gammadelta T cells. In contrast to hepatosplenic gammadelta T-cell lymphomas, they show an important clinical and morphological heterogeneity, have an activated cytotoxic phenotype, and are not believed to constitute a single disease entity.

Hepato-splenic lymphoma: a rare entity mimicking acute hepatitis: A case report

We reported a case of non-Hodgkin's lymphoma where liver involvement was the predominant clinical manifestation. A 27-year old man presented wiht markedly elevated serum aspartate aminotrasferase, alanine aminotransferase and lactate dehydrogenase, reduced prothrombin activity, thrombocytopenic purpura and hepato-splenomegaly without adenopathy. Viral, toxic, autoimmune and metabolic liver diseases were excluded. Bone marrow biopsy showed an intracapillary infiltration of T-lymphocytes with no evidence of lipid storage disease. Because of a progressive spleen enlargement, splenectomy was performed. Histological examination showed lymphomatous intrasinuses invasion of the spleen. Immunohistochemical investigation revealed the T phenotype of the neoplastic cells: CD45+, CD45RO+, CD3+, CD4-, CD8-, TIA1-. About 50% of the lymphoid cells expressed CD56 antigen. The diagnosis of hepatosplenic T cell lymphoma was done. The patient was treated with chemotherapy, which induced a complete remission. Eighteen months later, he had a first relapse with increased aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, thrombocytopenic purpura and blast in the peripheral blood. In spite of autologous bone marrow transplantation, he died twenty months after the diagnosis. Even in the absence of a mass lesion or lymphoadenopathy, hepatosplenic T-cell lymphoma should be considered in the differential diagnosis of a patient whose clinical course is atypical for acute hepatic dysfunction.

Splenic involvement by peripheral T-cell and NK-cell neoplasms

In contrast to B-cell lymphomas, the literature on the splenic pathology of peripheral T-cell and NK-cell lymphomas is limited. Several different patterns of splenic involvement can be observed in peripheral T-cell and NK-cell lymphomas: 1) solitary or multiple fleshy nodule, which is seen predominantly in tumors rich in large cells; 2) diffuse red pulp involvement, which is the commonest pattern; 3) colonization of periarteriolar shealth; and 4) patchy haphazard involvement. However, the miliary small nodule pattern commonly observed in low-grade B-cell lymphomas is practically never seen. In hepatosplenic T-cell lymphoma and T-cell large granular lymphocyte leukemia, the pattern of splenic involvement is rather stereotyped, with diffuse red pulp infiltration and preservation of the sinus/pulp cord architecture, and without formation of nodules. The pattern of involvement is variable from case to case in peripheral T-cell lymphoma unspecified, and there can be associated prominent hemophagocytosis or a masking component of epithelioid granulomas. Aggressive NK cell leukemia and extranodal NK/T cell lymphoma show predominatly red pulp involvement, although the tumor cell density can vary from field to field; blood vessel walls are commonly infiltrated and there can be areas of necrosis.

Non-cytotoxic gamma-delta peripheral T-cell lymphoma affecting the mandibular and parotidal lymph nodes and the skin

In contrast to the majority of alphabeta peripheral T cell lymphomas (PTCL), which usually originate in lymph nodes and do not express NK-associated molecules, most gammadelta PTCL express a cytotoxic phenotype and originate at extranodal sites. We report a case of a patient with a gamma-delta PTCL who presented with large mandibular and parotidal lymphadenopathy and skin lesions. CD3(+)/TCR-Vdelta1 (+) lymphoma cells did not express the cell surface (CD11b, CD11c, CD16, CD56 and CD57) and cytoplasmic granule molecules (Perforin and Granzyme B) that usually characterize the cytotoxic T-cells, a phenotype that fulfils the criteria for diagnosis of a rare non-cytotoxic variant of a gammadelta T-cell lymphoma. "In situ" hybridization for Epstein-Barr virus-encoded RNA and latent membrane protein-1 gave negative results. The disease had an aggressive course and was resistant to chemotherapy and the patient died 4 months after diagnosis.

Hepatosplenic alpha beta T-cell lymphoma: a report of an S100-positive case

Hepatosplenic T-cell lymphoma is an uncommon neoplasm characterized by a lymphoid infiltrate within the sinusoids of the liver, spleen, and bone marrow, without significant nodal involvement. The majority of cases express the gammadelta T-cell receptor and are associated with an isochromosome 7q cytogenetic abnormality. Recently, a small number of cases have been reported that express the alphabeta T-cell receptor. Here, we report our findings of a case of an S100-positive hepatosplenic alphabeta T-cell lymphoma in a 20-year-old woman who presented with pancytopenia and hepatosplenomegaly. The case adds to the growing literature of hepatosplenic alphabeta T-cell lymphomas.

Peripheral T-cell lymphoma

Peripheral (post-thymic) T-cell lymphoma consists of a wide spectrum of disorders with marked differences in biology and behavior. Proper classification is pivotal for evaluating treatment results, and most studies performed a decade ago lump together different disease entities and cannot be interpreted. With improved use of immunophenotyping and molecular methods for these disorders, their exact nature is better defined in the Revised European-American Lymphoma and subsequent World Health Organization (WHO) classifications. The WHO classification of post- thymic T/natural killer (NK)-cell lymphoma consists of 15 entities, including about 30% that are unclassified cases. A wide range in incidence exists between different populations, but it is likely to be lower than previously estimated. Certain entities, like nasal/nasal-type T/NK-cell lymphoma and human T-cell leukemia/lymphoma virus 1, are much more prevalent in certain racial groups and show exquisite viral association. In these entities as a group, prognosis and treatment seem inferior to those of their B-cell counterparts, but treatment must be tailored to the exact pathologic diagnosis and prognostic index. Aggressive combination chemotherapy appears to be curative for certain entities (eg, anaplastic lymphoma kinase-positive), whereas purine analogues may be useful for low-grade entities. The role of autologous and allogeneic stem cell transplantation is still poorly defined. Specific antibody-based therapy is also on the horizon.

Hepatosplenic T-cell lymphoma in a mare

A 21-year-old Dutch crossbred mare was presented with a 1-month history of weight loss and weakness. Clinical evaluation revealed severe anemia and thrombocytopenia with evidence of hepatic disease and muscular damage. Necropsy findings included diaphragmatic rupture with an extensive retroperitoneal hematoma and severe hepatosplenomegaly. Microscopic findings were characterized by hepatic sinusoidal and splenic red pulp infiltration by atypical CD3-positive lymphocytes. No other nodal or extranodal sites were affected. Hepatosplenic lymphoma with a probable T-cell origin was diagnosed based on gross and histologic findings.

Fluorescence in situ hybridization study of chromosome 7 aberrations in hepatosplenic T-cell lymphoma: isochromosome 7q as a common abnormality accumulating in forms with features of cytologic progression

Hepatosplenic gamma delta T-cell lymphoma (HS gamma delta TCL) is a rare and aggressive subtype of peripheral T-cell lymphoma that has been associated cytogenetically with the isochromosome 7q [i(7)(q10)]. The incidence of this aberration and its relevance to pathogenesis of HS gamma delta TCL is still unknown. We investigated the status of chromosome 7 in 12 HSTCL cases, including nine with a typical gamma delta phenotype, one with a so-called T-cell receptor (TCR)-silent phenotype, and two with the variant alpha beta phenotype. We analyzed available fresh and archival material using a dual-color interphase fluorescence in situ hybridization (FISH) approach with 7p and 7q probes. A significant population of cells with predominance of 7q signals was detected in 10 cases (eight gamma delta, one alpha beta, and one TCR silent), and two lymphomas did not show clonal 7p/7q signal imbalances. In four of 10 cases with chromosome 7 aberrations, a hybridization pattern indicative of the presence of one chromosome 7 and one i(7)(q10) was found. In four other cases, the configuration of signals (2 x 7p/3 x 7q) suggested the presence of the i(7)(q10) and additional structural aberrations involving the second chromosome 7. In two cases, including one alpha beta phenotypic variant, a variety of FISH patterns equivalent to two to five copies of i(7)(q10) or numerical and structural aberrations of second chromosome 7 has been detected. These findings support cytogenetic data pointing to a characteristic association of i(7)(q10) with HSTCL, irrespective of the immunophenotype of malignant cells. An increased number of 7q signals was found in three cases with cytologic features of progression, indicating a tendency of HSTCL to multiply the i(7)(q10) chromosome during evolution.

T Cell and NK Cell Lymphoproliferative Disorders

This review covers the diagnosis and management of natural killer and peripheral T-cell lymphomas (PTCL). Problems with PTCL include their rarity, representing usually 10-15% of non-Hodgkin's lymphomas in the Western Hemisphere, morphologic heterogeneity, and lack of immunophenotypic markers for clonality. Additionally, their clinical behavior is variable and may not correlate with morphology.

Dr. Kinney gives a general overview of the diagnosis of PTCL and NK cell neoplasms. Emphasis will be placed on extranodal T cell and natural killer (NK) cell lymphomas such as hepatosplenic lymphoma, subcutaneous panniculitis-like lymphoma and nasal/nasal type T/NK-cell lymphoma. The use of ALK gene regulation in the classification of anaplastic large cell lymphoma is also reviewed.

Dr. Loughran describes current understanding of the pathogenesis of large granular lymphocyte (LGL) leukemia. The discussion focuses on LGL leukemia as an instructive model of dysregulated apoptosis causing both malignant and autoimmune disease. Current management options and mechanisms of therapeutic response are also described.

Dr. Greer addresses whether PTCL should be treated differently from the more common diffuse large B cell lymphomas. He discusses the therapeutic options for anaplastic large cell lymphoma (ALCL), from a conservative approach for primary cutaneous ALCL to combination chemotherapy for the highly chemosensitive ALCL expressing anaplastic lymphoma kinase. He reviews therapy options for the extranodal subtypes of PTCL by drawing from series in adults, pediatrics, dermatology, and the Far East.