AIDS primary central nervous system lymphoma: molecular analysis of the expressed VH genes and possible implications for lymphomagenesis

AIDS-associated primary central nervous system lymphomas are late events that have an extremely poor prognosis. Despite different hypotheses, the brain localization of these B cell lymphomas remains an enigma. To better define the cell origin of the lymphomas and the possible role of the B cell receptor (BCR) in the brain localization and/or in the oncogenic transformation, we analyzed the V region genes of the Ig heavy chain expressed by lymphoma cells in five randomly selected patients. After amplifying the rearranged VHDJH DNA by PCR, cloning, and sequencing of the amplified products, we observed that: 1) of the five lymphomas analyzed, four were clearly monoclonal; 2) there was no preferential use of one peculiar VH family or one peculiar segment of gene; 3) the mutation analysis showed that an Ag-driven process occurred in at least two cases, probably before the oncogenic event; and 4) there was no intraclonal variability, suggesting that the hypermutation mechanism is no longer efficient in these lymphoma B cells. Taken together, our results suggest that distinct Ags could be recognized by the BCR of the lymphoma cells in different patients and that, if the Ags are responsible for the brain localization of these B cells bearing mutated BCR, other factors must be involved in B cell transformations in primary central nervous system lymphoma.     

A 64-year-old woman with progressive gait disturbance and dementia for one year

We report a 64-year-old Japanese woman who died one year after the onset of progressive gait disturbance and dementia. She noted a difficulty in holding a glass and hand tremor in June of 1996 when she was 63 years old. In July of 1996, she tended to lean toward left when she walked. She also noted truncal titubation. In November of 1996, she started to have visual hallucination and delusion in which she said "I see something is flying on the wall.", "Somebody has come into my room", and things like that. She was admitted to our service on November 22, 1996. On admission, she was alert and general physical examination was unremarkable. Neurologic examination revealed disturbance in recent memory. Hasegawa's dementia rating scale was 22/30. She showed vivid visual hallucination with colors in which she saw faces of dwarfs and angels, a space ship, and others. Higher cerebral functions were normal. She showed left oculomotor palsy which was a sequel of an aneurysm and subarachnoid hemorrhage nine years before. Otherwise cranial nerves were unremarkable. She showed ataxic gait, limb ataxia, truncal titubation, and postural hand tremor. She had no weakness and no muscle atrophy. Deep tendon reflexes were within normal limits. Plantar response was flexor. Sensation was intact. Laboratory examination was also unremarkable. Complete survey for occult malignancy was negative. CSF was under a normal pressure and cell count was 1/microliter, total protein 27 mg/dl, and sugar 68 mg/dl. Cranial CT scan was unremarkable. MRI was not obtained because of the presence of an aneurysm clip in the left internal carotid-posterior communication artery junction. She showed progressive deterioration in her mental function. By January 1997, she became unable to stand or walk with marked dementia. Repeated CSF exams and cranial CT scans were unremarkable. She suffered from several episodes of aspiration pneumonia. A trial of three days methylprednisolone pulse therapy was given starting on March 7, 1997, which was of no effect on her neurologic status. On March 28, 1997, she was intubated because of acute respiratory distress syndrome. In April 2, her body temperature rose to 38 degrees C. On April 9, 1997, her blood pressure dropped and resuscitation was unsuccessful. She was pronounced dead on the same day. The patient was discussed in a neurologic CPC and the chief discussant arrived at the conclusion that the patient had primary leptomeningeal lymphoma. Other possibilities entertained among the audience included brain stem encephalitis of unknown type, carcinomatous cerebellar degeneration plus limbic encephalitis, Creutzfeldt-Jakob disease, thalamic degeneration, and progressive multifocal leukoencephalopathy. Post-mortem examination revealed thickening and clouding of the leptomeninges; Gram-positive diplococci were found in the leptomeninges. This meningitis appeared to have been an complication in the terminal stage of her illness. Microscopic examination revealed astrocytosis in the midbrain tegmentum. Cerebral cortices showed only mild astrtocytosis. No cerebellar atrophy was seen and Purkinje cells were retained which excluded paraneoplastic cerebellar degeneration. Neuropathologic diagnosis was bacterial meningitis, however, the presence of brain stem encephalitis prior to the onset of bacterial meningitis could not be excluded. It is interesting to note that the diagnosis of the primary neurologic disease of this patient was not easy even after autopsy. As autopsy permission was obtained only for the brain, it was not clear whether or not this patient had an occult malignancy somewhere in her body, however, there was no evidence to indicate paraneoplastic degeneration of the central nervous system. As the patient did not have meningeal signs until one month before her death, it is difficult to ascribe her entire neurologic problems to her meningitis. Finally, her visual hallucination was vivid and colorful; we thought this might have been     

Intravitreal large-cell lymphoma

Large-cell (non-Hodgkin's) lymphoma may occur in the eye as a cellular infiltrate in the vitreous, uveal tract (choroid), retina, or optic nerve. Lymphomatous involvement may be limited to the eye but also is frequently associated with lesions of the central nervous system. Ocular involvement may precede involvement of the central nervous system by months or, in some cases, years. Ocular large-cell lymphoma is bilateral in approximately 80% of cases but often is asymmetric. The mean age of patients with ocular large-cell lymphoma is 60 years, and women are affected almost twice as often as men. Intravitreal large-cell lymphoma may manifest as an infiltrate of large glassy-gray cells or clusters of cells, and it may mimic uveitis or other inflammatory and infectious conditions of the eye. The diagnosis is based on cytologic and immunocytochemical studies of a vitreous biopsy specimen obtained by aspiration or by vitrectomy through the pars plana. Advances in irradiation of the eyes and the central nervous system, supplemented with corticosteroids and intrathecally and intravenously administered chemotherapeutic agents, have resulted in improvement of the dismal prognosis for patients with large-cell lymphoma.     

Recurrence with histological transformation 40 days after autologous peripheral blood stem cell transplantation (APBSCT) for cutaneous CD30-negative large T cell lymphoma

Localized cutaneous nontender nodules appeared on the back of a 52-year-old Japanese woman. Skin biopsy revealed atypical large T-lymphocytes infiltrating the dermis. CD30 staining was negative in tumor cells. The diagnosis was CD30-negative cutaneous large T cell lymphoma. There was no evidence of peripheral lymphadenopathy or bone marrow involvement. Six cycles of induction chemotherapy were administered and a complete clinical remission (CCR) was attained. Local irradiation was not given. As the clinical course of CD30-negative cutaneous large T cell lymphoma is recurrent and often incurable with conventional chemoradiotherapy, she received high-dose chemotherapy without total body irradiation (TBI) followed by unpurged autologous peripheral blood stem cell transplantation (APBSCT). A relapse in the skin followed 40 days after APBSCT, but tumor cells transformed into a CD30-positive anaplastic large cell lymphoma (ALCL). We question the need for TBI in conditioning and for purged stem cells for APBSCT in patients with high risk cutaneous lymphomas.     

Bulky centroblastic non-Hodgkin's lymphoma of the cranium vault mimicking brain involvement managed with chemotherapy: a case report

BACKGROUND: Patients with central nervous system (CNS) involvement by high grade non-Hodgkin's lymphoma (NHL) have a poor prognosis. The roles of computed tomography, radiotherapy, and intrathecal and systemic chemotherapy still need to be defined. METHODS: A patient with bulky cranial lymphoma mimicking brain involvement is reported. A 62-year-old man was admitted with a huge scalp lump, headache, fatigue, and focal and generalized neurologic symptoms. Computed tomography showed an abnormal mass in the frontoparietal region involving the subcutaneous scalp, osteolytic destruction of the cranial vault, and a bulky mass that was interpreted to be intracranial. A systemic survey also revealed bulky retroperitoneal involvement and focal involvement of the spleen. Biopsy revealed a B-cell NHL of centroblastic type according to the Kiel classification. RESULTS: The patient was treated with a modified combination of cyclophosphamide plus mitoxantrone plus vincristine plus prednisone (CNOP) and intrathecal methotrexate. The patient responded with complete remission, including partial bone restoration of the cranium. At the time of this writing, his relapse free survival lasted 5 years. CONCLUSIONS: The initial interpretation of this case indicated that systemic chemotherapy with modified CNOP plus intrathecal methotrexate would be useful in the management of NHL with CNS involvement. The clinical outcome with rapid neurologic repair and also bone restoration of the cranial vault within 5 years suggests that the lymphoma probably never penetrated the dura and a successful treatment was achieved with combination chemotherapy only.     

Neurologic manifestations of HIV infection

A wide spectrum of central and peripheral nervous system abnormalities may be associated with HIV infection. These disorders may be caused by HIV infection, result as secondary complications related to immunosuppression, or be a neurotoxic effect of therapeutic agents. The range of neurologic disorders includes dementia, focal cerebral mass lesions, myelopathy, peripheral neuropathies, and myopathy. Early diagnosis and therapy is critical, and may result in substantial improvement in patients' quality and quantity of life. This article reviews the approach to differential diagnosis of these neurologic disorders and presents theories of pathogenesis and current approaches to treatment.     

Assessment of cervical lymph node metastasis in esophageal carcinoma using ultrasonography

Cadherins are Ca2+-dependent cell-cell adhesion molecules, and are involved in the formation and maintenance of the organocellular architecture. Using a combination of molecular biologic and biochemical methods, we analyzed cadherins expressed on cultured human malignant lymphoma cell lines (adult T cell lymphomas, human T cell leukemia virus type 1-negative T cell lines, and thymus-derived lymphoma cell lines), and obtained evidence that N-cadherin is the major cadherin expressed on these cells. These cells were found to form cell aggregates in a Ca2+-dependent manner, and more importantly to coaggregate and adhere with cells expressing N-cadherin, suggesting that N-cadherin on lymphoma cells is functionally active. Therefore, N-cadherin expressed on lymphoma cells could underlie the frequent invasion of these cells into the mesenchymal tissue in the skin and the central nervous system.     

A comparison of methods of phenotypic and genotypic fingerprinting of Exophiala dermatitidis isolated from sputum samples of patients with cystic fibrosis

A 77-year-old man was admitted because of massive pericardial effusion and cardiac tumor. Cytological examination of the effusion and histological examination of a subcutaneous tumor in the chest wall revealed diffuse large B cell lymphoma. The immunophenotype of tumor cells was CD5+ CD20+ CD22+ CD38+ HLA-DR+ CD19-. Chromosome analysis revealed complex abnormal karyotypes containing t(8;14) (q24;q32). C-myc gene rearrangement was shown by Southern blotting. Chemotherapy with pirarubicin, cyclophosphamide, vincristin, and prednisolone (THP-COP) was not effective for his lymphoma. He suffered from cardiac tamponade and died at 5 months after diagnosis. Autopsy revealed a large cardiac tumor, extensive epicardial infiltration, tiny tumors in the lung and pancreas, but no lymphadenopathy, the combination of which suggested a primary cardiac lymphoma. Immunohistochemistry for p53 protein showed nuclear staining of more than 50% of the lymphoma cells. In situ hybridization for EBER-1 was negative. Rearrangement of c-myc gene and overexpression of p53 protein are usually observed in Burkitt's lymphoma and some cases of high grade lymphomas including AIDS-associated non-Hodgkin lymphomas. In this case the association of these molecular findings and resistance to chemotherapy is suggested.     

Peculiarity of soleus motor potentials evoked by transcranial magnetic stimulation and electrical stimulation of tibial nerve

Fas (Apo-1/CD95) ligand (FasL) is a cytotoxic molecule used by T lymphocytes and natural killer cells for target-cell killing and by nonmalignant and malignant cells in the suppression of immune responses. In this study, FasL expression in B- and T-cell non-Hodgkin's lymphomas was investigated by paraffin immunohistochemical analysis. FasL expression was found to be weak in nonaggressive lymphomas (chronic lymphocytic leukemia/small lymphocytic lymphoma, lymphoplasmacytoid lymphoma, Grade 1 follicular center cell lymphoma) and mantle cell lymphoma but strong in aggressive B-cell lymphomas (diffuse large B-cell lymphoma, Burkitt's-lymphoma). Precursor B-lymphoblastic lymphomas were more heterogeneous, with expression varying from weak to strong. In T-cell lymphomas (anaplastic large-cell lymphoma; peripheral T-cell lymphoma, unspecified), strong FasL expression was observed. Apparently, FasL expression is not limited to neoplasms derived from T cells or natural killer cells, and it might play a supporting role in the progression of non-Hodgkin's lymphomas.     

Increases in levels of antibody to hepatitis B surface antigen in an immunized population

OBJECTIVE AND IMPORTANCE: Mycosis fungoides is a rare T-cell lymphoma of the skin that can, in one-half to three-quarters of patients suffering from this disease, involve the viscera in late stages of the disease. Although autopsy series performed more than 2 decades ago showed that the incidence of metastatic mycosis fungoides to the central nervous system is approximately one of seven, a total of only several dozen cases have been reported to date. As compared to meningeal involvement, intraparenchymal metastases are even rarer. We describe a biopsy-proven case of intraparenchymal central nervous system mycosis fungoides in a patient with nonprogressive skin involvement and no detectable visceral involvement, and we present a review of the relevant literature. CLINICAL PRESENTATION: A 68-year-old man, 3 years after the diagnosis of his skin disease, developed fatigue, confusion, and frontal lobe signs without the presence of cerebriform cells in the peripheral blood or any other clinical evidence of visceral involvement. Magnetic resonance imaging revealed a diffuse area of increased T2-weighted signal involving the white matter of both cerebral hemispheres as well as a focal area of T2 abnormality along the body of the corpus callosum. The radiological differential diagnosis was either leukodystrophy caused by chemotherapy, progressive multifocal leukoencephalopathy, or glioma with associated white matter changes. INTERVENTION: A stereotactic serial brain biopsy revealed diffuse perivascular infiltrates of atypical lymphocytes, as well as several large cells with cerebriform nuclei consistent with mycosis fungoides. The cells were immunoreactive for LCA, MT1, UCHL1, and CD3. CONCLUSION: We stress the importance of including mycosis fungoides as part of the differential diagnosis for a brain lesion in patients with cutaneous T-cell lymphoma, because treatments do exist, and we conclude that a serial stereotactic biopsy may be necessary to provide a definitive diagnosis.     

An aggressive case of Burkitt's lymphoma with t(8;14) and c-myc rearrangement transformed from CD5+ B-cell lymphoma

We experienced a case of Burkitt's lymphoma showing an unusual surface phenotype, CD5 expression, at an early stage of the disease. Initially, this patient showed massive abdominal para-aortic lymph node swelling which rapidly developed into leukemic change. Based on the clinical course and cytogenetic features of lymphoblasts in the bone marrow, which showed t(8;14) and c-myc gene rearrangement, the patient was diagnosed with Burkitt's lymphoma. Combination chemotherapy induced short-term remission, but central nervous system (CNS) involvement developed, followed by a regrowth of lymphoma cells in the bone marrow. The bone marrow at the end stage showed monotonous expansion of large cells with conspicuous vacuolation in the basophilic cytoplasm. The initial lymphoma cells showed pan-B markers and were CD5 positive but weakly CD10 positive; however, the lymphoma cells obtained from the bone marrow at the terminal stage did not express CD5. The chromosomal t(8;14) was seen, and identical rearrangement of immunoglobulin heavy chain joining gene and c-myc gene were detected by Southern blot analysis in the bone marrow lymphoblasts throughout the clinical course. This case is evidence that remarkable transformation of CD5-positive lymphoblasts to CD5-negative lymphoblasts occurred in an identical clone of Burkitt's lymphoma.     

Bee and wasp venom allergy in Turkey

Astrocytes and derived factors maintain the morphologic, phenotypic, and physiological properties of the blood-brain barrier. Astroglial cells may also modulate endothelial cell properties associated with the entry of inflammatory cells into the brain. The study of mechanisms of lymphocyte migration through the blood-brain barrier is critical to understanding the pathophysiology of autoimmune (multiple sclerosis) and virus-induced central nervous system diseases (HIV-induced dementia). In this context the contribution of astrocyte derived factors in regulating the interactions between inflammatory cells and endothelial cells of the blood-brain barrier was studied. The treatment of endothelial cells derived from brain or peripheral sources (hepatic) with astrocyte conditioned medium resulted in a dose dependent enhancement of adhesion of T cells to endothelium. The antigen specificity of the T cells did not influence the findings. Identical results were obtained with fresh Concanavalin A activated T cells and T cell hybridomas generated using myelin basic protein or chicken ovalbumin as immunogens. Further studies are in progress to define the active components in astrocyte conditioned medium and endothelial cell adhesion molecules that are regulated in order to gain a better understanding of mechanisms of inflammatory cell entry into the central nervous system.     

Pathology of intravascular malignant lymphomatosis

On the basis of six necropsied cases of intravascular malignant lymphomatosis (IML), we elucidated its pathological characteristics. In the brain of IML, multiple softened areas of various size were observed, dominantly in the white matter of the cerebral hemisphere, which showed bilateral distribution with no relation to the supply area of the large vessels and intermingled fresh and old lesions. The spinal cord was one of the most often involved areas in IML, particularly at the lumbosacral segmental level. The origin of the tumor cells, based upon the findings that the tumor cell of all our cases were positive for SL-26, LN1, and LN2, were considered to be B-cell. We speculated that not only the circulatory failure due to the tumor cells which filled the vascular lumen, but also circulatory disturbances due to thrombosis, thickening of the intima and angiitis were significant findings for the necrosis in IML. IML is an important disease as the fourth type of central nervous system involvement due to malignant lymphoma, in addition to primary malignant lymphoma of the brain, meningeal lymphomatosis, compression of the spinal cord caused by extradural metastasis of lymphoma.     

Primary cutaneous large B-cell lymphomas of the legs. A distinct type of cutaneous B-cell lymphoma with an intermediate prognosis. Dutch Cutaneous Lymphoma Working Group

BACKGROUND AND DESIGN: Primary cutaneous follicular center cell lymphomas represent a distinct type of cutaneous B-cell lymphoma, clinically characterized by localized skin lesions on the head or trunk and an excellent prognosis. Histologically similar lymphomas may occur on the legs. The clinical behavior of this group is still undefined, and controversy exists whether these lymphomas should be classified as follicular center cell lymphoma or B-immunoblastic lymphoma. We reviewed the clinical, histologic, and follow-up data of 18 patients with primary cutaneous large B-cell lymphoma of the legs. RESULTS: Primary cutaneous large B-cell lymphoma of the legs generally occurred in elderly patients (median age at diagnosis, 76 years), in particular women (male-female ratio, 7:2), and preferentially affected the lower legs (14 of 18 patients). Radiotherapy and/or systemic polychemotherapy resulted in complete remissions in 16 of 17 patients. Follow-up data demonstrated estimated 2- and 5-year survival rates of 77% and 58%, respectively. Histologic evaluation showed diffuse dermal infiltrates with variable proportions of centroblasts (large noncleaved cells), large centrocytes (large cleaved cells), and B immunoblasts. Seventeen of 18 patients were diagnosed as having primary cutaneous follicular center cell lymphoma; only 1 patient, whose histologic examination showed more than 30% immunoblasts, was diagnosed as having B-immunoblastic lymphoma. CONCLUSIONS: Primary cutaneous large B-cell lymphoma of the legs is a distinct clinicopathologic entity that mainly affects elderly patients and has an intermediate prognosis. Although most cases have a follicular center cell origin, primary cutaneous large B-cell lymphoma is proposed as the most appropriate term for this type of cutaneous lymphoma.     

The safety and efficacy of intrabursal oxycodone and bupivacaine in analgesia after shoulder surgery

We experienced three patients with CD30+ diffuse large cell lymphoma having chromosomal abnormalities. The first patient was an 8-year-old girl with bilateral cervical lymphadenopathy. A biopsy of a cervical lymph node revealed diffuse large cell lymphoma (stage III), positive for CD30 and a chromosomal abnormality, t(2;5). She attained a remission and is now in complete remission 108 months after diagnosis, despite frequent relapses. The second patient was a 13-year-old boy with right axillar and supraclavicular lymph-node adenopathy. A biopsy of a cervical lymph node revealed diffuse large cell lymphoma (stage III), positive for CD30 and a chromosomal abnormality, t(2;5). He attained remission and was in continuous first remission 112 months after diagnosis. The third patient was an 11-year-old boy with fever and bilateral cervical lymph node revealed diffuse large cell lymphoma (stage III), positive for CD30 and chromosomal abnormality without t(2;5). He showed a very aggressive clinical course. Only the patients with Ki-1 lymphoma having t(2;5) survived over 100 months from the diagnosis, despite the advanced stage of the disease. These findings and a review of the literature showed that the presence or absence of t(2;5) may influence the outcome of Ki-1 lymphoma.     

CD4-independent, CCR5-dependent infection of brain capillary endothelial cells by a neurovirulent simian immunodeficiency virus strain

Brain capillary endothelial cells (BCECs) are targets of CD4-independent infection by HIV-1 and simian immunodeficiency virus (SIV) strains in vitro and in vivo. Infection of BCECs may provide a portal of entry for the virus into the central nervous system and could disrupt blood-brain barrier function, contributing to the development of AIDS dementia. We found that rhesus macaque BCECs express chemokine receptors involved in HIV and SIV entry including CCR5, CCR3, CXCR4, and STRL33, but not CCR2b, GPR1, or GPR15. Infection of BCECs by the neurovirulent strain SIV/17E-Fr was completely inhibited by aminooxypentane regulation upon activation, normal T cell expression and secretion in the presence or absence of ligands, but not by eotaxin or antibodies to CD4. We found that the envelope (env) proteins from SIV/17E-Fr and several additional SIV strains mediated cell-cell fusion and virus infection with CD4-negative, CCR5-positive cells. In contrast, fusion with cells expressing the coreceptors STRL33, GPR1, and GPR15 was CD4-dependent. These results show that CCR5 can serve as a primary receptor for SIV in BCECs and suggest a possible CD4-independent mechanism for blood-brain barrier disruption and viral entry into the central nervous system.     

Fibrinolytic treatment with ultra-high streptokinase infusion via the dorsalis pedis vein offers no advantage over systemic infusion via the brachial vein in patients with deep vein thrombosis of the leg

BACKGROUND: Diagnosis of intraparenchymal brain lesions has usually required invasive diagnostic procedures, because too few cells are shed into cerebrospinal fluid to permit cytologic diagnosis. Polymerase chain reaction technology makes it possible to identify cell populations that are present at a much lower frequency than traditional techniques. CASE REPORT: A young woman presented with multiple brain lesions raised the question of primary central nervous system lymphoma. Polymerase chain reaction analysis of cerebrospinal fluid showed evidence of a monoclonal B-cell population heightening suspicion of lymphoma. Brain biopsy showed acute demyelination most consistent with multiple sclerosis. CONCLUSION: Although T-cell restriction has been demonstrated in multiple sclerosis lesions, the finding of a monoclonal B-cell population was unexpected and to our knowledge has not been previously reported. This case emphasizes that monoclonality is not always indicative of a neoplastic process, particularly in the central nervous system.     

Pathogenesis of HIV-1 associated neurodegeneration

A significant number of people infected with the human immunodeficiency virus (HIV) develop neurologic complications. The AIDS dementia complex is frequently accompanied by HIV encephalitis, which is characterized at the neuropathologic level by loss of neuronal subpopulations in the neocortex, limbic system, and basal ganglia in association with synaptic and dendritic damage, astrogliosis, and formation of microglial nodules and multinucleated giant cells. Recent studies have shown that the extent of neurodegeneration in this condition correlates directly with the amount of HIV-1 antigen in the brain. HIV-1 infection of the brain could result in neurodegeneration via neurotoxic effects of viral products (e.g., gp 120, Nef, Tat) and/or via alterations in the expression of host factors. The latter may include increased production of potentially detrimental factors such as cytokines, excitotoxic amino acids, free oxygen radicals, and bioactive lipid mediators as well as interference with the production or action of neurotrophic/protective factors. Derangements of the neuronal calcium homeostasis, lipid peroxidation, and induction of programmed cell death (apoptosis) may all play a role as final common pathogenetic pathways in HIV-1-induced neurodegeneration. Recent studies in transgenic mice (over)expressing HIV- or host-derived proteins in their central nervous system indicate that distinct neuronal populations may differ in their susceptibility to specific pathogenic factors. For example, glutamate-receptor-bearing pyramidal neurons were particularly susceptible to neurodegeneration promoted by HIV-1 products, whereas interneurons were more sensitive to the neurotoxic effects mediated by cytokines. For the design of effective treatments for the HIV-1-associated cognitive/motor complex, it will be important to determine whether the neurologic deficits in this entity result from global neuronal dysfunction or relate more specifically to the impairment of distinct neuronal subpopulations. It will also be critical to examine diverse in vitro and in vivo models to help decide which of the many pathogenetic processes that may be at work in this complex disease constitute the most promising therapeutic targets.     

Expression of perforin in nasal lymphoma. Additional evidence of its natural killer cell derivation

Eight patients with nasal lymphoma in whom fresh-frozen tissues were available were studied to elucidate the nature of the lymphoma cells. Two cases were diagnosed as diffuse, large cell lymphoma, and the remaining six cases as diffuse, mixed cell types. Immunohistochemical studies revealed that all of the cases were positive for perforin, which is a specific marker for cytotoxic T or natural killer (NK) cells. As all of the cases were CD8 negative, the perforin-positive finding further confirmed the concept that nasal lymphoma is a distinct neoplastic entity derived from NK or NK-related cells. Light microscopic immunohistochemical studies revealed that these nasal lymphoma cases could be classified into Leu19(CD56)+Leu4(CD3)+ (two cases) and Leu19(CD56)+Leu4(CD3)- (six cases) types according to the phenotypes of the proliferating cells. However, simultaneous staining for perforin and Leu4 (CD3) using immunoelectron microscopy on the Leu19+Leu4+ cases showed that the perforin-positive cells were different from the Leu4-positive cells. This finding suggests that the Leu4-positive cells are not neoplastic NK cells but reactive T cells. Six cases were positive for EBER-1 by in situ hybridization analysis. This finding reconfirms the previous studies that Epstein-Barr virus plays a significant role in the pathogenesis of nasal lymphoma.