Primary central nervous system T-cell lymphoma in aids patients: case report and literature review

According to the published data, most primary central nervous system lymphomas (PCNSLs) are B-cell lymphomas; primary T-cell lymphomas are rare. In a search of the MEDLINE database, we found only 6 cases of primary T-cell PCNSL. Here, we present the case of a 43-year-old man with AIDS, not on highly active antiretroviral therapy, who presented with focal neurologic symptoms and was found on magnetic resonance imaging to have multiple brain lesions. A biopsy showed T-cell lymphoma, and the patient was subsequently treated with whole-brain radiation, to marked clinical response. Reported cases from the literature of primary T-cell PCNSL in AIDS patients are summarized in this review.     

Primary T-cell CNS lymphoma presenting with leptomeningeal spread and neurolymphomatosis

Primary CNS lymphoma (PCNSL), a rare form of non-Hodgkin lymphoma that is confined to the brain, is usually of B-cell origin. Primary leptomeningeal lymphoma, regardless of T or B-cell origin, is an unusual site of presentation. Out of 100 consecutive PCNSL patients that we have followed up in our center during the last 10 years, five had T-cell lymphoma (5%). All presented with leptomeningeal involvement as the sole manifestation and four of them presented with neuronal lymphomatosis. Presenting symptoms included signs of elevated intracranial pressure with 6th nerve palsy; headache and bilateral 3rd nerve palsy; mononeuritis multiplex and unilateral hearing loss; bilateral 7th nerve paralysis and bilateral uveitis. Because neither the CSF nor the MRI were indicative, meningeal or nerve biopsies were required for conclusive diagnosis. Four patients died 10-19 months from disease onset and one patient is alive 36 months following the diagnosis. We conclude that T-cell PCNSL can present as an isolated leptomeningeal involvement which may be associated with neurolymphomatosis affecting cranial and peripheral nerves. These manifestations mimic other neurological conditions such as pseudotumor cerebri or vasculitis. Diagnosis is difficult and, as a result, frequently delayed. This calls for early consideration of meningeal or nerve biopsy whenever CSF findings are inconclusive.     

Growth of Human Lymphoma Cells in SCID Mice

Two EBV-negative human lymphoma cell lines raised in this laboratory and peripheral blood cells of a patient with large cell lymphoma in leukemic phase were injected intravenously or intraperitoneally into C.B.17 SCID mice. One line (OCI-LY18) was derived from the pleural fluid of a patient with a large cell, immunoblastic malignant lymphoma. Cells of this line are of B cell origin and characterized by multiple rearrangements of the JH locus. The second line (OCI-LY17) was grown from the peripheral blood of a patient with a large cell lymphoma of T-cell phenotype which has characteristic rearrangement of the T-cell receptor beta chain. The cells directly obtained from a patient with large cell non-cleaved malignant lymphoma were of B-cell origin.

Animals carrying OCI-LY18 developed large tumor masses within 6-8 weeks of inoculation. The tumors were detected in the intestine, mesentery, retroperitoneum, lymph nodes, spleen, lung and kidney. The masses resembled the primary tumor with respect to histological appearance and immunological phenotype. It was possible to generate secondary cell lines from the tumors found in the inoculated SCID mice. Injection of one of these secondary cell lines into SCID mice resulted in the rapid development of lymphoma and as few as 10 cells were sufficient to establish the disease in the inoculated animals. In contrast cells of OCI-LY17 produced small tumor aggregates that did not appear to progress over time and did not cause death of the animals. The tumors were identified by the same phenotypic profile as that seen in the primary cell line and sections of the patient derived lymph node biopsy.

The sample of peripheral blood cells directly derived from the patient gave rise to tumor nodules in multiple locations. Their morphology and immunological phenotype was consistent with the original disease seen in the patient.     

AIDS-related Central Nervous System Lymphomas

Purpose: To evaluate combined radio-chemotherapy in patients with AIDS-related lymphomatous meningitis (LM) or primary central nervous system lymphoma (PCNSL).Patients and methods: Eighteen men and 2 women with AIDS had cytologically documented LM. Fifteen patients had systemic non-Hodgkin's lymphoma with LM and 5 patients had PCNSL with CSF dissemination. Standardized pre-treatment evaluations included contrast cranial MRI, placement of an intraventricular reservoir, contrast spine MRI, ophthalmologic evaluation and ¹¹¹Indium-DTPA CSF flow studies. Regions of bulky or symptomatic disease were treated with limited-field irradiation. Concurrent systemic chemotherapy was administered in 18 patients. All patients were scheduled to receive intraventricular methotrexate (MTX) according to a concentration×time (C×T) drug schedule. In cytologic or clinical failures, patients were treated with salvage therapy using intraventricular ara-C and in a similar manner, patients were treated with intraventricular thio-TEPA following cytologic relapse or clinical failure intraventricular following intraventricular ara-C.Sixty-seven patients (63 men; 4 women) with PCNSL underwent a standardized pre-treatment evaluation as in patients with LM and were treated according to 3 schedules. In the first group (n=15), comfort care was offered. In the second group (n=45), whole brain radiotherapy was administered. In the third group (n=7), patients were treated with combined radio- and chemotherapy using systemic procarbazine, CCNU and vincristine (PCV-3). The third group was selected based on a Karnofsky performance status 60, no evidence of disseminated PCNSL, a CD4 count 200, no concurrent opportunistic infection and a patient's desire for aggressive therapy.Results: In the LM patient group, 16 patients were evaluable as 4 patients subsequently withdrew consent for treatment. Median time to tumor progression/survival were as follows: not-treated (n=4) 12 days/1 month; treated non-responding (n=6) 30 days/2 months; and treated responding (n=10) 130 days/6 months. In the PCNSL patient group, median range survival were as follows: comfort care (n=15) 1.5/0.5–3 months; whole brain radiotherapy (n=45) 4/1.5–5 months; and combined radio-chemotherapy (n=7) 13/10–18 months.Conclusions: Combined radio- and chemotherapy is appropriate for a small subset of patients with AIDS and either LM or PCNSL. This approach results in meaningful palliation not strikingly dissimilar from that seen in non-AIDS patients.     

Primary CNS lymphoma associated with streptococcal abscess: an autopsy case

This report describes a case of streptococcal abscess in the nodules of a primary central nervous system (CNS) lymphoma. Magnetic resonance imaging (MRI) of the brain revealed multiple lesions with ringlike enhancement over the bilateral frontal, right temporal, and left parietal lobes. On admission, acute brain edema occurred following angiography, which resulted in respiratory arrest. Autopsy findings showed that the ringlike enhanced lesions on MRI were streptococcal abscesses localized in the lymphoma nodules. The lymphoma was classified as non-Hodgkin, diffuse large cells of B-cell lineage. No other lymphoma mass was found extracranially. An immunohistochemical study showed that the lymphoma cells were positive for leukocyte common antigen, Epstein-Barr virus, bax, and bcl-XL, and negative for L-26 and bcl-2. This case demonstrated that an opportunistic streptococcal abscess developed in primary CNS lymphoma in a patient without acquired immunodeficiency syndrome (AIDS), though a few similar cases have been reported in patients with AIDS.     

34例原发性中枢神经系统恶性淋巴瘤临床分析

目的：分析免疫功能正常的中国人原发性中枢神经系统淋巴瘤（PCNSL）的临床资料,探讨PCNSL的临床特征,评价大剂量甲氨蝶呤（HD-MTX）加全脑放疗（WBRT）治疗PCNSL的疗效.方法：回顾性分析34例经病理证实的PCNSL患者的临床资料以及治疗效果,Kaplan-Meier法分析患者生存期.结果：34例PCNSL患者中B细胞淋巴瘤31例（91.2%）,T细胞淋巴瘤3例（8.8%）;所有患者治疗后评价完全缓解率（CR）41.2%,2年生存率60.2%;病理类型和是否接受HD-MTX加放疗是影响PCNSL生存期的主要原因（P＜0.05）.结论：PCNSL以颅内高压为主要表现,B细胞亚型占绝对优势,具有独特的预后因素,HD-MTX联合放疗是PCNSL有效的治疗方法.     

原发性中枢神经系统淋巴瘤临床及预后分析

目的:总结原发性中枢神经系统淋巴瘤(PCNSL)的临床特点、诊治方案及临床疗效.方法:回顾收活的21例PCNSL患者,均为病理确诊的B细胞来源非霍奇金淋巴瘤,其中5例接受单纯放疗,16例接受放化疗.对病理学检查、影像学表现、治疗及预后进行总结分析.结果:PCNSL以中老年人多见,发病急,病程短,病情进展快.临床表现复杂,颅内高压为主要表现之一.CT、MR增强扫描病灶多呈均匀明显强化,可单发或多发.21例患者中位生存时间22个月,1、3和5年生存率分别为76.2％、28.6％和4.76％.放化疗疗效优于单纯放疗,P=0.029.结论:PCNSL临床表现多样,影像学缺乏特异性,极易误诊,确诊需要依靠病理学检查,其最佳治疗方案是三维立体定向穿刺活检加放疗、化疗的联合治疗.PCNSL侵袭性强,生存期短,其预后主要与发病年龄、多灶性和体力状况有关.     

Sequential development of peripheral t-cell lymphoma post immunochemotherapy of diffuse large B cell lymphoma

Reports of sequential occurrence of two or more types of lymphoma are rare, especially when they involve different cell lineages. Herein, we report a rare case of sequential development of peripheral t-cell lymphoma following treatment of diffuse large B cell lymphoma. In a 73-year-old Chinese male patient, diffuse large B-cell lymphoma (DLBCL) was diagnosed in September 2011 based on the result of a tongue biopsy. Afterwards, he received rituximab combined with chemotherapy and local radiotherapy. Though he achieved completed remission, he had a new symptom of one enlarged left inguinal lymph node in November of 2015. A new biopsy was then performed. Immunohistochemistry and polymerase chain reaction (PCR) for gene rearrangements proved monoclonal T-cell lymphoma. We didn't detect EBV infection in either of two biopsies, nor any evidence of immune dysfunction complications. Sequential development of B-cell and T-cell malignancy in this patient maybe an example of treatment-related secondary lymphoma.     

Hepatitis C infection and B-cell non-Hodgkin's lymphoma in British Columbia: A cross-sectional analysis

Objectives: To determine the prevalence of hepatitis C virus (HCV) infection in patients with B-cell non-Hodgkin's lymphoma (NHL) in British Columbia.Design: A cross-sectional analysis.Setting: The British Columbia Cancer Agency (BCCA), a Canadian provincial tertiary oncology referral center.Subjects: Consecutive patients with B-cell NHL registered onto the BCCA lymphoma database in 1996 and part of 1997 and a control group of patients with T-cell NHL registered on the database from 1995 through 1997. Patients with HIV infection were excluded from the analysis. A second control group (n = 1085) consisted of health-care workers tested for HCV infection following a needle-stick injury.Interventions: Stored sera from patients with B-cell NHL (n= 88) and T-cell NHL (n = 37), identified from the database, were tested for the presence of HCV infection with commercially available serologic tests.Main outcome measures: HCV seropositivity in the B-cell lymphoma group compared to the control groups (T-cell NHL and health-care workers).Results: 2.3% of the B-cell NHL group, none of the T-cell NHL group and 1% of the health-care worker control group were positive for HCV infection. These results were not statistically significantly different.Conclusion: Patients in British Columbia with B-cell NHL do not have an increased prevalence of HCV infection. These data suggest that the lymphotrophism of HCV may differ by regional, racial and genotypic variations around the world.     

The value of bone marrow biopsy for staging of patients with primary CNS lymphoma

BackgroundIn patients with presumed primary CNS lymphoma (PCNSL), a systemic manifestation is found only in a small minority. Although bone marrow biopsy (BMB) is recommended for staging, its diagnostic value is unclear.MethodsA retrospective analysis of 392 patients with presumed PCNSL from 3 university hospitals and 33 patients with secondary CNS lymphoma (SCNSL) and initial CNS involvement from a multicenter Germany-wide prospective registry was performed.ResultsA BMB was performed and documented in 320/392 patients with presumed PCNSL; 23 had pathologic results. One harbored the same lymphoma in the brain and bone marrow (BM), 22 showed findings in BM discordant to the histology of brain lymphoma; n = 12 harbored a low-grade lymphoma in the BM, the other showed B-cell proliferation but no proof of lymphoma (n = 5), monoclonal B cells (n = 3), or abnormalities not B-cell-associated (n = 2). In the group of SCNSL with initial CNS manifestation, 32/33 patients underwent BMB; 7 were documented with bone marrow involvement (BMI); 1 had concordant results in the brain and BM with no other systemic manifestation. Six had additional systemic lymphoma manifestations apart from the brain and BM.ConclusionsIn only 2 out of 352 (0.6%) patients with CNS lymphoma (320 presumed PCNSL and 32 SCNSL), BMB had an impact on diagnosis and treatment. While collected in a selected cohort, these findings challenge the value of BMB as part of routine staging in presumed PCNSL.     

Unusual variants of primary central nervous system lymphoma

Rare variants of primary central nervous system lymphoma (PCNSL) include unusual sites of presentation (eg, neurolymphomatosis and primary leptomeningeal lymphoma) and uncommon pathologic entities. Neurolymphomatosis involves peripheral nerves and nerve roots in addition to systemic and central nervous system (CNS) sites. Diagnosis requires a high index of suspicion, and treatment incorporates the principles of therapy for systemic and CNS lymphoma. Primary leptomeningeal lymphoma can present with symptoms of raised intracranial pressure or cranial or spinal polyradiculopathies. Diagnosis can be made by examining cerebrospinal fluid and incorporating immunophenotyping and molecular pathology techniques. Treatment options include irradiation and intrathecal or systemic chemotherapy. The features of PCNSL of T-cell origin and indolent B-cell PCNSL also are discussed.     

原发性中枢神经系统淋巴瘤临床病理及免疫组化研究

[目的]探讨原发性中枢神经系统恶性淋巴瘤(PCNSI。)的病理学特点。[方法]收集10例PCNSL病人的临床资料，并进行病理形态及免疫组化分析。[结果]PCNSL病理形态及免疫组化结果提示均为B细胞性淋巴瘤，其中8例为弥漫性大B细胞淋巴瘤，2例为小淋巴细胞性淋巴瘤。[结论]PCNSL是少见的颅内肿瘤，绝大部分为B细胞性，其亲血管性常形成血管袖套状结构。免疫组化在诊断与鉴别诊断中起着重要作用。     

原发性中枢神经系统淋巴瘤35例临床及预后分析

目的：探讨原发中枢神经系统淋巴瘤（PCNSL）临床特点、诊治方案及临床疗效。方法：总结2001年1月-2008年1月收治的35例PCNSL患者,均经病理证实为B细胞来源非霍奇金淋巴瘤并接受放疗,其中25例放疗后接受化疗。结合文献对原发性中枢神经系统淋巴瘤患者的临床特点、病理学检查、影像学表现、治疗及预后进行回顾性分析。结果：本病以中老年人多见,发病急,病程短,病情进展快。临床表现复杂,颅内高压为主要表现之一。CT、MRI增强扫描病灶多呈均匀明显强化,可单发或多发。35例患者中位生存时间23月,1年生存率74．3％,3年生存率25．7％,5年生存率5．71％。肿瘤全切及局部切除者,生存率未见明显统计学差异（P=0．053）,加化疗疗效优于不加化疗（P=0．012）。结论：PCNSL临床表现多样,影像学缺乏特异性,极易误诊,确诊需要依靠病理学检查,最佳治疗方案是手术加放疗、化疗的联合治疗。PCNSL侵袭性强,生存期短,其预后主要与发病年龄、多灶性、一般状态有关。     

Spinal Manifestation of Malignant Primary (PLB) and Secondary Bone Lymphoma (SLB)

Manifestation of malignant lymphoma in the spine is rare; there have only been a few cases reported in the literature. Due to its rarity, there is no gold standard for the management of patients suffering from spinal lymphoma manifestations. Methods: We retrospectively reviewed the data for 37 patients (14 female, 23 male) with malignant lymphoma in the spine receiving intervention in our center from March 2006 until June 2020. Neurological impairment, pain, diagnostics, and/or surgical instability were the criteria for surgery in this patient cohort. Otherwise, only CT-guided biopsies were conducted. Analysis of the patient cohort was based on the Karnofsky performance status scale (KPSS), location of the lesion, spinal levels involved, spinal instability neoplastic score (SINS), surgical treatment, histopathological workup, adjuvant therapy, and overall survival. The following surgical procedures were performed: posterior stabilization and decompression in nine patients; decompression and/or tumor debulking in 18 patients; a two-staged procedure with dorsal stabilization and vertebral body replacement in four patients; decompression and biopsy in one patient; a two-stage procedure with kyphoplasty and posterior stabilization for one patient; posterior stabilization without decompression for one patient; a vertebroplasty and cement-augmented posterior stabilization for one patient; and a CT-guided biopsy alone for two patients. Twenty-one patients (56.78%) had ≥1 lesion in the thoracic spine, 10 patients (27.03%) had lesions in the lumbar spine, two patients had lesions in the cervicothoracic junction, two patients had lesions in the thoracolumbar junction, one patient had a lesion in the lumbosacral junction, and one patient had a lesion in the sacrum. The diagnoses of the histopathological workup were diffuse large B-cell lymphoma in 23 (62.16%) cases, indolent lymphoma in 11 (29.74%) cases, anaplastic T-cell lymphoma in one case (2.70%), T-cell lymphoma in one case (2.70%), and Burkitt lymphoma in one (2.70%) case. The median overall survival was 7.2 months (range 0.1–266.7 months). Pre- and postoperative KPSS scores were 70% (IQR 60–80%). Manifestation of malignant lymphomas in the spine is rare. Similar to the approach taken for spine metastases, a surgical intervention in cases of neurological impairment or manifest or potential instability is indicated, followed by chemoimmunotherapy and radiotherapy.     

原发性中枢神经系统淋巴瘤7例报道及文献复习

 本文报告原发性中枢神经系统淋巴瘤7例,病理类型均为B细胞型非何杰金氏淋巴瘤(NHL),全部病例采用手术和放射治疗,5例同时接受化疗,平均生存期26.1月,治疗失败主要原因是局部复发。作者结合文献对本病的发生、诊断和治疗进行讨论。     

A New Xenograft Model of Primary Central Nervous System Lymphoma

The management of primary lymphoma of the central nervous system (PCNSL) remains controversial and patients' outcome dismal. In order to investigate new selective therapeutic strategies in a controlled system, a reproducible model of PCNSL in nude rats was developed and characterized. Human B lymphoma cells (BL2) were implanted in the brain frontal area in New Zealand nude rats through a silastic device sealed to the skull. Fifteen and 30 days post-implantation, animals were sacrificed. An autopsy was performed. Representative brain sections were cut and examined for the presence of lymphoma. Immunohistochemistry was performed for proliferation (MIB1-Ki67), a B-cell marker (L26-CD20), a T-cell marker (UCHL1-CD45RO).The analysis of the brains showed tumor growth in 88% of the rats. No mortality was observed. At autopsy no extracerebral, spinal or cerebellar metastasis were found. Microscopically the brain tumors appeared non-encapsulated, highly vascularized, with a characteristic perivascular and diffuse lymphomatous spread in the parenchyma. Immunohistochemistry showed a marked positivity of the tumor cells for L26. Tumor cells were negative for UCHL1. Mean proliferation rate was 30%. The device was well tolerated and caused no local infection. Controlled studies on PCNSL in animal models are lacking. This PCNSL model in nude rats reproduces the histology and location of human CNS lymphoma. Tumor dimensions are within the resolution limits of CT and MRI and therefore suitable for stereotactic therapy. This model provides a tool to test new chemo and radiotherapeutical strategies in a controlled fashion.     

First report on a prospective trial with yttrium-90–labeled ibritumomab tiuxetan (Zevalin) in primary CNS lymphoma

Most patients with primary CNS lymphoma (PCNSL) relapse after primary therapy. Standard salvage treatment has not yet been established in PCNSL. Anti-CD20 immunotherapy has expanded treatment options in systemic B-cell lymphoma; however, its use is limited by reconstitution of the blood–brain barrier after tumor shrinkage. The aim of this phase II trial was to evaluate the therapeutic efficacy, toxicity, and biodistribution of yttrium-90 (⁹⁰Y) ibritumomab tiuxetan in PCNSL. Ten patients with relapsed PCNSL were included in a phase II trial and treated with the ⁹⁰Y-labeled anti-CD20 antibody ibritumomab tiuxetan. Nine patients actually received the planned radioimmunotherapy. In six patients, biodistribution of the antibody was measured by indium-111 (¹¹¹In) ibritumomab tiuxetan whole-body scans and single-photon-emission CT (SPECT) of the brain. All patients were evaluated for toxicity and response at least 4 weeks after therapy. Four patients responded: one patient had a complete response lasting 30+ months, and three patients had short-lived responses of ≤4 weeks. Five patients progressed, and one patient did not receive treatment due to an infection prior to ⁹⁰Y-antibody administration. Target accumulation of the antibody was demonstrated in four of the six patients examined by SPECT imaging with ¹¹¹In ibritumomab tiuxetan. All patients experienced grade 3/4 hematotoxicity but no acute neurotoxicity. Penetration of a therapeutic antibody into PCNSL and significant clinical activity was shown. Because of limited response duration and considerable hematotoxicity, future investigations should focus on a multimodal approach with additional chemotherapy and preferably autologous stem cell support.     

Primary Central Nervous System Lymphoma: A Clinicopathological and Cytomorpholgical Study from A Tertiary Care Centre in Chennai,India

Background: The aim of this study was to analyze the clinicopathological and immunohistochemical featuresof primary central nervous system lymphoma (PCNSL) cases occurring in Indian patients and also study theutility of the crush smear preparation in intraoperative diagnosis. Materials and Methods: The immune status,clinical, radiological details, immunohistochemical profile, histopathological findings and cytological features insmear preparation of 32 cases of PCNSL were analyzed. Patients with systemic NHL and skull-base lymphomaswere excluded. Results: The mean age of our patients was 52 years with a male: female ratio 1:1. A periventricularlocation was found in 62.5% of patients. None of our PCNSL cases were associated with AIDS. All cases exceptone were diffuse large B-cell lymphomas. Intraoperative diagnosis using crush smears allowed correct predictionin 93% of cases. Conclusions: Our study shows that PCNSL is seen predominantly in immunocompetent patientsin India .The age of presentation is relatively young as compared to the West. Our study also stresses the utilityof crush smear preparation in establishing an intraoperative diagnosis.     

原发性乳腺淋巴瘤27例临床分析并文献复习

背景与目的:原发性乳腺淋巴瘤(primary breast lymphoma,PBL)发病率低,预后较差.本研究旨在分析该病例的临床和病理特征,从而探讨PBL的合理治疗模式.方法:收集并回顾性分析1976年到2005年间在中山大学肿瘤防治中心诊断为PBL,并接受治疗的27例患者的临床资料和治疗情况.结果:27例中有26例女性和1例男性患者;年龄12～84岁;90%的患者为Ⅰ E期或ⅡE期.按照WHO 2001淋巴瘤病理分类系统,有22例B细胞性淋巴瘤(17例弥漫大B细胞性淋巴瘤,2例黏膜相关性淋巴瘤,1例边缘区淋巴瘤,2例未能分类),3例外周T细胞性淋巴瘤,2例患者的病理类型未能分类.初始治疗时有20例患者接受了综合治疗,其中8例患者为根治术加术后化疗,12例患者为肿物切除术后加全身化疗,两组的5年生存率分别为23.0%和58.0%(P=0.006);其余有5例患者仅接受全身化疗,2例患者仅接受肿物切除手术.24例患者在初始治疗后取得完全缓解,1例患者部分缓解,2例患者疾病进展.随访时间1个月～10年,中位随访时间38个月.全组患者的5年总生存率和无病生存率分别是47.0%和23.0%;其中20例中高度恶性淋巴瘤患者(17例弥漫大B细胞性淋巴瘤和3例外周T细胞性淋巴瘤)的5年总生存率和无病生存率分别是48.0%和27.0%;随访中有16例复发,部位见于同侧乳腺6例、对侧乳腺4例、中枢神经系统(central nervous system,CNS)3例、骨髓1例和淋巴结侵犯2例.结论:PBL的病理类型以中高度恶性淋巴瘤为主;根治性手术在其治疗中作用有限,肿物切除术加术后化疗和放疗的效果较好.PBL患者易发生CNS复发,在随访中应定期进行颅脑CT或MR检查.     

Application of Immunophenotyping and Heteroduplex Polymerase Chain Reaction (hPARR) for Diagnosis of Canine Lymphomas

Background: Canine malignant lymphoma is classified into B- or T-cell origin, as in the human case. Due to differences in prognosis, a suitable method needs to be developed for lineage identification. Aims: To determine the accuracy of immunophenotypic and molecular information between three methods: immunocytochemistry (ICC), immunohistochemistry (IHC) and heteroduplex polymerase chain reaction for antigen receptor rearrangements (hPARR) in spontaneous canine lymphomas. Materials and Methods: Peripheral blood, fine needle aspiration and tissue biopsies from enlarged peripheral lymph nodes prior to treatment of 28 multicentric lymphoma patients were collected. Cytopathology and histopathology were examined and classified using the updated Kiel and WHO classifications, respectively. Anti-Pax5 and anti-CD3 antibodies as B- and T-cell markers were applied for immunophenotyping by ICC and IHC. Neoplastic lymphocytes from lymph node and white blood cell pellets from peripheral blood were evaluated by hPARR. Results: In this study, low grade B-cell lymphoma accounted for 25% (7/28), high grade B-cell lymphoma for 64.3% (18/28) and high grade T-cell lymphoma for 10.7% (3/28). According to the WHO classification, 50% of all cases were classified as diffuse large B-cell lymphoma. In addition, ICC showed concordant results with IHC; all B-cell lymphomas showed Pax5+/CD3, and all T-cell lymphomas exhibited Pax5-/CD3+. In contrast to hPARR, 12 B-cell lymphomas featured the IgH gene; seven presented the TCRγ gene; five cases showed both IgH and TCRγ genes, and one case were indeterminate. Three T-cell lymphomas showed the TCRγ gene. The percentage agreement between hPARR and ICC/IHC was 60%. Conclusions: Immunophenotyping should not rely on a single method. ICC or IHC with hPARR should be used concurrently for immunophenotypic diagnosis in canine lymphomas.