Diagnosis Of Lymphoid Malignancies Research Articles

Lymphoglandular bodies as useful morphological clue in diagnosis of Lymphoid malignancies- A Case Report

Lymphoglandular bodies, observed as round basophilic cytoplasmic fragments on Giemsa stain, are linked with lymphoid malignancies, aiding in distinguishing lymphomas from other small round cell tumors. This case report underscores the diagnostic significance of Lymphoglandular bodies in Acute lymphoid leukemia diagnosis through bone marrow biopsy. We present a case of a 21-year-old male with chest pain and weakness. The bone marrow biopsy revealed a monomorphic cell population with a high nuclear cytoplasmic ratio, prompting immunomarker analysis that confirmed the presence of blasts as lymphoblasts, leading to the diagnosis of Acute lymphoid leukemia. The identification of Lymphoglandular bodies in bone marrow biopsy facilitated the diagnosis, as peripheral blood examination did not indicate the presence of blasts suggestive of leukemia. Literature on the role of Lymphoglandular bodies in lymphoma diagnosis is limited, with more emphasis on cytological preparations. Lymphoglandular bodies serve as an adjunct in differentiating between lymphoma and non-lymphoma malignancies, being more frequently associated with Malignant lymphoma. The study aim to prove Lymphoglandular bodies as useful morphological clue in diagnosis of Lymphoid malignancies.

IBCL-077: Clinical Characteristics and Outcomes of Indolent B-Cell Lymphoid Malignancies in Carcinogen-Exposed vs Unexposed US Veterans: A Matched Case–Control Study

Context Military personnel and civilians living in theaters of conflict were exposed to environmental carcinogens, such as Agent Orange and Burn Pits, which are associated with increased risk of lymphoid malignancies. There is a need to understand how exposures have impacted disease presentation and outcomes. Objective To determine whether clinical presentations and outcomes of indolent B-cell lymphoid malignancies differ in persons exposed to carcinogens compared to matched unexposed persons. Design Matched case–control study (January 1, 1994 – August 15, 2020). Data abstraction through January 31, 2021. Setting Veteran Affairs Medical Center. Results We studied 217 veterans. Median age at diagnosis was 66 years (range, 32–91), 208 (96%) were male, median duration of time in military service was 3 years (range, 0–23), and median time from enlistment until diagnosis of lymphoid malignancy was 47 years (range, 10–69). First-line management consisted of chemotherapy (n=109), targeted therapy (n=27), other treatments (n=15), untreated (n=60), or unknown (n=6). Fifty-six patients reported carcinogen exposures, and 161 patients did not have documented exposures; both groups were mostly male, 54 (96%) and 152 (95%), respectively. Median age at diagnosis was lower (63 years; range, 33–76) in exposed vs 67 years (range, 32–91) in unexposed patients (p=0.005), and median time from enlistment until diagnosis of lymphoid malignancy was shorter (42 years; range, 13–55) in exposed vs 47 years (range, 10–71) in unexposed patients (p=0.004). Median duration of time in service (3 years; range, 0–28; p=0.11) and median number of therapies (1; range, 0–8) were similar for both groups. Median overall survival in exposed patients was significantly shorter in exposed vs unexposed patients (12 years vs not reached, Log-Rank Test, p Conclusions Veterans who developed indolent B-cell lymphoid malignancies after prior exposure to chemical carcinogens had a younger age at diagnosis, shorter time from enlistment in military service to diagnosis, and shorter survival. Our findings provide the rationale for larger clinical, epidemiological, and mechanistic investigations. Acknowledgments HM is supported by the SOHO Young Investigator Program Award.

Retrospective Analysis of Lymphomas in the Setting of Autoimmune Disease and the Impact of Immunosuppression

Introduction: Post-transplant lymphoproliferative disease (PTLD) encompasses a heterogeneous array of cases of lymphoma/lymphoma-like conditions arising in the setting of immunosuppression (IS) for prior organ or marrow transplant. Such pts face heightened risk of toxicity from exposure to cytotoxic chemotherapy, and may be best treated in the frontline with reduction of IS (RI) and anti-CD20 monoclonal antibody treatment (Trappe, 2012). Autoimmune (AI) disease has been associated with an increased risk of developing lymphoma; however, the relative impact of baseline clinical features, including prior IS, is unknown.Methods: We conducted a multicenter, retrospective analysis of adult pts with pre-existing AI conditions who were diagnosed with lymphoma since 1997. Baseline clinical features at diagnosis of lymphoid malignancy, including International Prognostic Index (IPI) risk factors; underlying AI disease; duration and type of IS; EBV status (by EBER in-situ hybridization); and primary therapy received (RI, rituximab [R] monotherapy, chemotherapy [+/- R]); were collected. Survival analyses were performed using Kaplan-Meier method. We then focused on those who had A) received IS other than corticosteroids (CS) alone; and B) those diagnosed with DLBCL. Those variables found to have significant correlation with OS by univariate analyses (UVA) were used to construct Cox proportional hazards model (multivariate analysis [MVA]) in order to determine which might have the strongest association with OS. Lastly, we sought to evaluate a potential role for RI and/or R as frontline therapy for those with DLBCL.Results: A total of 130 pts were included (Table 1). The most frequent AI disease was rheumatoid arthritis and for all cases, 76% had documented exposure to IS, for a median duration of 4.5 years (range 0.17-57 years) prior to diagnosis of lymphoma. The most common histologic subtype was DLBCL (52%). EBV status was reported for only 34% of pts, but was positive in 68% (25/37), all of whom had received prior exposure to IS beyond CS, and 80% of whom (20/25) were diagnosed with DLBCL. EBV status was infrequently tested in pts not previously exposed to IS (3/31). At a median follow-up of 61 months for the entire cohort, 2-year PFS and OS were 79% and 91%, respectively (Figure 1, Panel A). By UVA, age>60; PS>1; LDH> upper limit of normal (ULN); DLBCL (vs all other histologies); underlying rheumatoid arthritis (RA; vs all other AI diseases); and prior exposure to IS, each correlated with inferior OS (Table 1). By MVA, PS>1 and prior IS maintained significance (p<0.05). If those receiving only CS are grouped with those not previously exposed to IS, the correlation of this factor with OS was strengthened (p 0.008), and by MVA, PS>1 (p 0.002) and prior IS (p 0.010) maintain significance (data not shown).Among 67 pts with DLBCL, median age was 61 (range 26-90), 60% had advanced stage disease, and 32% had IPI of 4 or 5. At a median follow-up of 32 months, the 2-year PFS and OS were 82% and 84%, respectively. There were no differences in frequency of any IPI factors between patients exposed to prior IS (n=53) and those who were naïve to prior IS (n=14). For those not exposed to prior IS, the 2-year OS was 100%, compared to 80% in those who received prior IS (p 0.24); corresponding 2-year PFS were 92% and 79%, respectively (p 0.41). Age>60 and PS>1 were associated with an inferior OS but use of IS was not associated with outcome (Table 2). The 2 year OS for those treated with R plus CHOP(like) chemotherapy, CHOP(like) chemotherapy (without R), R alone (+/- RI), and with RI alone were 92%, 75%, 90%, and 67%, respectively (Figure 1, Panel B; log-rank p value 0.55). Patients who received CHOP-like therapy +/- R, as compared to R and/or RI were more likely to be naïve to IS therapy (15/46 vs 0/22, p = 0.003) and have 2 or more EN sites of disease (15/46 vs 2/22, =0.041). These differences notwithstanding, the 2-year PFS for the two groups were 86% and 74% (p 0.16), and 2-year OS for the two groups were 88% and 82%, respectively (Figure 1, Panel C; p 0.91).Conclusions: Pts with immunosuppression-related lymphoma have high rates of 2-year OS and in DLBCL, IS does not appear to be associated with an inferior outcome. Similar to evolving treatment paradigms in PTLD, rituximab monotherapy and other cytotoxic chemotherapy-free regimens as well as risk-adapted approaches may warrant further evaluation in IS-related DLBCL. [Display omitted] [Display omitted] [Display omitted] DisclosuresPetrich:Seattle Genetics: Consultancy, Honoraria, Research Funding. Barta:Seattle Genetics: Research Funding. Feldman:Celgene: Honoraria, Speakers Bureau; Pharmacyclics/JNJ: Honoraria, Speakers Bureau; Seattle Genetics: Honoraria, Speakers Bureau. Savage:Seattle Genetics: Honoraria, Speakers Bureau; BMS: Honoraria; Infinity: Honoraria; Roche: Other: Institutional research funding.

To Treat or Not to Treat: A Novel Stratification of Myelofibrosis Patients by Likelihood of Response to JAK2 Inhibitors

Objectives: It has been suggested in recent publications that there is a higher incidence of lymphoid malignancies (LM) in patients with myeloproliferative neoplasms (MPN). We report the prevalence of LM in patients with MPN seen at our institution, their clinical characteristics and outcome. Methods: We performed a retrospective chart review of all pts with MPN evaluated at MD Anderson Cancer Center between 1966 and 2013 (N1⁄42647) for evidence of LM. In identified patients with both MPN and LM, we recorded the pathologically-confirmed diagnosis of LM, and analyzed their characteristics, treatment received, and overall outcome, using descriptive statistics. Results: A total of 24 patients with history of both MPN and LM were identified: half were male, 79% white. In 15 patients LM was diagnosed before MPN, with median of 74 months between the two diagnoses (range 2-215), and in 9 LM was diagnosed after MPN, with a median time between the two diagnoses of 97 months (range 2-438). Half of the patients are currently alive, with median follow up of 45 months from initial visit (0-149), 50 months (0-272) from diagnosis of first malignancy. Most common MPN diagnosis among 8 represented subtypes was myelofibrosis (MF) (11 patients, 45%); however, this reflected predominance of MF among our MPN patients (47% of all MPNs). Other types included essential thrombocythemia, polycythemia Vera, mastocytosis, hyper eosinophilic syndrome, Phchronic myeloid leukemia, MPN/myelodysplasic syndrome, and unclassifiable MPN. MPN disease characteristics included: splenomegaly in 42%, abnormal karyotype in 29%, JAK2 mutation in 38%, transformation to acute leukemia in one patient. History of LM did not affect the overall outcome of MPN. LM included 17 lymphoma, 4 myeloma, and 3 Hodgkin’s disease patients that were equally distributed among 8 differentMPN subtypes. Twenty one patients received standard therapy for their type of LM (3unknown) and achieved expectedoverall response; presence orhistory ofMPN did not influence choice of therapy or outcome.Conclusions: In our experience, presence of LM in patients with MPN is very rare event. Presence or history of MPN should not affect the choice of therapy for LM, since it does not have an influence on the outcome.

Detection of malignant B lymphocytes by PCR clonality assay using direct lysis of cerebrospinal fluid and low volume specimens

The diagnosis of lymphoid malignancies is often challenging in paucicellular specimens. PCR may also be limited by insufficient cells for DNA isolation and incomplete coverage of gene rearrangements. This study aims to evaluate a PCR method for IgH clonality using direct cell lysates. PCR amplification used cell lysate from detergent-based lysis and BIOMED-2 primers. CSF specimens were tested for 20 patients with primary CNS lymphoma or systemic lymphoma suspected for CNS involvement. Cytology and flow cytometry analysis was performed in parallel with PCR. Direct lysis produced a better yield than the column-based method for DNA isolation. PCR using lysate showed an efficiency of clonality detection from a minimum of 20 tumor cells. PCR clonality was found in nine of the 20 CSFs, and positive PCR was concordant with both cytology and flow cytometry in seven cases. There were two cases positive for PCR, but indeterminate for flow cytometry because of insufficient cell events. Of the eleven PCR-negative cases, two were considered as false negative, as flow cytometry showed positive for malignant cells. The PCR was also performed successfully with a specimen from the anterior chamber of the eye. PCR clonality with direct cell lysis of CSF is feasible, and it may overcome the limitation of DNA isolation. This PCR method may be particularly useful for small volume and low cell CSF when flow cytometry is inconclusive.

Knochenmarkbiopsie

The rapid technological development in diagnostic pathology, especially of immunohistochemical and molecular techniques, also has a significant impact on diagnostic procedures for the evaluation of bone marrow trephine biopsies. The necessity for optimal morphology, combined with preservation of tissue antigens and nucleic acids on one hand and the wish for short turnaround times on the other hand require careful planning of the workflow for fixation, decalcification and embedding of trephines. Although any kind of bone marrow processing has its advantages and disadvantages, formalin fixation followed by EDTA decalcification can be considered a good compromise, which does not restrict the use of molecular techniques. Although the majority of molecular studies in haematological neoplasms are routinely performed on bone marrow aspirates or peripheral blood cells, there are certain indications, in which molecular studies such as clonality determination or detection of specific mutations need to be performed on the trephine biopsy. Especially, the determination of B- or T-cell clonality for the diagnosis of lymphoid malignancies requires stringent quality controls and knowledge of technical pitfalls. In this review, we discuss technical aspects of bone marrow biopsy processing and the application of diagnostic molecular techniques.

Occupational risk factors associated with Lymphoid Malignancies in Benin City, Nigeria

This study is designed to identify the associated occupations most at risk of developing lymphoid malignancies. The medical records of all lymphoid malignancy cases seen in University of Benin Teaching Hospital between July 2001 and June 2010 were retrieved from medical record library. The patient's bio-data, occupational, social and past medical history and pathologic subtypes were extracted. A total of 252 patients records with diagnosis of lymphoid malignancies were reviewed in this study. Farmers (20.6%) and students (38.9%) form the majority of the cases seen and both showed statistically significant association with risk of LM (p<0.0001) This study revealed that agricultural workers and students in Benin City are at higher risk of developing lymphoid malignancies. Although previous studies have implicated agricultural exposure, the same cannot be said about students. It is therefore recommended that a follow up study should be conducted to ascertain the possible environmental, nutritional, social/lifestyle stressors that put students in Benin City at higher risk of lymphoid malignancies.

Herpes Zoster Is Associated with An Increased Risk of Subsequent Lymphoid Malignancies — A Population-Based Matched-Control Study in Taiwan

Abstract 1599Infectious agents have been shown to contribute to the development of certain lymphoid malignancies. The different distribution of lymphoid malignancies in Asian and Western populations suggests possibly different etiologies in lymphomagenesis in Asian populations. Herpes zoster infection, commonly seen in immunocompromised persons, has been reported to be associated with lymphoid malignancies, but the results are controversial and large-scale studies from Asian populations are lacking. In this study we performed a population-based matched-controlled prospective study on Taiwanese patients using the National Health Insurance Research Database which provided 1,000,000 random subjects from 1996 to 2007. We defined herpes zoster by compatible ICD-9-CM (International Classification of Disease, 9th Revision, Clinical Modification) codes of herpes zoster (053.0–053.9) on at least one service claim for inpatient or outpatient care. The cases were identified by compatible ICD-9-CM codes including Hodgkin’s disease (code 201.0–201.9), non-Hodgkin’s lymphoma (code 200.0–200.8, 202.0–202.9), multiple myeloma (code 203.0–203.1), and lymphoid leukemia (code 204.0–204.9). Patients who had been diagnosed with any lymphoid malignancies or any cancers (code 140.0–199.1) before herpes zoster, and who had been diagnosed with other viral infections (code 045.0–052.9, 054.0–066.9, 071–079.9) and HIV infection (code 042) before the diagnosis of lymphoid malignancies were excluded. We randomly selected 169,983 control subjects (4 for every herpes zoster patient), matched with the study group in terms of age, sex and the year and month of index visit. Of 42,498 patients with herpes zoster prior to the diagnosis of any malignancies, the mean age was 48.92 years (± 20.67 years), with a mild female predominance (52.4%). Patients with herpes zoster infection had a lower monthly income (p < 0.001), and tended to live in urban areas (p < 0.001). Among the patients with herpes zoster, 2.42% subsequently developed cancer, and 0.11% lymphoid malignancy. Among the controls, 2.26% of the patients subsequently developed cancer, and 0.06% lymphoid malignancy. Patients with herpes zoster had a significantly increased risk of developing any cancers (excluding lymphoid malignancies, crude HR: 1.07, 95% CI: 1.01–1.15), and lymphoid malignancies (crude HR: 1.82, 95% CI: 1.29–2.55) compared with the control group. After adjusting for Charlson disease index, income category, and residence using Cox proportional hazard regressions, patients with herpes zoster had an increased risk of developing lymphoid malignancies (adjusted HR: 1.72, 95% CI: 1.22–2.42, p = 0.0019), but did not have an increased risk of developing non-lymphoid malignancies (adjusted HR: 1.00, 95% CI: 0.93–1.07, p = 0.895). These data suggest that preceding herpes zoster infection is an independent risk factor for the subsequent development of lymphoid malignancies in Taiwanese subjects. Further studies are warranted to explore the role of herpes zoster in the pathogenesis. Disclosures:No relevant conflicts of interest to declare.

Importance of Expert Central Review in the Diagnosis of Lymphoid Malignancies in a Regional Cancer Network

The accurate diagnosis of hematologic malignancies remains a challenging area for histopathologists. In 2003, the North Central London Lymphoma network was established to provide a centralized expert review service for general histopathologists based in peripheral nonspecialist hospitals. By studying samples sent for review, we sought to assess the diagnostic and clinical impact of centralized expert review in lymphoma diagnosis. A total of 1,949 patient samples were subject to expert review between 2003 and 2008. Diagnostic discordance rates were identified after expert review, and the impact on patient management was assessed by a hematologic oncology specialist. An overall discordance rate of 27.3% was identified. Among the 10 most commonly referred lymphoid malignancies, the discordance rate varied between 3.6% and 34.1%. A small but significant number of reactive (n = 17) and malignant (n = 5) discordant diagnoses were also identified. Expert central review resulted in a major change to patient management in 2.1% of patients and prevented delays in treatment in 9.3% of patients. During the 6-year study, the discordance rate improved significantly, decreasing from 32% to 13%. Although centralized review incurred additional costs, these were relatively small compared with the costs associated with treatment. This retrospective study demonstrates the importance of expert central review in the accurate diagnosis and timely management of lymphoid malignancies. Furthermore, it shows that where full centralization of services is not viable, a network comprising nonspecialist hospitals linked to a center providing expert review is a practical alternative to full unification of services at a single location and can help prevent local deskilling.

Detection of monoclonal immunoglobulin and T cell receptor gene rearrangements – the UPS and downs of fragment analysis

Immunoglobulin and T cell receptor gene rearrangements can be helpful in identifying monoclonal populations of lymphoid cells in tissue samples. This information can then be used in association with clinical and other laboratory findings to aid in the differential diagnosis of lymphoid malignancies. The gene rearrangements can be detected using polymerase chain reaction (PCR) with analysis by gel electrophoresis. The limited resolution of gel electropho-resis can make interpretation highly subjective and monoclonality in duplicate reactions should be verified by a more accurate method, for example by sizing the PCR products using capillary electrophoresis and fragment analysis software (+/– 1 base pair). This method can provide assurance that monoclonal populations are consistent in replicate samples. However, this approach can provide information about other lesser clonal populations which can complicate interpretation. Our experience indicates that it is important not to over-interpret this extra information. Specific examples will be presented.

Sick Leave due to Depressive Disease: Not a Risk Factor for the Development of Malignant Lymphoma

For unknown reasons the incidence of non-Hodgkin's Lymphomas (NHL) has increased during the last decades. Conditions with impaired immune functions have been associated with an increased risk of malignant lymphomas. Interactions between the central nervous, immune, and endocrine systems have been recently identified, and the potential physiological importance of these interactions is being explored. In this prospective cohort study the potential association between an increasing incidence of depressive disorders and the development of malignant lymphoma is being explored. The participants were part of the Swedish manpower on sick leave between 1988 and 2000 with depressive disease for more than two weeks were followed until a diagnosis of lymphoid malignancy, death, emigration, or end of follow-up period. The final cohort included 87,677 individuals with 373,135 years of follow-up. There were 80 cases of NHL, chronic lymphocytic leukemia (CLL), and Hodgkin lymphoma (HL) with 70 cases expected. The first year of follow-up showed a slightly increased risk of NHL, which most probably can be interpreted as initial symptoms of lymphoma. We conclude that the increase in the incidence of malignant lymphomas observed during the last decades seems not to be associated with a concurrent increase of depressive disorders.

Recent advances in the molecular diagnosis of diffuse large B-cell lymphoma

The field of molecular diagnostics is changing and adapting to new information obtained from genetic, genomic and proteomic profiling of diseases. One of the novel technologies that has made significant impact on the molecular diagnosis of lymphoid malignancies is DNA microarray technology. It has allowed the profiling of the most common types of lymphomas, identifying distinct molecular signatures of these diseases as well as novel subtypes that cannot otherwise be identified by conventional methods. In addition, it has also allowed the construction of molecularly defined prognostic models for various types of lymphomas and to better understand the molecular mechanisms that determine the behavior of the tumor. In this review, recent advances in the molecular diagnosis of diffuse large B-cell lymphoma are highlighted, using examples of how gene expression profiling has been used in disease classification and outcome predictions. The future development of this field and its applications in the clinical arena will also be discussed.

Development of a dual-color fluorescence in situ hybridization probe set on chromosome 6q to improve cytogenetic diagnosis of lymphoid malignancies

Deletions in the long arm of chromosome 6 are one of the most commonly observed chromosome aberrations in lymphoid malignancies and have been identified as an adverse prognostic factor in subsets of leukemia and lymphoma. Although large deletions can readily be detected with conventional banding methods, subtle rearrangements represent a major diagnostic challenge. To identify and follow up 6q abnormalities that are difficult to detect with conventional banding analysis, we have developed a dual-color fluorescence in situ hybridization probe set on 6q21 and 6q27. We have also demonstrated its potential for clinical applications. While applying this new probe set to clinical cytogenetic studies, we identified a unique t(6;14) translocation in a patient with acute lymphoid leukemia. Because the translocation breakpoint on chromosome 6 is located within a common deletion region in patients with lymphoid malignancies, the determination of this translocation breakpoint will facilitate the identification of a candidate tumor suppressor gene in 6q.

The human TCF-1 gene encodes a nuclear DNA-binding protein uniquely expressed in normal and neoplastic T-lineage lymphocytes

The TCF-1 gene encodes a putative transcription factor with affinity for a sequence motif occurring in a number of T-cell enhancers. TCF-1 mRNA was originally found to be expressed in a T cell-specific fashion within a set of human and mouse cell lines. In contrast, expression reportedly occurs in multiple nonlymphoid tissues during murine embryogenesis. We have now raised a monoclonal antibody to document expression and biochemistry of the human TCF-1 protein. As expected, the TCF-1 protein was detectable only in cell lines of T lineage. Its expression was always restricted to the nucleus. Immunohistochemistry on a panel of human tissues revealed that the TCF-1 protein was found exclusively in thymocytes and in CD3+ T cells in peripheral lymphoid tissues. Western blotting yielded a set of bands ranging from 25 kD to 55 kD, resulting from extensive alternative splicing. The TCF-1 protein was detectable in all samples of a set of 22 T-cell malignancies of various stages of maturation, but was absent from a large number of other hematologic neoplasms. These observations imply a T cell-specific function for TCF-1, a notion corroborated by recent observations on Tcf-1 knock-out mice. In addition, these results indicate that nuclear TCF-1 expression can serve as a pan-T-lineage marker in the diagnosis of lymphoid malignancies.

The Human TCF-1 Gene Encodes a Nuclear DNA-Binding Protein Uniquely Expressed in Normal and Neoplastic T-Lineage Lymphocytes

The TCF-1 gene encodes a putative transcription factor with affinity for a sequence motif occurring in a number of T-cell enhancers. TCF-1 mRNA was originally found to be expressed in a T cell-specific fashion within a set of human and mouse cell lines. In contrast, expression reportedly occurs in multiple nonlymphoid tissues during murine embryogenesis. We have now raised a monoclonal antibody to document expression and biochemistry of the human TCF-1 protein. As expected, the TCF-1 protein was detectable only in cell lines of T lineage. Its expression was always restricted to the nucleus. Immunohistochemistry on a panel of human tissues revealed that the TCF-1 protein was found exclusively in thymocytes and in CD3+ T cells in peripheral lymphoid tissues. Western blotting yielded a set of bands ranging from 25 kD to 55 kD, resulting from extensive alternative splicing. The TCF-1 protein was detectable in all samples of a set of 22 T-cell malignancies of various stages of maturation, but was absent from a large number of other hematologic neoplasms. These observations imply a T cell-specific function for TCF-1, a notion corroborated by recent observations on Tcf-1 knock-out mice. In addition, these results indicate that nuclear TCF-1 expression can serve as a pan-T-lineage marker in the diagnosis of lymphoid malignancies.

Acid phosphatase and acid esterase activity in neoplastic and non-neoplastic lymphoid cells. A semiquantitative evaluation related to immunological markers in 112 cases.

Acid phosphatase (AcP) and acid alpha-naphthylacetate esterase (ANAE) were examined in lymphoid cells from 104 patients suffering from various lymphoproliferative disorders and from 8 healthy controls. Enzyme activities were evaluated by means of a scoring system. Scores of AcP and ANAE were higher in normal T cells than non-T cells. In comparison, the activated T cells in infectious mononucleosis showed increased AcP and decreased ANAE reaction. Malignant T lymphoblasts had a distinct granular AcP positivity in contrast to the faint reactivity observed in cALL blasts, whereas ANAE showed negative or weak reaction in both subsets. High scores and distinct staining patterns for both enzymes were found in T CLL and T prolymphocytic leukaemia, clearly different from the weak activities seen in B CLL, B PLL and some B cell lymphomas. The latter, too, could be distinguished by mutual differences in enzyme reactions. High AcP and ANAE scores were also found in hairy cell leukaemia, and the staining patterns together with the tartrate resistance firmly established the diagnosis. Thus, simultaneous determinations of AcP and ANAE can be of great value in the diagnosis of lymphoid malignancies.