Acute lymphoblastic leukemia in adolescents between 10 and 19 years of age in Denmark--secondary publication.

INTRODUCTION: Data seem to indicate that young adults with acute lymphoblastic leukemia (ALL) have a better survival when treated with pediatric protocols compared with adult ALL protocols. The purpose of the study was to report the clinical characteristics and outcome of all children and young adults 10-19 years of age diagnosed with ALL in Denmark between 1992 and 2001. MATERIAL: The study includes 99 patients 10-19 years of age with ALL in Denmark during a ten year period found in the complete NOPHO (Nordic Society of Pediatric Hematology and Oncology) registry and through the Danish Cancer Registry and local pathology databases. Data were retrieved by reviewing medical charts of the patients. A total of 61 children (10-14 years) treated on pediatric protocols and 38 young adults (15-19 years) were diagnosed with ALL. Data were reported as of January 1st 2005. RESULTS: There were no difference with respect to the distribution of T-ALL, CNS-leukemia, total white blood count and high risk chromosomal abnormalities between the two groups. There was a statistical significant lower event free survival (p<0.01) and lower overall survival (p<0.01) in young adults compared with 10-14 year-old children (0.38 vs 0.60 and 0.47 vs 0.67). There were more transplant-related deaths in the young adults. Higher treatment intensity in children may be an additional explanatory factor. Children received more prednisone, vincristine and high-dose methotrexate than young adults. CONCLUSION: Young adult patients with ALL might benefit from therapy with pediatric NOPHO ALL protocols.

Immunoelectron microscopy studies on the modulation of common acute lymphoblastic leukemia antigen (CALLA) on NALM-6 cells: delineation of intracellular transport.

Even though much is known about the presence of the common acute lymphoblastic leukemia antigen (CALLA) with respect to its distribution in hematopoietic and non-hematopoietic tissues, its functional role in lymphoid cells is as yet unknown. Given the fact that CALLA is completely modulated on the surface of lymphoid cells, we have employed pre-embedding immunogold techniques at electron-microscopical level and demonstrated that J5 monoclonal antibody (MoAb)-mediated modulation of CALLA expression on the lymphoblastic cell line NALM-6 is a specific, rapid process, closely resembling receptor-mediated endocytosis. Furthermore, it was found that CALLA was internalized through plasmalemmal pits and cytoplasmic vesicles and processed intracellularly in multivesicular bodies and secondary lysosomes. In contrast, HLA-DR antigen remained at the cell surface upon contact with specific MoAb. These data suggest that CALLA might be a receptor for a hitherto unknown signal molecule.

Aclarubicin plus cytosine arabinoside versus daunorubicin plus cytosine arabinoside in previously untreated patients with acute myeloid leukemia: a Danish national phase III trial. The Danish Society of Hematology Study Group on AML, Denmark.

A regimen of aclarubicin (ACR) of 75 mg/m2 daily for 3 days plus a continuous intravenous infusion of cytosine arabinoside (ara-C) of 100 mg/m2 per day for 7 days was compared with daunorubicin (DNR) 45 mg/m2/day for 3 days plus ara-C for 7 days as first-line chemotherapy of de novo acute myeloid leukemia (AML) in a randomized, nationwide Danish study. A total of 180 patients aged between 17 and 65 years were entered onto the protocol. Patients who achieved complete remission (CR) were given five courses of intensive consolidation therapy consisting of two courses of high dose ara-C, two courses of amsacrine plus etoposide, and one course of DNR plus ara-C. Of 174 evaluable patients, 99 achieved CR. The rate of CR was significantly higher on ACR plus ara-C than on DNR plus ara-C [66% versus 50% (p = 0.043)] and decreased significantly with increasing age. The hematological toxicity was identical for the two regimens. A total of 83 patients entered consolidation therapy. At 4 years, 37% of patients with CR following ACR were still in remission compared with 33% following DNR (p = 0.48), and the total survival at 4 years was 29% versus 20% (p = 0.26). The duration of remission and total survival both decreased with increasing age. ACR plus ara-C seem at least as good or better than DNR plus ara-C as first-line chemotherapy of AML.

Long-term survival and development of secondary malignancies in patients with acute myeloid leukemia treated with aclarubicin or daunorubicin plus cytosine arabinoside followed by intensive consolidation chemotherapy in a Danish national phase III trial. Danish Society of Haematology Study Group on AML.

In 1991 we reported the results from a prospective randomised phase 3 trial comparing 7 days continuous infusion of cytosine arabinoside (ara-C) combined with either daunorubicin (DNR) or aclarubicin (ACR) as direct i.v. injection for 3 days as induction chemotherapy (CT) for patients with de novo acute myeloid leukemia (AML) followed by early intensive consolidation CT with two alternating cycles of high-dose ara-C and two cycles of amsacrine plus etoposide, and finally 3 days of daunomycin plus 7 days of ara-C as administered for induction of remission. A total of 174 patients with de novo AML in the age group 17-65 years were included. The patients have now been followed till death or for at least 7 years, and an evaluation of the long-term survival and the risk of developing secondary neoplasms has been made. The overall survival rate 5-years after diagnosis was 23%, and after 10 years 19%. No difference was found between the two treatment regimens in overall survival or disease-free survival (DFS). For the subgroup of 99 patients who achieved complete remission after one or two induction courses, 5- and 10-year survival rates were 35% and 31% respectively, with the highest survival rates in the age group 17-39 years (57% at 5 years) as compared with 27% in patients aged 40-60 years (P= 0.007). Seven secondary neoplasms were diagnosed simultaneously with or after the diagnosis of AML indicating a standardized incidence ratio (SIR) of 3.41, (95% CI: 1.60-7.26). In three cases the secondary neoplasms were diagnosed simultaneously with the AML diagnosis and were for that reason completely unrelated to the chemotherapy administered for AML, as the psammomatous meningeoma diagnosed after only 8 months. The remaining three neoplasms which developed subsequently did not significantly exceed the expected number, with a SIR = 1.46 (0.47-4.57). Thus, no increased risk of solid tumors causally related to the intensive chemotherapy for de novo AML was observed. However, a generally increased risk of solid tumors in patients diagnosed simultaneously with the AML diagnosis seems likely. Over 20% of the patients were alive and in complete remission 5 years after the AML diagnosis, and they have a high probability of surviving the next 5-year period.

Modulation and intracellular transport of CD20 and CD21 antigens induced by B1 and B2 monoclonal antibodies in RAJI and JOK-1 cells--an immunofluorescence and immunoelectron microscopy study.

By fluorescence microscopy (FM), flow cytometry (FCM) and immunoelectron microscopy (IEM) we have shown that B1 and B2 monoclonal antibodies (MoAbs) were able to induce modulation of CD20 and CD21 in RAJI and JOK-1 cell lines. Redistribution and internalization of both antigens (Ags) after binding with MoAbs was readily demonstrated by FM, and by IEM CD20 and CD21 were found to be processed by the pathway of receptor-mediated endocytosis. The rate of intracellular transport varied: CD21 > CD20 and RAJI > JOK-1. Approximately 65 and 55% of CD20 and 60 and 45% of CD21 were cleared from the surface of RAJI and JOK-1 cells, respectively (FCM and IEM). These values, however, clearly exceeded those corresponding to internalization (11, 9, 24 and 16%) indicating shedding of Ag-MoAb complexes. No evidence of recycling was found. The present data support the hypothesis that the kinetics of modulation vary from one Ag to another and probably also reflect the stage of differentiation of the malignant B-cells. The results are discussed in the context of the possible usefulness of B1 and B2 MoAbs in the therapy of B-cell malignancies.

Extreme hypodiploidy in a case of myelomonocytic crisis of chronic myelogenous leukemia.

Two cytogenetically distinct populations of marrow cells were observed in a 28-year-old woman who developed a fulminant blastic crisis (BC) of chronic myelogenous leukemia (CML) after only 1 year in the chronic phase: one population with 35-36 chromosomes, the other showing 66-72 chromosomes. Cytochemical investigation demonstrated a myelomonocytic type of BC. Chromosome banding and correlation analysis of the mean karyotypes of the two populations showed that a close relationship existed between them, indicating that one population had developed from the other. The cytogenetic evidence suggests but does not prove that the cells with triploid chromosome numbers developed from the extremely hypodiploid population by duplication of the chromosome complement. The extreme cytogenetic diversity of both populations indicates that each was undergoing further cytogenetic evolution.

Incidence, presenting features and prognosis of low-grade B-cell non-Hodgkin's lymphomas. Population-based data from a Danish lymphoma registry.

During the period January 1983 to January 1988 1597 newly diagnosed cases of non-Hodgkin's lymphoma (NHL) were included in a Western Danish population-based NHL registry. Of these, 31% (N = 496) were low-grade NHL (LG-NHL) consisting of (Kiel): 9% lymphocytic (LY), 27% lymphoplasmacytic/-cytoid (IC), 53% follicular centroblastic/-centrocytic (CB/CCf) and 11% unclassifiable low-grade. LG-NHL (age range: 26-94 yrs, median: 64 yrs; M/F ratio: 0.8) had an age-standardised incidence rate (IR) of 2.7/10(5)/yr. Age-specific IR's showed an age-related exponential rise in all subtypes except for CB/CCf. Compared with the intermediate (IG)- and high-grade (HG) group, LG-NHL had more female cases (M/F ratio: 0.79 vs. 1.2; p = 0.0002), a higher frequency of stage III-IV disease (66% vs. 53%; p < 0.00005) and of bone marrow involvement (39% vs. 19%; p < 0.00005). A later revision of all IC cases (N = 132) distinguished 79 non-polymorphic (ICnp) from 25 polymorphic (ICp) cases; 28 cases were differently classified. In 34 LG-NHL patients histologic transformation was verified: CB/CCf to CB diffuse (22 pts) and LY to immunoblastic or CB type (6 pts). The 7-yr survival for LG-NHL was 63% (IG: 48%, HG: 38%; p < 0.00005). A Cox-regression analysis identified the following adverse prognostic factors for survival in LG-NHL: age > 50 with a relative risk (RR) of 3.2, hepatic involvement (RR = 2.1), elevated s-LDH (RR = 1.9), B-symptoms (RR = 1.8) and IC histology (ICnp+ICp) (RR = 1.7).(ABSTRACT TRUNCATED AT 250 WORDS)

Clinicopathological features, survival and prognostic factors of primary central nervous system lymphomas: trends in incidence of primary central nervous system lymphomas and primary malignant brain tumors in a well-defined geographical area. Population-based data from the Danish Lymphoma Registry, LYFO, and the Danish Cancer Registry.

It has been claimed that Primary Central Nervous System Lymphomas (PCNSL), a rare neoplasm accounting for only a small fraction of malignant brain tumors and extranodal non-Hodgkin lymphomas (NHL), occur with increasing frequency in immunologically normal as well as in immunocompromised individuals. In an attempt to characterize the clinicopathological features, outcome and prognostic factors of PCNSL we here report our experience in a large unselected series of patients from a well-defined region. In addition, we present data on trends in incidence of PCNSL and primary malignant brain tumors in a well-defined geographical area. In a Danish population-based NHL registry (LYFO) representing a population of 2.7 million all new cases of NHL were registered during the approximate 11-year period from 1st January 1983 to 31st May 1994. Incidence data of primary malignant tumors of the brain and central nervous system in western Denmark for the period 1971-1990 have been obtained from the Danish Cancer Registry. During the approximate 11-year period 3124 new cases of NHL were registered. Of these, 1152 (37%) were extranodal and 48 were non-AIDS related PCNSL accounting for 4.2% of extranodal NHL and 1.5% of all NHL, respectively. The average annual incidence rate of non-AIDS related PCNSL during the period was 1.56 cases per million population (age range: 15-85 yrs, median: 62 yrs, M/F ratio: 1). In a 23-year period there was no trend towards an increasing incidence of non-AIDS related PCNSL in a well-defined population. PCNSL accounted for 1.7% of all primary malignant brain tumors. Incidence of primary malignant brain tumors was stable, except for age ranges over 70 years. However, diagnostic artifacts might be responsible for this apparent increase. Histologically, 85% were high grade. Using the Kiel classification centroblastic diffuse (60%) and immunoblastic lymphoma (13%) were the most common subtypes. Forty-three patients had B-cell lymphoma and no T-cell lymphoma was detected. Forty-seven cases were diagnosed pre mortem. Treatment included surgical resection (26 patients), whole brain irradiation (WBRT) (43 patients) and chemotherapy (28 patients). Median survival for those receiving either WBRT or WBRT and chemotherapy was 8 months and 20 months, respectively (p = 0.78). Overall survival was 53%, 38% and 26% at 1, 2 and 5 years. Cox-regression analysis identified only one factor having independent impact on survival in PCNSL: performances score > or = 2 (p < 0.001, RR = 5.8).

Outcome for patients with leukemia, multiple myeloma and lymphoma who relapse after high dose therapy and autologous stem cell support.

Relapses after autologous transplantation are a serious clinical problem in patients with haematological diseases. The decision making for handling of such patients is difficult and the aim of this retrospective analysis of posttransplant relapses was 1) to obtain information of practical importance for the management of future relapses and 2) to evaluate the basis for clinical phase I-II trials of salvage therapy combined with biological modifiers. Included in the study were 283 patients with acute leukemia, multiple myeloma and malignant lymphoma who relapsed after autologous transplantations during a five year period from 1989 to 1994. Chemo- and radiotherapy was given to 229 patients after relapse or due to progressive disease and the response evaluated after 90 days. Fifty four patients (24%) obtained a complete remission and 44 patients (19%) partial responses. The overall median survival from relapse was 5 months. In the group given salvage treatment the median survival was 7 months and in the 54 patients who obtained remission the median survival was 15 months. So far 6 of 14 patients in continuous complete remission have a remission time after relapse longer than the time in remission after transplantation. Survival after relapse depended upon the time from transplantation to relapse, primary disease and if salvage therapy was given. In conclusion posttransplant relapses can be treated but the strategy has to be evaluated in future clinical trials.

[Primary cerebral non-Hodgkin's lymphomas and primary malignant brain tumors in a well-defined geographical area. Population-based data from the registry of non-Hodgkin's lymphoma in western Denmark, LYFO and the cancer registry, Kraeftens Bekaempelse]. / Primaere cerebrale non-Hodgkins lymfomer og primaere maligne hjernetumorer i et veldefineret geografisk område. Populationsbaserede data fra det vestdanske non-Hodgkins lymfom-register, LYFO, og Cancerregisteret, Kraeftens Bekaempelse.

In a Danish population-based non-Hodgkin's lymphoma (NHL) registry (LYFO) representing a population of 2.7 million all new cases of NHL were registered from 1st January 1983 to 31st May 1994. Incidence data of primary malignant tumours of the brain and central nervous system in western Denmark for the period 1971-1990 have been obtained from the Danish Cancer Registry. During the approximate 11-year period 3124 new cases of NHL were registered. Of these, 1152 (37%) were extranodal and 48 were non-AIDS related primary central nervous system lymphomas (PCNSL) accounting for 4.2% of extranodal NHL and 1.5% of all NHL, respectively. The average annual incidence rate of non-AIDS related PCNSL during the period was 1.56 cases per million population (age range: 15-85 yrs, median: 62 yrs, M/F ratio: 1). In a 23-year period there was no trend towards an increasing incidence of non-AIDS related PCNSL in a well-defined population. PCNSL accounted for 1.7% of all primary malignant brain tumours. Incidence of primary malignant brain tumours was stable, except for age ranges over 70 years. Histologically, 85% were high grade, centroblastic diffuse (60%) and immunoblastic lymphoma (13%) (Kiel classification). No T-cell lymphomas were detected. Treatment included surgical resection, whole brain irradiation (WBRT) and chemotherapy. Median survival for those receiving either WBRT or WBRT and chemotherapy was eight months and 20 months, respectively (p = 0.78). Overall survival was 53%, 38% and 26% at one, two and five years. Cox-regression analysis identified only one factor having independent impact on survival in performance score > or = 2 (PCNSL p < 0.001, RR = 5.8).

[Autologous bone marrow transplantation in malignant blood diseases]. / Autolog knoglemarvstransplantation ved maligne blodsygdomme.

The authors present the organisation and preliminary experience with a comprehensive autologous bone marrow transplantation (ABMT) program in patients with malignant blood diseases. The procedure involves harvesting of bone marrow from patients in complete remission, purification of mononuclear cells and cryopreservation of these at -196 degrees C. After bone marrow cultures show that a sufficient number of hemopoietic progenitor cells (CFU-GM) are present in the marrow to reconstitute the patient, he/she is conditioned with chemo- (busulphan/cyclophosphamide (Bu + Cy)) or chemo/radiotherapy (total body radiation/cyclophosphamide (TBI + Cy)) in doses equal to those commonly used in allogeneic BMT. From February 1988 to July 1990 bone marrow (BM) was harvested from 24 patients. The median yield of mononuclear cells (MNC) was 1.2 x 10(8)/kg body weight (range 0.55-3.7). After buffy coat preparation, density gradient centrifugation, cryopreservation and thawing out, 0.60 x 10(8) MNC/kg (0.18-3.3) corresponding to 9.3 x 10(4) CFU-GM/kg (2.28-144) could be recovered. Twelve patients have received transplants, five with AML (after Bu + Cy conditioning), six with lymphoblastic lymphoma and one with Hodgkin's disease (with TBI + Cy conditioning). The median number of days to obtain greater than 1.0 x 10(9) leucocytes/l, greater than 0.5 x 10(9) neutrophils/l, greater than 50 x 10(9) thrombocytes/l and last requirement for erythrocyte transfusion were 21 (12-49), 28 (10-60), 55 (21-270) and 55 (12-129) days, respectively. Four patients had sepsis and the median duration of hospitalization was 39 (22-58) days. The most severe complications were seen in the AML patients, two of whom died during the posttransplant period (one of septicemia, one of thrombocytopenic bleeding).(ABSTRACT TRUNCATED AT 250 WORDS)

[Myelomatosis. A study of 138 patients treated with melphalan, prednisone and vincristine with particular attention to the prognostic value of a stage subdivision]. / Myelomatose. En undersøgelse af 138 patienter behandlet med melfalan, prednison og vincristin med saerligt henblik på en stadieinddelings prognostiske vaerdi.

With the object of evaluating three recognized prognostic stage subdivision systems for myelomatosis, retrospective data from 138 patients treated from 1976 to 1986 were employed. During this period, uniform therapeutic principles were employed, viz interval treatment with melphalan and prednisone supplemented, in cases of anaemia or raised serum creatinine, with vincristine. The prognostic significance for survival was calculated from variables at the time of diagnosis. The major prognostic factors were: age, tumour cell mass assessed by plasma cell percentage in the bone-marrow aspirate and/or M-component concentration, demonstration of Bence-Jones protein, renal function and the haemoglobin and calcium concentrations in the blood. Stage subdivision according the principles established by the Medical Research Council based on haemoglobin concentration and renal function were the best for assessing the prognosis in treated patients. Autopsy was performed on 55 out of the 96 patients who had died. The commonest cause of death was infection (75%).

Ultrastructural localization of acid phosphatase in immunologically defined neoplastic lymphocytic cells and hairy cells. A comparison between two different substrates.

The subcellular localization of acid phosphatase (AcP) in various immunologically-defined neoplastic lymphoid cells including hairy cells was investigated by electron microscopy. 2 substrates, naphthol-AS-BI-phosphoric acid (naphthol-AS-BI-P) and sodium beta-glycerophosphate, were compared. By incubation in naphthol-AS-BI-P containing medium, the reaction product was found located in granules, vesicles, the Golgi apparatus, the rough ER including the nuclear envelope in the cells of T ALL, T CLL and HCL. A typical pattern of reaction was observed for each of these disorders: enzyme-positive Golgi membranes and neighbouring granules, clustered in the nuclear notch in T cell-derived lymphoblasts; enzyme-positive granules around Gall bodies, aggregated paranuclearly in T CLL lymphocytes and enzyme-positive scattered cytoplasmic granules and vesicles in hairy cells. Enzyme activity was occasionally seen in singly-occurring granules in the cells of cALL, B CLL and B PLL, rarely in other substructures. With the Gomori method using beta-glycerophosphate as substrate, the enzyme reaction was limited primarily to lysosomal sites and was seldom observed in other organelles. Tartrate-resistant AcP was found in the majority of hairy cells and in a few prolymphocytes, located in the same structures as AcP without tartrate.

Ultrastructural localization of acid alpha-naphthylacetate esterase in human normal and neoplastic lymphocytic and monocytic cells and in hairy cells.

The ultrastructural localization of acid alpha-naphthylacetate esterase (ANAE) activity was studied in normal and neoplastic human monocytic and lymphocytic cells including hairy cells. Normal monocytes and malignant monocytic cells from cases of AML-M4 and -M5 (FAB-classification) displayed fundamentally the same ANAE staining pattern with reaction products localized to the external surface of the plasma membrane and to small vesicles close to this membrane, more rarely to larger intracytoplasmic vesicles containing endocytosed material or cellular debris. The enzyme activity of the neoplastic cells increased with morphological differentiation. Certain normal blood lymphocytes and T cell-derived CLL cells showed the reaction product associated with paranuclearly located clusters of vesicular structures, extending from the membranes into the adjacent cytoplasm. Gall bodies were often found in the vicinity and were invariably positive for ANAE. Now and then, plasma membrane activity was present, but never as pronounced as in monocytes. Hairy cells demonstrated a pattern of reaction very similar to that of monocytic cells, whereas B cell-derived CLL cells and lymphoblasts of T- and common type ALL were generally non-reactive.

Stereologic analysis of the ultrastructure in isolated human T and non-T lymphoid cells. II. Data on blasts in ALL; correlation with immunologic studies and FAB-morphology.

Leukemic cells from 20 cases of acute lymphoblastic leukemia (ALL), examined for T and B markers and classified according to FAB guidelines, were analyzed by electron microscopy. Using stereologic methods a quantitative morphologic characterization of the average blast, assumed to be of clonal origin and thus representative of the whole population, was obtained within each subset. Comparative studies of the ultrastructure of the T, B and non-T, non-B blast on one hand and of the FAB category L1 and L2 on the other were performed. No differences of cell volumes, total cell surface areas, nuclear volumes and surface areas or volumes of nuclear compartments were observed between the immunologically defined subsets. Minor variations were seen in the cellular surface contour, the B blast tending to be more irregular than the T blast. Features most predictive of the immunologic cell type were abundant rough ER in B-derived ALL, increasing with plasmacytoid differentiation, and an increase in dense granules which were often clustered in the vicinity of a well-developed Golgi complex in T ALL. The light microscopic criteria of the FAB classification were nearly all confirmed at the EM-level except that nuclear irregularity was observed to the same degree in both categories. Other differences not related to the FAB scheme were encountered in the volumes of the Golgi complex and of the mitochondrial compartment. Objective criteria as quantitative estimates of cellular structures may contribute to an improved subclassification in ALL.

Stereologic analysis of the ultrastructure of isolated human T and non-T lymphoid cells. III. Studies in chronic lymphoid leukemias, hairy cell leukemia and some malignant lymphomas.

Malignant cells from 9 cases of chronic lymphocytic leukemia (CLL), 4 cases of prolymphocytic leukemia (PLL), 4 cases of hairy cell leukemia (HCL), 4 cases of malignant lymphoma of centrocytic type and 3 cases of malignant lymphoma of lymphoblastic type (Kiel classification), all examined for T and B markers, were analysed by electron microscopy. Stereological methods were applied to assess relative and absolute values concerning the whole cell and nuclear and cytoplasmic components of the average cell in each population, and comparisons were made between the morphologically and immunologically defined subsets. The CLL-lymphocyte possessed the smallest cell volume, a high nucleo-cytoplasmic volume ratio, densely packed heterochromatin, a small nucleolar volume and a sparse Golgi complex. The 7 B-derived cases were characterized by a larger volume of rough ER and a more irregular plasma membrane than the two T-derived cases, which typically displayed dense granules in paranuclear aggregations. The prolymphocyte could be distinguished from the CLL-cell by its larger cell volume, lower nucleo-cytoplasmic volume ratio, proportionally lesser heterochromatin, typically condensed at the periphery and around a prominent nucleolus. All 4 cases of PLL were of B-nature and shared the features of B-CLL regarding increased rough ER and low content of granules. The hairy cell exhibited the largest cell volume, the lowest nucleo-cytoplasmic volume ratio, an indented nucleus and a remarkable irregular cellular surface with long "hairy" processes. The cytoplasmic inclusions of ribosome-lamella complexes were recorded exclusively in hairy cells, in half of the patients. The centrocyte was characterized by a cell volume of intermediate size, a high nucleo-cytoplasmic volume ratio and the highest degree of nuclear irregularity recorded. The amount of rough ER was considerably less than in B-CLL and B-PLL. Finally, the blast from the cases of lymphoblastic lymphoma, all of T-nature, displayed a smooth plasma membrane, a high euchromatin-heterochromatin volume ratio and dense granules, characteristically clustered in the vicinity of the Golgi complex. Stereology on the ultrastructure of malignant lymphoid cells provides a more accurate characterization and may be helpful in classification.

Three different acid phosphatase patterns in leukaemic lymphoid T-cells.

The acid phosphatase pattern was studied in leukaemic cells from 8 patients with T-cell leukaemia (5 ALL and 3 CLL). In 2 cases the enzyme activity was focal granular with paranuclear localization as earlier demonstrated by other authors, while--in contrast to these findings--the enzyme activity in 4 cases demonstrated universal granular distribution. Almost all the cells from each patient showed the same picture. In the last 2 cases a mixed focal and universal granular pattern was observed, where half the cells possessed the focal form and the other half the universal form of granular activity. The two first-mentioned patterns were observed in cases of T-ALL as well as of T-CLL, while the mixed pattern was seen only in cases of T-ALL.