Origins of "late" relapse in childhood acute lymphoblastic leukemia with TEL-AML1 fusion genes

Approximately 20% of childhood B-precursor acute lymphoblastic leukemia (ALL) has a TEL-AML1 fusion gene, often in association with deletions of the nonrearranged TEL allele. TEL-AML1 gene fusion appears to be an initiating event and usually occurs before birth, in utero. This subgroup of ALL generally presents with low- or medium-risk features and overall has a very good prognosis. Some patients, however, do have relapses late or after the cessation of treatment, at least on some therapeutic protocols. They usually achieve sustained second remissions. Posttreatment relapses, or even very late relapses (5-20 years after diagnosis), in childhood ALL are clonally related to the leukemic cells at diagnosis (by IGH or T-cell receptor [TCR] gene sequencing) and are considered, therefore, to represent a slow re-emergence or escape of the initial clone seen at diagnosis. Microsatellite markers and fluorescence in situ hybridization identified deletions of the unrearranged TEL allele and IGH/TCR gene rearrangements were analyzed; the results show that posttreatment relapse cells in 2 patients with TEL-AML1-positive ALL were not derived from the dominant clone present at diagnosis but were from a sibling clone. In contrast, a patient who had a relapse while on treatment with TEL-AML1 fusion had essentially the same TEL deletion, though with evidence for microsatellite instability 5(') of TEL gene deletion at diagnosis, leading to extended 5(') deletion at relapse. It is speculated that, in some patients, combination chemotherapy for childhood ALL may fail to eliminate a fetal preleukemic clone with TEL-AML1 and that a second, independent transformation event within this clone after treatment gives rise to a new leukemia masquerading as relapse. (Blood. 2001;98:558-564)

Molecular tracking of leukemogenesis in a triplet pregnancy

The occurrence of childhood acute lymphoblastic leukemia (ALL) in 2 of 3 triplets provided a unique opportunity for the investigation of leukemogenesis and the natural history of ALL. The 2 leukemic triplets were monozygotic twins and shared an identical, acquired TEL-AML1 genomic fusion sequence indicative of a single-cell origin in utero in one fetus followed by dissemination of clonal progeny to the comonozygotic twin by intraplacental transfer. In accord with this interpretation, clonotypic TEL-AML1 fusion sequences could be amplified from the archived neonatal blood spots of the leukemic twins. The blood spot of the third, healthy, dizygotic triplet was also fusion gene positive in a single segment, though at age 3 years, his blood was found negative by sensitive polymerase chain reaction (PCR) screening for the genomic sequence and by reverse transcription-PCR. Leukemic cells in both twins had, in addition to TEL-AML1 fusion, a deletion of the normal, nonrearranged TEL allele. However, this genetic change was found by fluorescence in situ hybridization to be subclonal in both twins. Furthermore, mapping of the genomic boundaries of TEL deletions using microsatellite markers indicated that they were individually distinct in the twins and therefore must have arisen as independent and secondary events, probably after birth. These data support a multihit temporal model for the pathogenesis of the common form of childhood leukemia.

[Clinical significance and frequency of the 11q23/MLL genetic molecular alteration in Chilean infants with acute leukemia]

BACKGROUND

Acute leukemia (AL) in infants generally shows distinctive biologic features and has a poor prognosis.

AIM

To study the frequency of the cytogenetic alteration of 11q23 chromosome or the recombination of MLL gene in infants less than 18 months old, with acute leukemia.

PATIENTS AND METHODS

We analyzed 37 cases of AL in infants less than 18 months of age diagnosed in Chile from 1989 to 1999. The clinical features and cytogenetic/molecular defects of 11q23MLL gene rearrangement and their influence in prognosis were determined.

RESULTS

There were 18 cases of acute Lymphoblastic leukemia (ALL) characterized by female sex (67%) high presenting leukocyte count (median 99 x 109/L), blast cells with a CD10 negative phenotype (50%) and 11q23/MLL rearrangement (39%). Molecular abnormalities of 11q23 were significantly associated with adverse prognosis, with an event free survival (EFS) of only 14 +/- 12%. Interestingly, infants with germ line 11q23 had a very good outcome with an EFS of 73 +/- 11% (p < 0.025). There were 19 cases of acute myeloblastic leukemia (AML) characterized by male sex (63%) high leukocyte count (median 93 x 109/L), FAB-MS morphology (53%) and 11q23/MLL rearrangement (53%). EFS was very poor, 20 +/- 9% and 33 +/- 4% for rearranged and germinal group respectively (p = NS), due to a high mortality rate during the first month of diagnosis.

CONCLUSIONS

These findings demonstrate that Chilean ALL infants with 11q23 abnormalities have a very poor prognosis. However those with germinal state can enjoy a prolonged disease free survival with the current treatment protocols.

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms and risk of molecularly defined subtypes of childhood acute leukemia

Low folate intake as well as alterations in folate metabolism as a result of polymorphisms in the enzyme methylenetetrahydrofolate reductase (MTHFR) have been associated with an increased incidence of neural tube defects, vascular disease, and some cancers. Polymorphic variants of MTHFR lead to enhanced thymidine pools and better quality DNA synthesis that could afford some protection from the development of leukemias, particularly those with translocations. We now report associations of MTHFR polymorphisms in three subgroups of pediatric leukemias: infant lymphoblastic or myeloblastic leukemias with MLL rearrangements and childhood lymphoblastic leukemias with either TEL-AML1 fusions or hyperdiploid karyotypes. Pediatric leukemia patients (n = 253 total) and healthy newborn controls (n = 200) were genotyped for MTHFR polymorphisms at nucleotides 677 (C-->T) and 1,298 (A-->C). A significant association for carriers of C677T was demonstrated for leukemias with MLL translocations (MLL+, n = 37) when compared with controls [adjusted odd ratios (OR) = 0.36 with a 95% confidence interval (CI) of 0.15-0.85; P = 0.017]. This protective effect was not evident for A1298C alleles (OR = 1.14). In contrast, associations for A1298C homozygotes (CC; OR = 0.26 with a 95% CI of 0.07--0.81) and C677T homozygotes (TT; OR = 0.49 with a 95% CI of 0.20--1.17) were observed for hyperdiploid leukemias (n = 138). No significant associations were evident for either polymorphism with TEL-AML1+ leukemias (n = 78). These differences in allelic associations may point to discrete attributes of the two alleles in their ability to alter folate and one-carbon metabolite pools and impact after DNA synthesis and methylation pathways, but should be viewed cautiously pending larger follow-up studies. The data provide evidence that molecularly defined subgroups of pediatric leukemias have different etiologies and also suggest a role of folate in the development of childhood leukemia.

Transplacental chemical exposure and risk of infant leukemia with MLL gene fusion

Infant acute leukemia (IAL) frequently involves breakage and recombination of the MLL gene with one of several potential partner genes. These gene fusions arise in utero and are similar to those found in leukemias secondary to chemotherapy with inhibitors of topoisomerase II (topo-II). This has led to the hypothesis that in utero exposures to chemicals may cause IAL via an effect on topo-II. We report a pilot case-control study of IAL across different countries and ethnic groups. Cases (n = 136) were population-based in most centers. Controls (n = 266) were selected from inpatients and outpatients at hospitals serving the same populations. MLL rearrangement status was derived by Southern blot analysis, and maternal exposure data were obtained by interviews using a structured questionnaire. Apart from the use of cigarettes and alcohol, very few mothers reported exposure to known topo-II inhibitors. Significant case-control differences were apparent for ingestion of several groups of drugs, including herbal medicines and drugs classified as "DNA-damaging," and for exposure to pesticides with the last two being largely attributable, respectively, to one nonsteroidal anti-inflammatory drug, dipyrone, and mosquitocidals (including Baygon). Elevated odds ratios were observed for MLL+ve (but not MLL-ve) leukemias (2.31 for DNA-damaging drugs, P = 0.03; 5.84 for dipyrone, P = 0.001; and 9.68 for mosquitocidals, P = 0.003). Although it is unclear at present whether these particular exposures operate via an effect on topo-II, the data suggest that specific chemical exposures of the fetus during pregnancy may cause MLL gene fusions. Given the widespread use of dipyrone, Baygon, and other carbamate-based insecticides in certain settings, confirmation of these apparent associations is urgently required.

Screening for herpesvirus genomes in common acute lymphoblastic leukemia

There is epidemiological evidence that infection may play a role in the etiology of childhood leukemia in particular common B cell precursor acute lymphoblastic leukemia. A panel of 20 leukemic samples (panel 1) was examined for the presence of four lymphotropic herpesviruses using conventional molecular techniques. A second independent panel of 27 leukemic samples (panel 2), along with 28 control peripheral blood samples from children with other forms of cancer, was tested for the presence of the same four viruses using sensitive real-time quantitative PCR. While herpesvirus genomes were detected, they were present at very low levels; detection rates and levels were similar in the leukemic and control panels. In addition we surveyed 18 leukemic samples (five from panel 1, six from panel 2 and a further seven samples not previously analyzed) using a degenerate PCR assay capable of detecting the genomes of known herpesviruses plus putative new members of the family. No novel herpesvirus genomes were detected suggesting that a herpesvirus is unlikely to be etiologically involved as a transforming agent in common acute lymphoblastic leukemia.

TEL-AML1 fusion gene frequency in paediatric acute lymphoblastic leukaemia in Brazil

We analysed 67 samples from Brazilian children of diverse ethnic origins with acute lymphoblastic leukaemia (ALL) for the presence of the TEL-AML1 fusion gene transcripts using reverse transcription polymerase chain reaction (RT-PCR). All 12 positive cases (20% of the 60 B-cell precursor ALL) had common (CD10+) ALL with a mean age of 4 years (range 1-10 years). We conclude that the frequency, age, distribution and clinical features of the TEL-AML1 fusion gene-positive ALL is similar in the diverse ethnic backgrounds of the Brazilian children to that in other countries with predominantly white Caucasian or oriental ethnicity. Apparent exceptions to this generality are discussed.

Prenatal origin of acute lymphoblastic leukaemia in children

BACKGROUND

There is little current insight into the natural history of childhood leukaemia or the timing of relevant mutational events. TEL-AML1 gene fusion due to chromosomal translocation is frequently seen in the common form of childhood acute lymphoblastic leukaemia. We investigated whether this abnormality arises prenatally.

METHODS

We identified, by reverse-transcriptase PCR screening of blood or bone marrow, TEL-AML1 fusion in 12 children, plus a pair of identical twins, aged 2-5 years from Italy and the UK, who had newly diagnosed acute lymphoblastic leukaemia. We amplified and sequenced the genomic TEL-AML1 fusion gene with a long-distance inverse PCR method. Primers were designed that could be used in short-range PCR to screen for patient-specific, leukaemia clone-specific TEL-AML1 genomic fusion sequences in neonatal blood spots from each child.

FINDINGS

We initially identified TEL-AML1 fusion sequences in blood spots from the identical twins, diagnosed with concordant acute lymphoblastic leukaemia at age 4 years, who shared a single or clonotypic TEL-AML1 sequence that suggested prenatal origin in one twin. Three children were excluded because control genes could not be amplified. Of the other nine patients, six had positive blood spots. Blood spots that were classified as negative were uninformative.

INTERPRETATION

Our findings showed that childhood acute lymphoblastic leukaemia is frequently initiated by a chromosome translocation event in utero. Studies in identical twins show however that such an event is insufficient for clinical leukaemia and that a postnatal promotional event is also required.

A lack of a functional NAD(P)H:quinone oxidoreductase allele is selectively associated with pediatric leukemias that have MLL fusions. United Kingdom Childhood Cancer Study Investigators

Rearrangements and fusion of the MLL gene with various alternative partner genes occur in approximately 80% of infant leukemias and are acquired during fetal hemopoiesis in utero. Similar MLL gene recombinants also occur in topoisomerase II-inhibiting drug-induced leukemias. These data have led to the suggestion that some infant leukemia may arise via transplacental fetal exposures during pregnancy to substances that form cleavable complexes with topoisomerase II and induce illegitimate recombination of the MLL gene. A structural feature shared by many topoisomerase II-inhibiting drugs and other chemicals is the quinone moiety. We assayed, by PCR-RFLP, for a polymorphism in an enzyme that detoxifies quinones, NAD(P)H:quinone oxidoreductase (NQO1), in a series (n = 36) of infant leukemias with MLL rearrangements versus unselected cord blood controls (n = 100). MLL-rearranged leukemias were more likely to have genotypes with low NQO1 function (heterozygous CT or homozygous TT at nucleotide 609) than controls (odds ratio, 2.5; P = 0.015). In contrast, no significant allele bias was seen in other groups of pediatric leukemias with TEL-AML1 fusions (n = 50) or hyperdiploidy (n = 29). In the subset of infant leukemias that had MLL-AF4 fusion genes (n = 21), the bias increase in low or null function NQO1 genotypes was more pronounced (odds ratio, 8.12; P = 0.00013). These data support the idea of a novel causal mechanism in infant leukemia involving genotoxic exposure in utero and modulation of impact on a selective target gene by an inherited allele encoding a rate-limiting step in a carcinogen detoxification pathway.

[Adult T cell leukemia lymphoma in Chile. A clinical pathologic and molecular study of 26 patients]

BACKGROUND

Adult T cell leukemia lymphoma is a lymphoproliferative syndrome etiologically associated to human T cell lymphotropic virus type I.

AIM

To describe the clinical and laboratory features of 26 Caucasian Chilean patients, with HTLV-I positive adult T-cell leukemia lymphoma (ATLL).

MATERIAL AND METHODS

Diagnostic criteria included clinical features, cell morphology, immunophenotype, HTLV-I serology and/or DNA analysis by Southern blot or PCR.

RESULTS

According to the clinical presentation, 12 cases had the acute ATLL form, 6 had a lymphoma, 4 the chronic form and 4 had smoldering ATLL. The median presentation age was 50 years, younger than the Japanese patients, but significantly older than patients from other South American countries (e.g. Brasil, Jamaica, Colombia). The main clinical features: lymphadenopathy, skin lesions and hepatosplenomegaly, were similar in frequency to those of patients from other countries, except for the high incidence of associated neurological disease. Tropical Spastic Paraparesis (TSP) in our series of ATLL, was seen in one third of the patients (8/26). A T-cell immunophenotype was shown in all 26 cases and HTLV-I serology was positive in 25/26 patients. Molecular analysis on the seronegative patient showed clonal integration of proviral HTLV-I DNA into the lymphocytes DNA, and thus he may have been a poor responder to the retroviral infection. Proviral DNA integration was also demonstrated in 15/16 patients being clonal in 10, polyclonal in 3 (all smoldering cases) and oligoclonal in one.

CONCLUSIONS

ATLL in Chile has similar clinical and laboratory features than the disease in other parts of the world, except for a younger age than Japanese patients but older than those from other Latin American countries and a high incidence of patients with associated TSP. Detailed morphological and immunophenotypic analysis of the abnormal circulating lymphocytes, together with the documentation of HTLV-I by serology and/or DNA analysis are key tests for the identification of this disease.

An E mu-BCL-2 transgene facilitates leukaemogenesis by ionizing radiation

Clonogenic murine B cell precursors are normally ultrasensitive to apoptosis following genotoxic exposure in vitro but can be protected by expression of an E mu-BCL-2 transgene. Such exposures are likely to be mutagenic. This in turn suggests that a level of in vivo genotoxic exposure that usually has minimal pathological consequences might become leukaemogenic when damaged cells fail to abort by apoptosis. If this were to be the case, then the cell type that becomes leukaemic and the chromosomal/molecular changes that occur would also be of considerable interest. We tested this possibility by exposing E mu-BCL-2 and wild-type mice of differing ages to a single dose of X-irradiation of 1-4 Gy. Young (approximately 4-6 weeks) transgenic mice developed leukaemia at a high rate following exposure to 2 Gy but adult mice (4-6 months) did not. Exposure to 4 Gy produced leukaemia in both young and adult transgenic mice but at a higher frequency in the former. Leukaemic cell populations showed clonal rearrangements of the IGH gene but in most cases analysed had immunophenotypic features of an early B lympho-myeloid progenitor population which has not previously been recorded in radiation leukaemogenesis. Molecular cytogenetic analysis of leukaemic cells by banded karyotype and FISH revealed a consistent double abnormality: trisomy 15 plus an interstitial deletion of chromosome 4 that was confirmed by LOH analysis.

Ionising radiation and leukaemia potential risks: review based on the workshop held during the 10th Symposium on Molecular Biology of Hematopoiesis and Treatment of Leukemia and Lymphomas at Hamburg, Germany on 5 July 1997

Unexplained clusters of childhood leukaemia have generated concern that they may be causally related to environmental exposure to ionising radiation. The workshop provides in-depth examination of the aetiology of childhood leukaemia, patterns of clustering exhibited by cases and the influence of exposure to ionising radiation. Special attention has been focussed on the EUROCLUS study of clustering of childhood leukaemia and monitoring of populations exposed to contamination following the Chernobyl accident. There is insufficient evidence to conclude that environmental ionising radiation exposure is a causative agent for small clusters such as that reported in the vicinity of the Krümmel nuclear facility

Backtracking leukemia to birth: identification of clonotypic gene fusion sequences in neonatal blood spots

Epidemiological evidence has suggested that some pediatric leukemias may be initiated in utero and, for some pairs of identical twins with concordant leukemia, this possibility has been strongly endorsed by molecular studies of clonality. Direct evidence for a prenatal origin can only be derived by prospective or retrospective detection of leukemia-specific molecular abnormalities in fetal or newborn samples. We report a PCR-based method that has been developed to scrutinize neonatal blood spots (Guthrie cards) for the presence of numerically infrequent leukemic cells at birth in individuals who subsequently developed leukemia. We demonstrate that unique or clonotypic MLL-AF4 genomic fusion sequences are present and detectable in neonatal blood spots from individuals who were diagnosed with acute lymphoblastic leukemia at ages 5 months to 2 years and, therefore, have arisen during fetal hematopoiesis in utero. This result provides unequivocal evidence for a prenatal initiation of acute leukemia in young patients. The method should be applicable to other fusion genes in children with common subtypes of leukemia and will be of value in attempts to unravel the natural history and etiology of this major subtype of pediatric cancer.

Aetiology of acute leukaemia

Ionising radiation, in high dose and with acute exposure, is a factor that has been implicated in leukaemogenesis, but what is the evidence for leukaemogenesis and exposure to diagnostic X-rays, to natural terrestrial or cosmic ionising radiation, to electromagnetic fields, or to nuclear energy? Why is population mixing and infection a possible explanation for the clusters of childhood acute leukaemias around the nuclear processing plants of Sellafield and Dounreay? These questions, as well as how chemical agents, including therapeutic substances, might contribute to leukaemogenesis, are discussed in this last article in the leukaemia series.

Clustering of childhood leukaemia in Hong Kong: association with the childhood peak and common acute lymphoblastic leukaemia and with population mixing

Incidence data of childhood leukaemia (CL) in Hong Kong (1984-90) have been analysed for evidence of variation between small areas. All cases (n=261) were classified by morphological cell type, with the majority (n=205) being acute lymphoblastic leukaemia (ALL), and haematological review has permitted immunophenotypic classification for 73% of these. The data have been examined for evidence of spatial clustering within small census areas (TPUs) and for association with population mixing, with attention focused on those subgroups (especially the childhood peak of ALL--taken here to be diagnoses in children from 24 months up to the seventh birthday--and common ALL) which, it has been hypothesized, may be caused by unusual patterns of exposure and response to common infections. For the whole of Hong Kong, there was evidence of spatial clustering of ALL at ages 0-4 years (P = 0.09) and in the childhood peak (P<0.05). When these analyses were restricted to TPUs where extreme population mixing may have occurred, overall incidence was elevated and significant evidence of clustering was found for ALL (P<0.007) at these ages and for the common ALL in the childhood peak (P = 0.032). Replication of the analyses for subsets of leukaemia that were not dominated by the childhood peak of ALL found no evidence of clustering. This is the first investigation of an association between population mixing and childhood leukaemia in Asia and the first to include clustering and to consider particular subsets. The results are supportive of the 'infectious' aetiology hypothesis for subsets of childhood leukaemia, specifically common ALL in the childhood peak.

ts BCR-ABL kinase activation confers increased resistance to genotoxic damage via cell cycle block

Using a temperature-sensitive mutant of the p210 BCR-ABL gene, transfected into a growth factor-dependent cell line (BaF3), we show that transient BCR-ABL kinase expression increases single cell and clonogenic resistance to apoptosis arising from genotoxic damage induced by ionizing radiation and VP-16/etoposide. This effect is achieved in the absence of any detectable changes in the levels of BCL-2, BAX or BCL-x proteins and is independent of proliferative, MAP kinase-dependent effects of BCR-ABL kinase. In contrast to parental cells that transiently arrest in G2 and then apoptose, p210 BaF3 cells show a pronounced and sustained G2 arrest following radiation coupled with enhanced phosphorylation of cdc2. A cell cycle block in early M phase induced by the mitotic spindle poison, nocodazole, does not provide protection from apoptosis. Reversal of G2 arrest by caffeine abolishes the protective effect of BCR-ABL kinase. These data provide further insight into the transforming properties of BCR-ABL and are relevant to the clinical intransigence of Ph-positive leukaemias.

Regulation of the myeloperoxidase enhancer binding proteins Pu1, C-EBP alpha, -beta, and -delta during granulocyte-lineage specification

We have compared the molecular architecture and function of the myeloperoxidase upstream enhancer in multipotential versus granulocyte-committed hematopoietic progenitor cells. We show that the enhancer is accessible in multipotential cell chromatin but functionally incompetent before granulocyte commitment. Multipotential cells contain both Pu1 and C-EBP alpha as enhancer-binding activities. Pu1 is unphosphorylated in both multipotential and granulocyte-committed cells but is phosphorylated in B lymphocytes, raising the possibility that differential phosphorylation may play a role in specifying its lymphoid versus myeloid functions. C-EBP alpha exists as multiple phosphorylated forms in the nucleus of both multipotential and granulocyte-committed cells. C-EBP beta is unphosphorylated and cytoplasmically localized in multipotential cells but exists as a phosphorylated nuclear enhancer-binding activity in granulocyte-committed cells. Granulocyte colony-stimulating factor-induced granulocytic differentiation of multipotential progenitor cells results in activation of C-EBP delta expression and functional recruitment of C-EBP delta and C-EBP beta to the nucleus. Our results implicate Pu1 and the C-EBP family as critical regulators of myeloperoxidase gene expression and are consistent with a model in which a temporal exchange of C-EBP isoforms at the myeloperoxidase enhancer mediates the transition from a primed state in multipotential cells to a transcriptionally active configuration in promyelocytes.

[Immunophenotype. Clinical and laboratory features of acute lymphoblastic leukemia in Chile. Study of 500 children and 131 adults]

We describe the clinical features and immunophenotype of 500 children and 131 adults with acute lymphoblastic leukemia (ALL), diagnosed between 1984 and 1993. Cases were classified, according to immunophenotype in B-cell ALL with three subtypes (pro-B or null, common and B) and T-cell ALL. Among children, common ALL accounted for 74% of cases and pro-B all was more common in children of less than one year (14%). B ALL was observed in 2% of children. Ten percent of children, mostly males, had T-cell ALL. The third part of these children had high leukocyte counts and a mediastinal mass. Children from Mapuche origin, compared with Caucasian children had a lower proportion of common ALL (36 and 74% respectively) and a higher proportions of T-cell ALL (41 and 10% respectively). Among adults common ALL was the most common phenotype (72%) followed by T-cell ALL (15%), pro-B ALL (11%) and B-cell ALL (2%). There was a lower incidence of children with common ALL with positive cytoplasmic immunoglobulin compared to North American or European studies (2 and 15-33% respectively) and a higher proportion of adults with common ALL compared with pro-B cell ALL, in contrast to European studies that show a higher proportion of patients with pro-B cell ALL. No other immunophenotypic, clinical or laboratory differences were observed with ALL from developed countries. It is concluded that the immunophenotyping of ALL allows a more precise diagnosis of this disease.

Rapid intraclonal switch of lineage dominance in congenital leukaemia with a MLL gene rearrangement

We describe a case of neonatal mixed lineage leukaemia which presented with a dominant B progenitor lymphoblast population plus a minor monocytic component. Treatment of the patient with corticosteroid and Ara-C resulted in loss of lymphoblasts and a rapid (within 7 days) increase and dominance of the monocytic component. The common clonal origin of the two cell types was evident from the identical rearrangement in the MLL gene and a shared rearrangement of one IGH allele. In common with other neonatal or infant ALL with MLL gene rearrangements, this leukaemia may have originated in a common B-monocytic lineage stem cell during foetal haemopoiesis. The observations further suggest that the therapeutic impact of the MLL gene rearrangement is to some extent dependent on the cellular context in which it is expressed.

HTLV-I positive progressive spastic paraparesis (TSP) associated with a lymphoid disorder in three Chilean patients

We describe the clinical and laboratory features in three Caucasian Chilean patients with tropical spastic paraparesis (TSP) associated with/or preceded by a lymphoproliferative disorder involving cutaneous lesions and localised lymphadenopathy. The neurological symptoms and signs were characteristic of TSP and CSF examination revealed the presence of oligoclonal bands. All three patients had a moderate leucocytosis (10-14 x 10(9)/l) with eosinophilia and a minority (2-4%) of circulating atypical polylobed or ATLL-like lymphocytes. Lymph node histology showed a diffuse pattern of infiltration (1 case) and marked expansion of the paracortical zone with convoluted lymphocytes and immunoblasts (2 cases). Skin biopsy demonstrated a dermal lymphoid infiltration with epidermotropism. Antibodies to HTLV-I were detected in the serum and CSF in the three patients and Southern blot analysis of peripheral blood mononuclear cells showed a monoclonal integration of HTLV-I proviral DNA in one case whereas in the two others the pattern was indicative of low level polyclonal integration. All three patients were treated with prednisolone and one with PUVA with transient partial response on the skin and neurological manifestations. Two patients died months to 5 years from presentation and the other is alive 12 years from diagnosis with active neurological and skin disease. The simultaneous occurrence of HTLV-I associated TSP with smouldering ATLL and a cutaneous ATLL or pre-leukaemic form is discussed.