Challenges in lymphoma diagnosis in HIV positive patients in the South African setting

An increase in high grade B-cell lymphomas has been noted in HIV infection. Sub-Saharan Africa is the epicentre of the epidemic and in Gauteng, South Africa >90% of patients with high grade lymphoma tested positive for HIV infection. The diagnosis of lymphoma may be challenging in HIV because of reactive conditions which mimic lymphomas, the atypical clinical presentation and the atypical histological findings. The WHO classification divides lymphomas into discrete categories. Despite this, tumours in HIV positive patients commonly show atypical morphological, immunophenotypic, molecular and cytogenetic features, making exact classification difficult. This has lead to an increase in the diagnosis of the highly aggressive B-cell lymphoma, unclassifiable with features intermediate between DLBCL and BL. It appears likely that HIV-associated lymphomas represent a continuum of disease.

Recommendations for the management of adult chronic myeloid leukaemia in South Africa

INTRODUCTION

Chronic myeloid leukaemia (CML) is a chronic myeloproliferative disorder characterised by a chromosomal translocation between the long arms of chromosomes 9 and 22 [corrected] resulting in the formation of the BCR-ABL fusion gene. The management of CML has undergone major changes over the past decade. Novel treatment approaches have had a dramatic impact on patient outcomes and survival. Nevertheless, these outcomes can only be achieved in the context of expert management, careful monitoring of disease response, appropriate management of adverse events and timeous adjustments to therapy when responses are not achieved within stated time-frames.

AIM

With the advent of novel treatments providing molecular responses, both the monitoring and management of CML have become more complicated. The aim of these recommendations was to provide a pragmatic yet comprehensive roadmap to negotiate these complexities.

METHODS

Recommendations were developed based on local expert opinion from both the academic and private medical care arenas after careful review of the relevant literature and taking into account the most widely used international guidelines. About five meetings were held at which these recommendations were discussed and debated in detail.

RESULTS

A comprehensive set of recommendations was compiled with an emphasis on diagnosis, investigation, treatment and monitoring of disease. Careful attention was given to circumstances unique to South Africa, funding constraints, availability and access to laboratory resources, as well as the effects of concurrent HIV infection.

CONCLUSION

Most patients with CML can live a reasonably normal life if their disease is appropriately managed. These recommendations should be of value to all specialists involved in the treatment of haematological disorders.

Granulocytic sarcoma in children with acute myeloblastic leukemia and t(8;21)

BACKGROUND

Granulocytic sarcomas (GS) have been associated with t(8;21). The prognosis of patients with GS is generally regarded as being less favorable than of patients with acute myeloblastic leukemia (AML). GS occurs relatively commonly in Africa and has been reported to affect 10-25% of black children presenting with AML. We sought to establish the incidence of GS in our pediatric population, to determine whether an association with t(8;21) existed, and to report on the outcome of these cases in a single series.

PROCEDURE

The records of consecutive pediatric patients treated for de novo AML in Johannesburg between January 1985-December 1995 were reviewed. Fifteen cases of GS among a total of 88 cases of AML presented to the Paediatric Haematology/Oncology Clinics of the Johannesburg and Baragwanath Hospitals. Fourteen (93%) of these patients were black male children.

RESULTS

All 9 cases of orbital GS (60%) and almost all cases with concurrent AML M2 had t(8;21). This translocation was present in only 4 n(8.5%) of the remaining 47 AML cases without GS for which cytogenetic data were available. One case presented with a complex chromosomal translocation not previously associated with GS. The median disease-free survival of the GS patients, using conventional chemotherapy treatment protocols, was significantly better than for the patients with AML and no GS (P = 0.0004).

CONCLUSIONS

Our data support a strong association between orbital GS, t(8;21), and AML M2 in the pediatric population. This entity occurred virtually exclusively in black male children at presentation. One third of these children who presented with AML had a GS. The favorable prognosis noted in our GS patients on standard induction and intensification therapy without local irradiation conflicts with some previous reports but is consistent with the favorable outcome documented in AML with t(8;21).

12p rearrangement and DNA amplification mapped by comparative genomic hybridization in a patient with secondary myeloid leukemia

Rearrangements of the short arm of chromosome 12 (12p) are a common finding in hematologic malignancies. There has recently been considerable interest in chromosome 12 abnormalities in view of the mapping of the TEL gene to 12p13 and frequent 12p interstitial deletions. Overrepresentation of 12p sequences is, on the other hand, a consistent finding in testicular germ cell tumor (TGCT), and the 12p11.2-p12.1 subregion has been found to be specifically involved. We have studied a secondary leukemic patient whose cells contained 12p rearrangements with a view to clarifying the underlying molecular events. Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) have revealed the presence of 12p11 breakpoints on both 12 homologs as well as amplification of 12p11-p12-derived sequences. Six YACs and a cosmid probe have been used in an attempt to map the amplification unit on 12p. The two YACs contigs WC-1468 and WC-985 were not amplified, and our results suggested a small amplicon localized in the 12p11.2-p12 subregion. We speculate that this region harbors gene(s) which are critical in tumor formation and could be involved in both TGCT and our patient. Whether the same gene(s) are involved in both amplification and translocation is unknown.

1;17 translocations and other chromosome 17 rearrangements in human primary neuroblastoma tumors and cell lines

We report on the finding of a t(1;17) in two primary neuroblastomas. Subsequent fluorescence in situ hybridization (FISH) analysis revealed the presence of 1;17 translocations in four out of nine neuroblastoma cell lines. The chromosome 1 short arm breakpoints were determined using region-specific probes. FISH screening also demonstrated or confirmed the presence of 11;17 translocations in three cell lines and other chromosome 17 rearrangements in those cell lines that did not carry a t(1;17) or t(11;17). Our data extend previous cytogenetic findings and suggest that, in addition to the known involvement of chromosome 1, one or more genes on chromosome 17 also play a role in neuroblastoma development.

Lack of involvement of T-lymphocytes in the leukaemic population during prolonged chronic phase of Philadelphia chromosome positive chronic myeloid leukaemia

Nine patients with prolonged (> 2 years) chronic phase chronic myeloid leukaemia (CML) were investigated for the presence of T-cell involvement in the leukemic clone. Pure populations of peripheral blood T-cell populations were obtained by culturing separated mononuclear cells in the presence of pokeweed mitogen and IL2, until cultures showed > 99% pure T-cells. Purified T-cells and bone marrow and peripheral blood hematopoietic precursors were analysed for the presence of bcr-abl mRNA transcripts following RNA extraction and message amplification using polymerase chain reaction. In none of the 9 patients was bcr-abl mRNA found in T-lymphocytes while in all cases such transcripts were found in bone marrow and peripheral blood hematopoietic cells. Failure to detect T-cell involvement in patients with prolonged chronic phase CML using techniques designed to enhance even low level involvement of these cell populations supports the view that acquisition of the Ph chromosome abnormality does not occur in the totipotent stem cells but in more committed precursor cell/s with multilineage capacity but which only rarely retain the capacity for T-cell differentiation.

Derivative (11)t(7;11)(q11;q24) in a child with acute megakaryoblastic leukemia

We document the clinical, morphologic, and cytogenetic findings in a 2 1/2-year-old patient with acute megakaryoblastic leukemia. Cytogenetic analysis of peripheral blood leukemic cells revealed the presence of a der(11)t(7;11)(q11;q24). Chromosome 7 involvement is observed in nearly half of all cases of megakaryoblastic leukemias, however, the type of abnormality differs widely from one case to another. The der(11)t(7;11)(q11;q24) described here is the first reported to our knowledge.

Translocation t(1;7) revisited. Report of three further cases and review

Three white patients, two with myelofibrosis and one with refractory anemia, presented with a t(1;7). The clinical and cytogenetic findings are discussed in the context of 45 cases already published. Rather than the specific association of t(1;7) with a particular hematologic disorder, a review of the literature strongly suggests correlation with therapeutic or environmental exposure to toxic substances. The proposed mechanisms to explain the origin of t(1;7) are briefly reviewed.