Yang O. Huh

Summary: Chromosomal translocations that involve MYC, characteristic of Burkitt lymphoma, are rare in chronic lymphocytic leukaemia (CLL). We report the clinical, morphological, immunophenotypic, cytogenetic and molecular genetic features of eight CLL cases with MYC rearrangement. The patients, five men and three women (median age, 71 years) had bone marrow involvement and an absolute peripheral blood lymphocytosis; five had lymphadenopathy; seven had splenomegaly. Prolymphocytes were increased (≥10%) in all cases. Six cases were classified as CLL with increased prolymphocytes (CLL/PL; prolymphocytes 10–55%), and two were classified as CLL in prolymphocytic transformation (CLL/PT; prolymphocytes >55%). All cases co‐expressed CD5, CD19, and CD23; five of eight expressed ZAP‐70. Of seven cases tested, four had mutated and three had unmutated IGHV genes. Conventional cytogenetic studies demonstrated t(8;14)(q24·1;q32) in five cases, t(8;22)(q24·1;q11) in two cases, and t(2;8)(p12;q24·1) in one case. Seven cases contained additional chromosomal abnormalities. All patients received combination chemotherapy. Two developed Epstein–Barr virus (EBV)‐associated diffuse large B‐cell lymphomas (DLBCL) that were clonally unrelated to the CLL. At follow‐up, two patients are alive, four died of underlying disease, one died of EBV‐associated DLBCL, and one died of an unrelated cancer. In summary, MYC rearrangement, which occurs rarely in CLL patients, is associated with increased prolymphocytes, complex cytogenetic abnormalities, and a poor prognosis.

Summary: The t(14;19)(q32;q13), involving the BCL3 locus at chromosome 19q13 and the immunoglobulin heavy chain gene at 14q32, is a rare recurrent cytogenetic abnormality identified in B‐cell neoplasms, most of which have been classified as chronic lymphocytic leukaemia (CLL) in the literature. We describe the clinicopathological, immunophenotypic and cytogenetic findings in seven patients with B‐cell neoplasms associated with t(14;19)(q32;q13). There were five men and two women, with a median age of 48 years (range 33–68). All had absolute lymphocytosis, six had lymphadenopathy, and one had splenomegaly. Lymphocytes in blood and bone marrow aspirate smears were predominantly small and cytologically atypical. Flow cytometric immunophenotyping showed an atypical immunophenotype with low CLL scores. The growth pattern in bone marrow biopsy specimens was interstitial to diffuse; immunohistochemical stains were positive for bcl3 and negative for cyclin D1. Lymph node biopsy specimens of two patients revealed total architectural effacement by neoplasm with proliferation centres. In addition to t(14;19), cytogenetic studies demonstrated trisomy 12 in five patients. These results suggest that B‐cell neoplasms with the t(14;19)(q32;q13) present frequently as leukaemia composed of small B‐lymphocytes and share many features with CLL. However, these neoplasms also differ from CLL cytologically and in their immunophenotype.

The significance of terminal deoxynucleotidyl transferase (TdT) expression in acute myelogenous leukemia (AML) remains controversial. Therefore, we studied TdT expression by flow cytometry in 120 previously untreated patients with AML or myelodysplastic syndrome (MDS) to determine the distribution of TdT-positive blasts and the intensity of TdT expression and to seek clinically significant associations. TdT expression measured by flow cytometry (flow TdT%) was heterogeneous, ranging from 0.1% to 87% (median, 8.5%), and 74 patients (62%) had at least 5% TdT-positive blasts. TdT positivity was associated with the M0 or M1 subtype and with expression of CD34 and CD7. No significant correlation was found between TdT expression and type of cytogenetic abnormality or rearrangement of immunoglobulin or T-cell receptor genes. Remission lasted longer in patients with a flow TdT% < 5 than in patients with a flow TdT% > 5 (median, 95 weeks vs 55 weeks, p = 0.02); however, complete remission rates did not differ when patients were classified by initial flow TdT%. Survival was slightly better for patients with flow TdT% less than 5%. Among patients with a flow TdT% > 5%, those with a higher TdT intensity survived longer than those with a lower intensity. These data suggest that quantitative TdT measurement may contribute to prognostic estimate in AML patients.