We report a case of transient myeloproliferative disorder (TMD) in a neonate without features of Down syndrome (DS) with clonal karyotype evolution, after apparent spontaneous resolution of TMD, but eventually progressing to acute megakaryoblastic leukemia (AMKL). The patient had petechiae, thrombocytopenia, and blastemia. Trisomy 21 with a satellited Y chromosome (Yqs) was found in proliferating blasts. A stimulated peripheral blood culture confirmed the constitutional origin of the Yqs, but did not reveal the presence of any trisomic 21 cell. By the age of 3 months, clonal chromosome evolution in the form of an interstitial deletion of the long-arm of chromosome 13 [del(13)(q13q31)] was detected along with trisomy 21 in unstimulated bone marrow cultures. However, remission was achieved without treatment at the age of 4 months. Trisomy 21 and del(13)(q13q31) were not identified in either cytogenetics or fluorescence in situ hybridization studies at that time. The child was asymptomatic until the age of 20 months when anemia and thrombocytopenia prompted a bone marrow biopsy, revealing changes consistent with AMKL. The remission proceeded by clonal karyotype evolution in a neonate with TMD demonstrates that clonal karyotype evolution does not indicate an immediately progressive disease. However, the development of AMKL after TMD in this case illustrates the increased risk for leukemia in TMD cases, even without DS. The gradual clonal evolution of the blasts in our patient suggests that "multiple hits" oncogenesis applies to TMD progression to acute leukemia.

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Six patients had blood and bone marrow manifestations characterized by the presence of morphologically immature or blastic B-lineage lymphoid cells expressing CD5 antigen. The median patient age was 70 years, and the male-to-female ratio was 5:1. The presence or degree of lymphadenopathy and splenomegaly was variable among this group at staging evaluation, although two patients did not have these features. One patient had an antecedent diagnosis of classical nodal mantle cell lymphoma, without prior morphologic blood or bone marrow involvement. Other patients lacked a history of underlying lymphoproliferative disorders. The median white blood cell count was 120 ؋ 10 9 /L. Most patients had thrombocytopenia, whereas only one patient had neutropenia at presentation. Leukemic peripheral blood cells in these six cases were small to medium in size with fine or granular nuclear chromatin and small or inconspicuous nucleoli. The pattern of marrow involvement was interstitial or diffuse, with cells showing immature nuclear features resembling acute leukemia or blastic lymphoma. All tumors demonstrated a consistent immunophenotype of B-cell lineage, surface immunoglobulin positivity, and CD5 antigen expression. The progenitor cell-associated markers CD34 and TdT were not expressed, and CD23 antigen was either negative (three of four cases) or only weakly present (one of four cases). The presence of a karyotypic t(11;14)(q13;q32) was documented in one tumor, whereas two other cases had BCL-1 gene rearrangements by either polymerase chain reaction or Southern blot analysis. Cyclin D1 mRNA overexpression was noted in three of four cases tested. This patient group was characterized by very poor overall survival (median, 3 months; range, 0.5 to 6 months). The aggregate clinical, pathologic, and genetic data in these unusual cases are consistent with de novo or predominant leukemic presentations of blastic mantle cell lymphoma. Accurate diagnosis in such cases is greatly facilitated by cytogenetic studies or the demonstration of BCL-1/ cyclin D1 abnormalities. The expression of surface immunoglobulin (SIg) generally signifies a mature B-cell phenotype and is usually accompanied by nuclear changes of chromatin condensation. However, exceptional lymphoid neoplasms characterized by blastic cytology and mature phenotype have been described. One example is a previous report of nine cases of "mature" B-cell acute lymphoblastic leukemia (ALL), characterized by non-L3 leukemic blast morphology and the presence of SIg positivity (1). These cases were phenotypically somewhat heterogeneous, although TdT was consistently negative in each case and CD10 expression was observed in all of five tumors tested for this antigen. Among these unusual blastic, SIg-positive leukemic cases, karyotypic analysis also revealed heterogeneity. Two tumors exhibited 8(q24) region translocations, implying C-MYC gene deregulation. Of interest, one of these lesions had a t(14;18) anomaly, in addition to 8(q24) rearrangement, suggesting blastic transformation of...

Lymphoplasmacytic lymphoma (LPL) and small lymphocytic lymphoma/chronic lymphocytic leukemia (SLL/CLL)are distinct clinicopathologic entities. Although some cases of SLL/CLL may show plasmacytic differentiation and be associated with monoclonal immunoglobulin in serum, such cases appear to be very rare, and if plasma cell differentiation were marked, differentiation of SLL/CLL from LPL could be difficult. We report a rare case of true CD5-positive small lymphocytic lymphoma/chronic lymphocytic leukemia with unequivocal plasmacytic differentiation. This case also showed an abnormality of chromosome 1p36 not previously described in small lymphocytic lymphoma/chronic lymphocytic leukemia.