Masakatsu Yonezumi

API2-MALT1 chimeric transcripts involved in mucosa-associated lymphoid tissue type lymphoma predict heterogeneous products

Recent progress in molecular analysis of low-grade B cell lymphoma has revealed that API2 at 11q21 and a novel gene, MALT1 at 18q21, are involved in t(11;18)(q21;q21), a characteristic chromosome aberration for mucosa-associated lymphoid tissue (MALT) type lymphoma. We describe here the establishment of a reverse transcription-polymerase chain reaction (RT-PCR) assay that we used to analyze 22 cases of MALT lymphoma. All five cases that were shown to possess t(11;18)(q21;q21) showed the specific amplification of API2-MALT1 chimeric transcripts. Of the remaining 17 cases for which cytogenetic data were not available, three cases demonstrated the presence of fusion transcripts, indicating that a significant percentage of MALT lymphoma cases of the present series appeared to possess t(11;18). A single fragment was observed in each of these cases, but the size varied from case to case. Sequencing analysis revealed that there are two breakpoints in API2 and three in MALT1, and that all of the fusion transcripts are in-frame. On the basis of these results, four kinds of chimeric proteins can be predicted for the present series. Thus, the RT-PCR assay used here should serve as an effective molecular tool for understanding molecular pathogenesis and the clinical significance of API2-MALT1 for MALT lymphomas.

Helicobacter pylori and the t(11;18)(q21;q21) Translocation in Gastric Low-grade B-Cell Lymphoma of Mucosa-associated Lymphoid Tissue Type

The reported regression of mucosa‐associated lymphoid tissue (MALT) type gastric low‐grade Bcell lymphoma following treatment for Helicobacter pylori (H. pylori) infection has not yet been comprehensively analyzed, especially in relation to the recently identified c‐IAP2‐MALT1/MLT gene alteration resulting from the t(11;18)(q21;q21) chromosomal translocation found in MALT lymphoma. The relationship between MALT lymphomas and H. pylori was investigated in 30 patients who received an antibacterial treatment. Patients were followed up by means of endoscopy and biopsy. Molecular genetic analyses focused on the presence or absence of the immunoglobulin heavy chain (IgH) gene and/or MALT1/MLT gene alteration resulting from t(11;18)(q21;q21) translocation. H. pylori was positive in 26 of the 30 patients. The overall success rate of cure of H. pylori infection was 96% (25/26). Thirteen patients (52%) showed complete remission (CR) of lymphoma, nine (36%) partial remission (PR), and three (12%) registered no change (NC). Statistical analysis revealed significant differences between CR and PR/NC patients in age (< 60 or 60), in lymphoma location (single or multiple sites) and in the presence or absence of gene rearrangement before eradication (P< 0.05). Endoscopy showed a cobblestone appearance only in PR cases and polypoid features predominantly in NC cases. Two NC patients with polypoid gross appearance showed rearrangements involving either c‐IAP2 or MALT1 gene in Southern blot analysis, while none of seven other resected patients with non‐polypoid superficial gross appearance showed rearrangement. Gastric MALT lymphoma could be pragmatically subdivided into three groups, CR (MALT‐A), PR (MALT‐B), and NC (MALT‐C) on the basis of the reaction to eradication of H.pylori. We speculate that MALT‐A may represent an incipient neoplasm or dysplasia, MALT‐B a neoplasm activated by antigenic stimulation of H. pylori, and MALT‐C a lymphoma independent of H. pylori. Polypoid lesions in MALT‐C were associated with c‐IAP2‐MALT1/MLT gene alteration resulting from t(11;18)(q21;q21). This classification is thought to be clinically significant for deciding the most appropriate mode of treatment of MALT‐type lymphoproliferative disorders.

Detection of AP12-MALT1 chimaeric gene in extranodal and nodal marginal zone B-cell lymphoma by reverse transcription polymerase chain reaction (PCR) and genomic long and accurate PCR analyses.

t(11;18)(q21;q21) has been recognized as a characteristic chromosomal translocation in mucosa‐associated lymphoid tissue (MALT)‐type lymphoma, and recent studies have demonstrated that this translocation results in the chimaeric transcript of API2 (apoptosis inhibitor 2)‐MALT1 (mucosa‐associated lymphoid tissue lymphoma translocation gene 1). In this study, we used reverse transcription polymerase chain reaction (RT–PCR) to analyse the incidence of this fusion product in a large series of MALT lymphoma, nodal marginal zone B‐cell lymphoma (nMZBCL) and extranodal diffuse large B‐cell lymphoma (DLBL) cases. RT–PCR analysis revealed that 17 of the 95 (17·9%) MALT lymphomas but none of the nine nMZBCLs or 16 DLBLs had API2‐MALT1 fusion transcripts. The incidence of API2‐MALT1 varied among MALT lymphomas arising from different sites and was highest for pulmonary MALT lymphomas (10 out of 16 cases, 62·5%). The presence of the API2‐MALT1 fusion gene was also confirmed by long and accurate (LA)–PCR with genomic DNA, and the result correlated well with that obtained with the RT–PCR assay, thus demonstrating the usefulness of LA–PCR for the detection of the API2‐MALT1 fusion gene.

Stability and subcellular localization of API2-MALT1 chimeric protein involved in t(11;18) (q21;q21) MALT lymphoma.

t(11; 18) (q21; q21) is a chromosomal aberration specific to low-grade mucosa-associated lymphoid tissue (MALT) lymphoma, and generates the chimeric product apoptosis inhibitor 2 (API2)-MALT1, which has been suggested to play an important role in MALT lymphomagenesis. However, little is known about the characteristics of API2, MALT1, and API2-MALT1 proteins. We therefore investigated the subcellular localization and stability of these products. API2 was localized in the nucleus and the cytoplasm, and MALT1 and API2-MALT1 in the cytoplasm only. Western blot analysis showed that the products of API2 and MALT1 were unstable, while the API2-MALT1 product was stable. The API2 deletion mutants at the end of the C-terminal and the MALT1 deletion mutants at the end of the N-terminal were stable compared with the full-length products. These results indicate that the domains responsible for protein instability are located in the end of the C-terminal of API2 and in that of the N-terminal of MALT1, and also that API2-MALT1 became stable because it lacks these domains. It has been suggested that NF-κB activation plays an important role in the tumorigenesis of MALT lymphoma. Our findings further suggest that the stabilized expression of API2-MALT1 products may continuously stimulate the NF-κB activating pathway, thus leading to MALT lymphomagenesis.

Monoclonal origin of an esophageal carcinosarcoma producing granulocyte-colony stimulating factor

Carcinosarcomas are comprised of carcinomatous and sarcomatous elements, and their histogenesis remains unclear. The authors examined the serum concentrations of hematopoietic growth factors and performed immunohistochemical studies on an esophageal carcinosarcoma from a patient with marked granulocytosis to determine its histopathogenesis and clonality.

The t(11; 18)(q21; q21) translocation in H. pylori -negative low-grade gastric MALT lymphoma

The t(11; 18)(q21; q21) translocation in H. pylori -negative low-grade gastric MALT lymphoma

Aggressive sporadic histiocytic sarcoma with immunoglobulin heavy chain gene rearrangement and t(14;18)

Histiocytic sarcoma (HS) is a rare but aggressive malignant neoplasm of histiocytic lineage with a poor prognosis. Immunohistochemically, the neoplastic cells are positive for CD163, CD68, and lysozyme, and negative for B and T cell markers. However, molecular studies on the origin of the neoplastic cells remain inconclusive. A 54-year-old woman was admitted to our hospital because of painful swelling of the left knee. Examination revealed generalized lymphadenopathy and splenomegaly. HS was diagnosed according to morphologic and immunohistochemical features observed on biopsy of the left inguinal lymph node. The tumor demonstrated a clonal immunoglobulin heavy chain gene rearrangement and a clonal cytogenetic abnormality including t(14;18) which was confirmed by fluorescence in situ hybridization analysis showing the IgH/BCL2 fusion gene. The neoplastic cells were negative for PAX5, a B cell associated transcription factor, and positive for CEBPβ, a transcription factor mediating macrophage and myeloid differentiation. Positron emission tomography showed disseminated areas of increased 18F-fluorodeoxyglucose uptake in multiple lymph nodes, the liver, spleen, both lungs, both kidneys, and many bony sites. The patient received localized irradiation therapy followed by chemotherapy, she failed to respond and died of the disease progression. The case findings suggest lineage promiscuity or plasticity related to the pathogenesis of HS.

Analysis of T-cell repertoire and mixed chimaerism in a patient with aplastic anaemia after allogeneic bone marrow transplantation

Summary. We analysed 26 T‐cell receptor (TCR) β chain subfamilies (VB) of a patient with aplastic anaemia (AA) who underwent allogeneic bone marrow transplantation (allo‐BMT). The patient developed pancytopenia at d 80. The patients T cells were skewed in 10 of 26 TCR‐VB on d 83. These TCR‐VB, especially VB15, which were almost entirely CD8‐positive cells, were skewed throughout her clinical course. Chimaerism analysis of the CD8‐positive cells indicated that they were of recipient origin. Therefore, some immune responses induced by the recipient CD8‐positive T cells had an important role in pancytopenia in AA patients after allo‐BMT.

Aleukemic leukemia cutis in a patient with Philadelphia chromosome-positive biphenotypic leukemia

Aleukemic leukemia cutis is a rare condition characterized by the invasion of leukemic blasts into the skin before their appearance in the peripheral blood. Leukemia cutis usually occurs in patients with myeloid leukemia, especially the myelomonocytic and monocytic types of acute myeloblastic leukemia. We describe the case of a 62-year-old woman with aleukemic leukemia cutis who developed Philadelphia-positive acute leukemia 1 month after skin involvement. Leukemic cells expressed both myeloid and B-cell lineage surface markers, and monoclonal rearrangement of the immunoglobulin heavy chain was detected by Southern blot analysis. This report is the first of a case of aleukemic leukemia cutis preceding Philadelphia-positive biphenotypic leukemia.

Usefulness of magnifying endoscopic evaluation of the terminal ileum for a patient with graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

The gastrointestinal tract is one of the common targets of acute graft-versus-host disease (GVHD), but accurate diagnosis is difficult because of the nonspecific nature of complicated diseases and the lack of diagnostic findings by conventional endoscopy. Recently, a magnifying endoscope has been developed and used for examining microstructures of the mucosa. Herein, we report the first use of a magnifying endoscope for a patient with gastrointestinal (GI) GVHD. Magnified endoscopic findings of atrophic and coalescent villi of the terminal ileum reflect histological findings of GVHD. Magnifying endoscopy of the terminal ileum may be useful for early detection and follow-up of GI GVHD.