Detection of API2-MALT1 Fusion Transcripts in Cytologic Specimens of Patients with Pulmonary Mucosa-Associated Lymphoid Tissue Lymphoma


Mucosa-associated lymphoid tissue (MALT) lymphoma constitutes up to 90% of primary pulmonary lymphomas, but its diagnosis is often difficult.API2-MALT1 fusion is specific to MALT lymphoma and is detected in nearly half of the pulmonary cases. Cytologic examinations have played a pivotal role in the diagnosis of pulmonary tumors; however, cytologic specimens have only infrequently been used for molecular studies. In this study, we performed a multiplex reverse transcription-polymerase chain reaction (RT-PCR) assay to detect theAPI2-MALT1 fusion transcript in archival cytologic specimens used as RNA sources. We studied 3 pulmonary MALT lymphoma cases that were positive for the fusion gene as detected with RNA extracted from diagnostic histologic specimens. In 1 case, a conventional PCR clonality assay for the immunoglobulin heavy chain gene rearrangement failed to detect the monoclonality. In all 3 cases, the fusion transcript was successfully detected in the cytologic specimens of sputum, bronchoalveolar lavage fluid, bone marrow smears, and pleural effusions. This finding suggests that such specimens can be used as RNA sources in multiplex RT-PCR assays for theAPI2-MALT1 fusion transcript. The detection ofAPI2-MALT1 fusion as carried out with these specimens would be useful as an ancillary assay for the diagnosis, staging, and follow-up of pulmonary MALT lymphoma.


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Correspondence to Hiroshi Inagaki or Chunmei Li or Mitsukuni Okabe or Mitsunori Nishikawa or Takashi Niimi or Shinsuke Iida or Ryuzo Ued.

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Inagaki, H., Li, C., Okabe, M. et al. Detection of API2-MALT1 Fusion Transcripts in Cytologic Specimens of Patients with Pulmonary Mucosa-Associated Lymphoid Tissue Lymphoma. Int J Hematol 82, 59–62 (2005).

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Key words

  • Pulmonary MALT lymphoma
  • Multiplex RT-PCR
  • API2-MALT1 fusion
  • Cytologic specimens
  • Molecular diagnosis