title: Bronchus-associated lymphoid tissue lymphoma stage IV with subsequent histologic transformation to an aggressive lymphoma: A case report.
abstract: BACKGROUND
  Extranodal marginal B-cell lymphoma of bronchus-associated lymphoid tissue is a rare entity accounting for less than 1% of all lymphomas. We report a case of a low-grade bronchus-associated lymphoid tissue lymphoma stage IV with transformation to an aggressive large B-cell lymphoma.
  
  
  METHODS
  A 59-year-old African-American man was incidentally found to have a bronchus-associated lymphoid tissue lymphoma involving the bilateral lower lobes of his lungs. In addition, bone marrow involvement was discovered. His course was indolent with only some mild respiratory symptoms. He received single agent treatment with rituximab. No evidence of progression was seen at the end of receiving this regimen. Two years after treatment our patient presented with B symptoms. Imaging now showed significant increase in the size of the lung masses with cavitation of the right lower lobe mass. A repeat transbronchial biopsy suggested transformation to an aggressive diffuse large B-cell lymphoma.
  
  
  CONCLUSIONS
  This case illustrates a rare bronchus-associated lymphoid tissue lymphoma stage IV with histologic transformation to an aggressive lymphoma. In addition, this rare case of transformation presented as a cavitary lesion.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, Henry Ford Hospital, Detroit, MI 48202, USA. rjvswarup@gmail.com.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Swarup