Abstract
Background. Pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma is relatively rare. Its diagnosis is determined by the pathological findings of pulmonary tissue, but there have been several cases in which it was difficult to distinguish MALT lymphoma from reactive lymphoid infiltration, because of the small size of biopsy tissue samples obtained by bronchoscopy. Case. A 64-year-old woman was referred to our hospital in 1996 because of an infiltrative shadow in the right upper lung field, on a chest X-ray film obtained at a routine health check. We performed bronchial mucosal biopsy of the upper right lobe by bronchoscopy in 2005. The pathological findings suggested pulmonary MALT lymphoma, but we could not confirm the diagnosis. In 2009, we applied the fluorescence in-situ hybridization (FISH) method to formalin-fixed bronchial tissue specimens obtained in 2005 after a new specimen treatment. Finally, the API2-MALT1 chimeric gene, characteristic of MALT lymphoma, was detected in a specimen and led to a confirmed diagnosis of pulmonary MALT lymphoma. Conclusions. The detection of the API2-MALT1 chimeric gene by FISH is now available, not only for frozen tissues, but also for tissue specimens fixed in formalin after re-treatment of the sample. This method was useful for retrospective studies of the API2-MALT1 chimeric gene in formalin-fixed tissue samples by FISH.
