Secondary organizing pneumonia associated with pulmonary tuberculosis: case series and review of the literature

Abstract Background: Secondary organizing pneumonia (SOP) is difficult to distinguish from cryptogenic organizing pneumonia (COP) considering various clinical situations. SOP caused by Mycobacterium tuberculosis is rare; indeed, it has not been reported as a sequela of disseminated tuberculosis.Methods: From January 2016 to December 2018, we identified six cases of tuberculosis-associated SOP in which Mycobacterium tuberculosis was revealed by microbiological examination; one of the cases was miliary tuberculosis.Results: Of the six cases, 17% were positive for acid fast bacillus (AFB) stain, but 100% were positive for M. tuberculosis polymerase chain reaction (MTB PCR) and AFB culture. In all cases, transbronchial lung biopsy was performed and organizing pneumonia was confirmed pathologically. All survived after treatment with anti-tuberculosis therapy.Conclusions: Even if a biopsy performed in cases with pneumonia showing slow improvement appears to suggest organizing pneumonia, the possibility of tuberculosis should always be kept in mind in areas with high tuberculosis prevalence. MTB PCR appears to be more helpful than AFB stain for the first diagnosis of SOP associated with pulmonary tuberculosis.