Comparison of exogenous and endogenous lipoid pneumonia: the relevance to bronchial anthracofibrosis

Lipoid pneumonia, caused by the accumulation of lipids in the alveoli, is classified into two forms (exogenous vs. endogenous) according to the source of the lipid exposure. There are no data directly comparing patients with exogenous and endogenous lipoid pneumonia. All patients who were diagnosed with lipoid pneumonia between January 2008 and December 2016 at Kyungpook National University Hospital, a tertiary referral hospital in South Korea, were retrospectively reviewed. The clinical, radiologic, and bronchoscopic findings for the two forms of lipoid pneumonia were compared. A total of 13 patients who met the criteria for a confirmed diagnosis of lipoid pneumonia were included. Dyspnea at presentation, predominant lower lobes involvement, bronchial anthracofibrosis (BAF), and recurrent episodes were more frequent in patients with the endogenous form than in those with the exogenous form. Of them, a notable finding was that BAF was identified in all five patients with the endogenous form, whereas BAF was observed in only one of the eight patients with the exogenous form (P=0.005). This finding suggests that BAF may be associated with endogenous form. Awareness of this association between endogenous lipoid pneumonia and BAF may help clinicians avoid delaying diagnoses.