Non Infectious Cavitary Exogenous Lipoid Pneumonia: A Case-Based Short Review

Lipoid pneumonia (LP) is due to the accumulation of either endogenous or exogenous lipids in the alveoli. The exogenous LP (ELP) results from the chronic aspiration or inhalation of animal, vegetable, or mineral oils or fatty substances that by reaching the pulmonary alveoli cause a foreign body-type inflammatory reaction of lung parenchyma, associated with fibrosis, necrosis, and possible cavitation. Pulmonary reaction is characterised by symptoms and radiological findings that are common to other pulmonary diseases. The radiologic presentation of ELP includes lung consolidations and ground-glass opacities, with predominant involvement of the lower lobes. Thickening of interlobular septa, adipose or not adipose single mass, and poorly marginated nodules may also occur. Cavitation, when present, is mainly associated with infection by non-tuberculous mycobacteria or fungi. Thus in patients exposed to lipoid aspiration presenting with cavitated mass on CT scan, possible infection should be thoroughly ascertained, and adequate treatment promptly initiated. Hereby, we report three cases of non-infectious cavitary exogenous lipoid pneumonia. In all three patients, one with acute onset and two with chronic recurrent form, the ELP diagnosis was confirmed by both cytological and histological findings, whereas microbiological examination gave negative results. Moving from these three cases, we review the pathogenesis, clinical and radiological manifestation of ELP.