Evaluation of Lipoid Pneumonia

¹ Department of Pathology, Mercy Hospital. Now at San Luis Obispo, California.

In this study lipoid pneumonias are classified as (1) exogenous, manifested by paraffinomas or oil granulomas due to aspiration of mineral, vegetable, or animal oils; and (2) endogenous (cholesterol pneumonitis, Wegener's granuloma, etc.).

Nine cases of lipoid granuloma treated surgically in the past 10 years were reviewed in the light of new etiological factors. All had been previously classified as oil granulomas or paraffinomas. Indeed, the gross appearance of the lesions in both types may look alike to the casual observer. However, histological studies revealed that five of our cases should be classified as endogenous, rather than exogenous, lipoid pneumonia.

The source of exogenous lipids is obvious; the cause of cholesterol deposits is harder to evaluate and possible reasons for the presence of cholesterol are discussed. It seems likely that many cholesterol granulomas are absorbed spontaneously and only those lesions persist that have met with severe desmoplastic reaction. These may require thorocotomy if extensive cavitation occurs.

Those lesions of an exogenous nature may be diagnosed by repeated sputum analyses and special stains, supported by history of the use of oils. Treatment consists of discontinuing the use of the offending oil and rarely is surgical removal necessary.