Bronchoalveolar lavage in the diagnosis of lipoid pneumonia

Lipoid pneumonia (LP) is an uncommon entity with the characteristic radiographic features and histologic findings of alveoli filled with vacuolated, lipid-laden histiocytes. We questioned whether bronchoalveolar lavage (BAL) could be useful in the confirmation of LP. We examined lipid stains (oil-red O) in BAL specimens from 18 cases, representing a variety of pulmonary disease states, and compared them with an index case of confirmed LP. The index case of LP had a history of chronic intranasal use of mentholated petrolatum with subsequent x-ray findings of progressive air bronchograms. Positive histochemical confirmation (oil-red O) performed on frozen sections of transbronchial lung biopsy was obtained. Eleven of the non-LP cases had no intracellular staining of BAL macrophages with oil-red O stain, whereas the index case of LP exhibited markedly positive intracytoplasmic staining of macrophages for lipid. The remaining seven cases showed minimal to mild lipid staining with only one other case having moderate staining. This study demonstrates that BAL macrophages from patients with a variety of pulmonary states and without suspected LP do not demonstrate significant staining for intracellular lipids, in contrast with the expected strong positivity of LP. Lipid staining of BAL specimens, although not entirely specific, may be a preferred method for confirming the diagnosis of LP, thereby avoiding more invasive procedures.