Mineral Oil: The Occult Cause of Critical Illness

A 59 year-old lady with a history of diabetes,
hypertension, and coronary artery disease presented to
the emergency department complaining of progressive
shortness of breath over a 6 month period. On initial
examination she was found to be hypoxemic with a
PaO² of 50 mmHg. A chest radiograph left lower lobe
consolidation (Figure 1). The patient was given broadspectrum
antibiotics and admitted to the intensive care
unit (ICU). In the ICU she remained on antibiotics
and bronchodilator therapy was started. Despite these
interventions, she showed no evidence of improvement
over next 48 hours.
Additional questioning revealed that the patient
had a history of chronic constipation for which she had
been using mineral oil as a laxative over the last decade.
A computed tomography (CT) scan of chest revealed
a large area of consolidation extending from the left
hilum into the left lower lobe with satellite nodules in
the left lower lobe (Figure 2). The patient underwent
bronchoscopy with bronchoalveolar lavage, which
showed mucin with intermixed degenerated epithelial
elements and focal foamy histiocytes. Transbronhcial
biopsies of the region yielded moderate patchy to
diffuse infi ltrate of multi-vacuolated histiocytes,
with occasional foreign body giant cells. The Sudan
black stain was positive. These fi ndings corroborated
a suspicion of lipoid pneumonia. Antibiotics were
stopped at that time. A follow up chest x-ray showed
improvement over 3 months with resolution of infi ltrate
over 6 months.
Lipoid pneumonia occurs mainly in children
and the elderly, who are at risk for aspiration. Because
of its high viscosity, mineral oil depresses the cough
refl exes, facilitating aspiration even in normal persons,
and patients with swallowing dysfunction are at an
increased risk. This condition can be underdiagnosed
as mineral oil is often not considered important by the
patient to be listed with the medications which they are
taking.