Exogenous lipoid pneumonia (ELP) is a rare disease, caused when oily substances are aspirated and deposited in the alveoli.1

The most common radiological findings in ELP are ground glass opacities or peribronchial consolidations, mainly in the lower lung fields. Typical computed tomography (CT) findings include areas of fat attenuation, while on magnetic resonance imaging (MRI), the signal intensity for ELP in the various sequences is similar to that of fatty tissue. When accompanied by consistent clinical symptoms, these imaging study findings can determine a diagnosis of ELP.2

There are very few reports in the literature of ELP due to inhalation of lubricants used in cannula care in tracheotomy patients. We report 5 cases of ELP in patients with tracheotomy using Vaseline for the lubrication and insertion of cannulas.

Lipoid pneumonia is a rare disease, defined by the presence of intraalveolar lipids, classified as exogenous or endogenous.1–6

Exogenous lipoid pneumonia (ELP) is a very rare form of lipoid pneumonia caused by the aspiration of oily products (nostril lubricants, Vaseline, lip gloss, paraffin, etc.). It can be chronic, when associated with recurrent aspiration, or acute, when caused by the accidental aspiration of a large amount of oily substances.

From a clinical point of view, the chronic variant of ELP is often asymptomatic or presents with generalized symptoms. In our series, most patients were asymptomatic. The most common symptom was unproductive chronic cough (Table 1).

Chest CT findings in ELP have been described in several articles, the most common being consolidations and areas of peribronchial ground glass opacities, mainly in the lung bases.1,2,6 Attenuation of these consolidations is typically in the range of fatty tissue (−200 to −100HU). According to some authors,2 this finding, when accompanied by consistent clinical symptoms, may be sufficient for determining a diagnosis of lipoid pneumonia. Other less common radiological findings include crazy paving pattern (a linear pattern superimposed on a ground glass opacity) in the lung parenchyma, endobronchial secretions or unspecific areas of post-obstructive pneumonitis.7,8 In our series, the most common radiological finding was poorly defined opacities with areas of fat density on CT (Table 1).

As this entity can appear in the form of nodules or masses, differential ELP diagnosis must rule out malignancy. For this reason, some patients undergo complementary diagnostic tests such as PET/CT. ELP may be associated with unspecific increase in FDG uptake due to concomitant inflammatory changes, so morphological findings on CT must be taken into consideration when interpreting these examinations to avoid false positives.2,9,10

Although MRI is not a technique of choice for evaluating pulmonary parenchyma, it can be useful in the diagnosis of ELP, since it shows the fat content of lesions in T1-weighted sequences and signal suppression in fat suppression sequences (e.g., STIR).2 The second patient in our series refused bronchoscopy, so MRI was used to complete the assessment, and was found to be useful for confirming the fat content in the opacity seen on CT.

Proof of lipophages (vacuolated lipid-loaded macrophages) in sputum, transthoracic fine-needle aspirate, transbronchial biopsy and/or BAL is usually required for a definitive diagnosis of ELP, and the number of vacuolated alveolar macrophages generally correlates well with the severity of the disease.3,5 In other studies, BAL has been shown to be an effective treatment option, as it rinses the oily substances from the lung parenchyma, thus preventing the formation of fibrosis.

No other series with so many laryngectomy patients in a single hospital was identified, even after an exhaustive review of the literature. The 5 cases presented (Table 1) share the common factor of use of oily products (Vaseline) for the care and lubrication of tracheotomy cannulas. All cases shows fat attenuation images on CT, highly suggestive of lipoid pneumonia.

Radiological differential diagnoses of lesions with fat content include metastatic liposarcoma or hamartoma, although the radiological characteristics differ from those of ELP.10

When these cases of ELP were detected, we contacted the Tracheotomy Unit of the ENT Department of our hospital to discuss the findings and their relationship with the use of Vaseline as a lubricant for tracheotomy cannulas. On the basis of our clinical and radiological data, we recommended that, to avoid aspiration, liposoluble lubricants (such as Vaseline) should not be used for the daily care of the tracheal stoma in laryngectomy patients.

In our opinion, radiological findings (standard X-ray, CT, MRI and/or PET/CT) in patients with consistent clinical symptoms should provide sufficiently reliable data for determining a diagnosis of lipoid pneumonia. In some cases, radiological testing may be sufficient and invasive testing procedures can be avoided.