Liquid silicone (polydimethylsiloxane) is a highly stable synthetic polymer,
which has poor immunogenicity,
minimal tissue reaction,
few changes in physical characteristics with temperature and age,
and is not carcinogenic,
commonly used for medical and cosmetic purposes,
the latter associated with serious complications.
Common sites of illicit subcutaneous injection of silicone that have been reported are the breasts,
the trochanteric region,
and the buttocks [1].
Complications associated with illicit injection occur with an incidence rate of up to 1-2%,
[1] including local effects such as tissue necrosis,
foreign body reactions and infection.
Complications in distant organs suggest an embolic phenomenon that manifests as regional lymphadenopathy,
granulomatous hepatitis,
interstitial nephritis and other acute systemic diseases [3],
but the pulmonary and neurological sequelae are the most serious and those that generate higher mortality [2].
Symptoms usually appear in the first 72 hours after the injection [2,6],
and among the most common are hypoxia (92%),
dyspnea (88%),
fever (70%),
alveolar hemorrhage (64 %) and cough (52%) [4],
in some cases there may be hemoptysis [2,6,10].
The clinical presentation,
pathophysiology and outcome are similar to fat embolism [1,10].
The histopathological findings in the pulmonary parenchyma that have been reported include the presence of intravascular silicone vacuoles,
edema and extensive hemorrhage; acute pneumonitis and alveolitis with focal thickening: increase in the number of macrophages,
neutrophils and eosinophils; and diffuse alveolar damage [2,3].
Regarding imaging findings,
peripherally distributed ground-glass opacities have been consistently demonstrated,
occasionally accompanied of airspace consolidation,
being found in both plain radiography and computed tomography (CT) [1,2].
Restrepo et al.
(2009) conducted a review on the imaging findings in a series of 10 patients with clinical syndrome of pulmonary embolism due to illicit injection of liquid silicone,
where the most distinctive findings were peripheral ground glass opacities and consolidation,
commonly associated with interlobular thickening visualized in CT,
similar to the image pattern mentioned in previously reported cases; in no case was pleural fluid demonstrated [1].
There are several risk factors for developing silicone pulmonary embolism such as the inadvertent injection directly into a vein [2],
the injection of large volumes and massages or trauma after the procedure [1].
The differential diagnosis includes some eosinophilic pulmonary disease like simple pulmonary eosinophilia or Loeffler's syndrome,
chronic eosinophilic pneumonia and eosinophilic pneumonia induced by drugs and fat embolism syndrome [6].
Treatment involves supportive measures,
which may include invasive mechanical ventilation.
In some cases steroids have been used with uncertain utility [2].
With these measures,
a favorable evolution can be observed,
although a high mortality rate (20%) has been demonstrated in previous studies [1].