Toxic Oil Syndrome

Toxic oil syndrome is a rare intoxication, due to consumption of a rapeseed oil denatured with aniline 2%, characterized by generalized vascular lesions affecting all organs and vessels (including veins and arteries) and presenting with severe incapacitating myalgias, marked peripheral eosinophilia and pulmonary infiltrates.

Epidemiology

Spain is the only country to have reported cases of this disease in the spring of 1981 and patients resided in fourteen Central and North West provinces. Almost 20,000 people have been recorded, with women under the age of 40 years being more frequently and severely affected than men.

Clinical description

While TOS can affect all organs and vessels (such as the lungs, peripheral nerves, muscles, skin, digestive tract, liver and pancreas) the main outcome is fibrosis of the lumen of the vessels, skin, peripheral nerves and intestines. The disease course can be characterized by three clinical phases: i) the acute phase (lasting approximately 2 months) with a presentation of severe lung edema, eosinophilia, rash and myalgia, ii) the intermediate phase (2-3 months) with dysphagia, cramps, severe myalgia, skin edema, pulmonary hypertension, paresthesia, major vessel thromboembolism and severe weight loss, iii) the chronic phase, where the skin edema evolves to scleroderma, and the neuromuscular manifestations into paresis and paralysis due to polyneuropathy. Liver disease and fibrosis in major organs such as the pancreas and intestines are also present in patients with the poorest prognosis.

Etiology

The cause of TOS is the consumption of commercial rapeseed oil denatured with 2% of aniline. It was originally sold for industrial use and during the epidemic of 1981 was marketed fraudulently for human consumption. It still remains unclear whether fatty acid esters of 3-(N-phenylamino)-1, 2-propanediol (PAP) can induce TOS or if they are simply markers of oil toxicity.

Diagnostic methods

The diagnosis is based on clinical findings as there are no laboratory tests available.

Differential diagnosis

In the initial phase, several interstitial lung diseases should be excluded. Differential diagnoses for the chronic phase of TOS include several autoimmune rare diseases such as idiopathic pulmonary arterial hypertension, scleroderma (see these terms) and inflammatory polyneuropathy. Myalgia-eosinophilia syndrome associated with tryptophan (see this term) is another differential diagnosis that should be considered.

Management and treatment

No specific treatment is available. Major clinical features, such as lung edema at the earlier phase, can be treated with supportive measures at intensive care clinical units. Steroids are administered for some immunological manifestations, but they are not always effective. Certain major chronic features, such as pulmonary hypertension, are currently treated with modern vasodilators but many patients may require lung and cardiac transplantation. No effective treatments are available for scleroderma or neurological manifestations.

Prognosis

The prognosis is highly variable. Of the 20,000 people affected, more than 300 died during the first few years and around 30% of survivors developed a chronic condition. Other TOS survivors can show a variety of symptoms such as muscle pain, cramps and asthenia, as well as increased cardiovascular risks, while others have recovered with no further health problems.