Diagnosis: Levamisole toxicity
The patient was diagnosed with levamisole toxicity based on his clinical presentation and the fact that he had used cocaine around the time his ear lesions appeared.
Levamisole—primarily a veterinary antihelmintic medication—is used on rare occasions to treat nephrotic syndrome in children.1 Levamisole is frequently added to cocaine or heroin to increase the street drug’s potency. The Drug Enforcement Administration reports that 69% of seized cocaine lots in the United States contain levamisole.2
The compound is thought to cause a vasculitis and bone marrow suppression resulting in neutropenia. The vasculitis targets small vessels, resulting in thrombosis, which can lead to tissue necrosis.1
Other possibilities in the differential Dx
The differential diagnosis includes a variety of vasculitides and other microvascular pathologies.
Cholesterol emboli arise when cholesterol crystals are released from atherosclerotic plaques, typically after invasive cardiac procedures. In addition, anticoagulants can cause the release of these crystals by inhibiting the formation of protective clots around unstable plaques.3 These emboli can seed the microvasculature anywhere, but the kidneys and skin are most frequently affected. These crystals not only clog the vasculature, causing tissue ischemia, but also activate the complement cascade, triggering a series of inflammatory responses that can lead to luminal fibrosis and narrowing.3
Affected patients have a history of atherosclerotic disease or predisposing factors such as hypertension or diabetes. Ulcerations or frank cyanosis may be found at the tips of the fingers or toes. In severe cases, gangrene will form in these regions. Patients may also have livido reticularis, a lace-like hyperpigmented rash over the lower extremities. Laboratory analysis may indicate acute renal failure or eosinophilia.3