Acenocoumarol-induced Henoch-Schönlein purpura

To report a probable case of Henoch-Schönlein purpura associated with acenocoumarol therapy.

A 76-year-old white woman was prescribed acenocoumarol for chronic atrial fibrillation. Two months after starting therapy, the patient came to our hospital's emergency department because of abdominal pain associated with vomiting. Physical examination revealed multiple round, confluent, purpuric lesions with some vesicles and an area of residual pigmentation. Lesions were present predominantly on the legs and gluteus, and also on the abdomen and arms. Skin biopsy of the lesions was compatible with leukocytoclastic vasculitis with deposition of immunoglobulin A. An upper intestinal endoscopy was done and identified purpuric mucosal lesions in the fundus, body, and antrum of the stomach and the duodenal bulb. Renal function was not affected, although proteinuria (1.26 g/day) was found and microscopic hematuria was observed.

The most likely cause of the Henoch-Schönlein purpura in this case was considered to be acenocoumarol because of the close temporal relationship between exposure to the drug and onset of symptoms, as well as the rapid resolution of the symptoms and signs after acenocoumarol was discontinued. The oral anticoagulant was the only identifiable precipitant that the patient encountered before the Henoch-Schönlein purpura developed. An objective causality assessment revealed that the adverse drug event was probable.

This case report illustrates a probable association between Henoch-Schönlein purpura and acenocoumarol. As of December 2003, this reaction had not been previously reported. Clinicians should be aware of this potential adverse effect of a widely used drug.