[Distal cutaneous necrosis, an unusual etiology: hyperhomocysteinemia]

Homocysteine is a sulfur amino acid occurring in methionine intermediary metabolism. It was recently shown to be a vascular risk factor even without high serum levels.

A 29-year-old woman had painful plantar nodules and necrosis of the fifth toe on the right foot with cyanosis of the forefoot. The histology examination of a nodule biopsy gave the diagnosis of subcutaneous thrombophlebitis. Vascular explorations disclosed advanced-stage arteriopathy of the leg. The methionine loading test was abnormal and search for the heterozygous form of cystathionine ss was positive.

Different diagnoses could be possible for cases associating an inflammatory venous disease and stage IV arteritis. Latent hyperhomocysteinemia was diagnosed in this case on the basis of the methionine loading test and identification of the heterozygous form of cystathionine ss. Patients with latent hyperhomocysteinemia have an increased risk of both thrombosis and arteritis. Our case emphasizes the importance of searching for hyperhomocysteinemia in patients with early arterial and/or venous thromboembolism, either as repeated episodes or occurring in an unusual territory.