[Acrodermatitis chronica atrophicans can be difficult to diagnose].

A healthy 29 year-old man developed over four years a slowly increasing swelling and violet discolouring of the third toe on his left foot. He was examined by several specialists and an amputation was recommended since the condition was unknown and aggravating. On suspicion of Borrelia infection the patient was prescribed penicillin treatment for 28 days with convincing effect. Serologic tests showed increased Borrelia titer. Biopsy showed chronic inflammation without any suspicion of malignity. Denmark is endemic for borreliosis and per year approximately 50 cases develop acrodermatitis chronic atrophicans.