Metastatic squamous cell carcinoma of the ankle in long-standing untreated acrodermatitis chronica atrophicans.

Acrodermatitis chronica atrophicans (ACA) represents the persistent late stage of borreliosis in which Borrelia species may survive for decades. Occasionally, B-cell lymphoma may develop in these patients, and additional neoplastic complications such as basal cell carcinoma or squamous cell carcinoma (SCC) have been reported once each over the past 60 years. Here we describe, to the best of our knowledge, the first case of metastatic SCC in a European patient with long-standing ACA caused by Borrelia burgdorferi sensu stricto. Our case highlights a potential pathophysiological connection of untreated Borrelia infection with the initiation or progression of SCC and should alert dermatologists to this rare complication.