[Expanding papillomatous nodule on forearm with acute lymphangitis. Case of diagnosis].

Ecthyma contagiosum (orf) is a dermatosis commonly seen in those in contact with sheep. It is caused by Parapoxvirus ovis (orf virus), an oval epitheliotropic DNA parapox virus. The skin disease develops in stages starting as a macule or papule, becoming nodular, and then regressing. Diagnosis is based on history and histology, as well as identifying the virus through cell culture or specified polymerase chain reaction (PCR). The treatment of this self-limited disease is usually symptomatic.