Orf (ecthyma contagiosum) is caused by a parapox virus that can be transmitted to those handling infected sheep or goats. The most common presentation is a circumscribed solitary nodule or papule on the fingers or hands. Diagnosis is usually simple if contact with sheep is recognized. During a period of approximately 6 weeks, the lesions pass through six clinical stages, each lasting about 1 week:
- Maculopapular stage
- Target stage, during which the lesions have red centers, white rings, and red halos
- Acute weeping stage
- Nodular stage, which shows hard, non-tender nodules
- Papillomatous stage (nodules have irregular surfaces)
- Regressive stage (the lesions involute without scarring)
The current case is a middle-aged house wife presented with a single painful erythematous nodule on the radial side of the base of the left index finger. The lesion has appeared 5 days after sheep handling (sheep’s head cooking) as a small papule that transformed into a hard nodule with central pustulation within a few days. The nodule has typical target appearance.