nformation sourced from BMJ:
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An unusual finger injury
David A Pettitt, Ashwin Pai, Emma Bradbury, et al.
Correspondence to: D A Pettitt firstname.lastname@example.org
A 39 year old female farmer with no medical history presented to the emergency department with a painless swelling over her right index finger. The problem started two weeks earlier after she had been bitten by a lamb. After the injury the finger appeared “bruised.” This bruising continued and a swelling gradually developed. She reported no pain, changes in sensation, or reduced range of movement.
On clinical examination she was afebrile and haemodynamically stable. Her right index finger exhibited a full range of movement and was neurovascularly intact. The finger was not tender on direct palpation and it seemed to be the same temperature as her other fingers. The finger had a laceration on the radial aspect proximal to the nail fold, with a demarcated and raised area of reddish-blue discoloration measuring about 2 cm × 1.5 cm. There was no palpable lymphadenopathy within the axilla.
Fig 1 Injured right index finger
1. What are the differential diagnoses?
Bruising (eg post-trauma), paronychia, herpetic whitlow, orf virus infection, Milker’s nodule, pyogenic granuloma, keratoacanthoma, and osteomyelitis.
2. What is the most likely diagnosis?
Orf virus infection is the most likely diagnosis because of the history of an animal bite followed by the appearance of a painless blue-black maculopapular lesion that does not affect range of movement.
3. What investigations might be ordered?
Orf infection is usually diagnosed clinically, but a finger radiograph and wound swab might rule out differential diagnoses. Diagnosis can be confirmed by electron microscopy or DNA polymerase chain reaction.
4. How is this condition managed?
Basic wound care, advice about hand hygiene, and discussion with plastic and reconstructive surgery specialists if there are concerns or complications.
This patient was discharged home after being reviewed by a senior plastic surgeon and being given a clinical diagnosis of orf infection. At review four weeks later in the outpatient plastic surgery clinic she had made a full recovery, with a full range of movement and no residual discoloration.