This site is intended for health professionals only

At the heart of general practice since 1960

Snapshot diagnosis - what's causing this painful reaction to cryotherapy?

Dr Mike Wyndham shares a case where liquid nitrogen therapy led to a painful reaction

Dr Mike Wyndham shares a case where liquid nitrogen therapy led to a painful reaction

The patient

This young man had received treatment in our minor surgery clinic for warts on the sole of his foot. He had a couple of blasts of liquid nitrogen to the affected areas and instructions to follow up with a standard anti-wart treatment.

Within a couple of days of cryotherapy, there was a marked painful blistering reaction. This slowly settled, but there still seemed to be a bigger skin problem.

First instinct

It all seemed rather strange. One of my dermatology teachers taught me that when warts are treated with cryotherapy, resolution was more likely if there was a blistering reaction. So why had things got worse?

Differential diagnosis

• Unresolved plantar warts

• Eccrine poroma

The hidden clue

An eccrine poroma is usually a raised lesion that causes an indentation of the surrounding skin. There did not appear to be any such indentation and this rather excluded that diagnosis. So warts seemed likely, particularly as the classic wart ‘black spots' were visible on the surface.

Getting on the right track

What struck me about the big lower lesion was that it had such a smooth round border. This was uncharacteristic of mosaic warts – or any clump of warts. Then the penny dropped – could this be a Koebner reaction? Although some authors1 consider that warts do not exhibit a Koebner reaction, they feel that spread occurs as a direct inoculation of the virus along a skin injury.


I reassured the patient that the problem was still warts. He certainly did not wish to have any further cryotherapy and was happy to continue with his topical salicylic acid.

Dr Mike Wyndham is a GP in Edgware, north London

Painful reaction after cryotherapy Painful reaction after cryotherapy

Rate this article 

Click to rate

  • 1 star out of 5
  • 2 stars out of 5
  • 3 stars out of 5
  • 4 stars out of 5
  • 5 stars out of 5

0 out of 5 stars

Have your say