Case Number : Case 2009 - 16 Feb 2018 Posted By: Dr. Richard Carr

The salient features are pseudoepitheliomatous hyperplasia and suppurative granulomatous inflammation. The 'odd' look suggests that it could be blastomycosis-like pyoderma. Other differentials are of course deep fungal infection, atypical mycobacterial infection, halogenoderma and superficial granulomatous pyoderma gangrenosum. Culture from the discharge, PAS stain and Fite Faraco for AFB may clarify further

Vegetative pyoderma gangrenosum was my first spot. 

Further information: Site is leg. Additional history information. On long term steroids for Crohn's disease.

Pyoderma gangrenosum

Found this interesting art. https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwiWoq_66LHZAhUFbVAKHUI5D6EQFggtMAA&url=https%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fpmc%2Farticles%2FPMC5347515%2F&usg=AOvVaw1HwTL88HfqskAe-_jNc8Lj.

Vedolizumab treatment?

Mycobacterium chalonae/abscessus infection likely as the patient is immunocompromised.

Yes you nailed it. M. Chelonae on culture. The original reporting pathologist did not see the suppurative granulomatous aspect and did not do special stains. I was asked to review it following positive culture. Remember the histopathology of so-called superficial granulomatous pyoderma (pyoderma gangrenosum variant) can look histologically similar but would not generally be favoured when you know the patient is on steroids already!

Lovely!