Download Pyoderma Gangrenosum in a renal transplant recipient?

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PYODERMA GANGRENOSUM IN A RENAL TRANSPLANT RECIPIENT? A CASE
OF MISTAKEN IDENTITY UNDERLINING THE IMPORTANCE OF A SKIN BIOPSY
IN SUCH CIRCUMSTANCES
Standen, P.S.1, Thandi, C.S.2 and Murray, J.S.3
1
Core Trainee and 3Renal Consultant, Department of Renal Medicine, James Cook
University Hospital, Middlesbrough, 2Medical Student, Newcastle-Upon-Tyne University,
Newcastle
Case History.A sixty four year old renal transplant recipient who had recently been treated
for cytomegalovirus disease, was promptly referred for dermatological opinion after a 10mm
bluish-edged ulcer was noted on his right calf. Assessment in the dermatology clinic
precipitated a clinical diagnosis of pyoderma gangrenosum. Of note it was deemed that skin
biopsy was contraindicated due to the risk of pathergy associated with pyoderma
gangrenosum. The lesion was subsequently treated aspyoderma gangrenosumduring regular
follow up in the dermatology clinic, initially with topical steroids and then with an increase in
oral steroid dose. Although the lesion did not evolve further at that stage, it did not regress
despiteprolonged high-dose steroid therapy; on-going treatment failure and overgranulationlater culminated in a skin biopsy being reconsidered and performed, primarily to
exclude malignancy. Of note tissue assessment for fungal infection was not undertaken at
that time. The clinical picture worsened despite a further eight months of regular
dermatological review and steroid therapy; the initial ulcer began to enlarge and the patient
also developed a haemorrhagic nodular satellite lesion on his left elbow and further multiple
satellite nodules and areas of skin breakdown on his leg. One of the satellite lesions was then
biopsied and crucially on this occasion the tissue was sent for culture and this revealed
Alternaria infectoria. Both this satellite lesion biopsy and the previousindex ulcer biopsy
(from eight months previous) were then retrospectively stained to specifically assess for
fungal elements; both were positive for fungal infection. Although the immediate
introduction of anti-fungal therapy (liposomal Amphotericin B) at that stage led to some
dermatological improvement, the patient’s overall condition had significantly deteriorated;
chest imaging and bronchoscopy confirmed disseminated fungal and associated superinfections and the patient died despite anti-microbial tailored therapy and cessation of
immunosuppression.
Discussion. This case highlights the importance of retaining a low threshold for attaining
histological diagnoses in transplant recipients whom develop new or evolving cutaneous
lesions. The clinical diagnosis of pyoderma gangrenosum in the case presented illustrates
this point well; although the appearances of the initial lesion were considered diagnostic
ofpyoderma gangrenosum during repeated assessment in the dermatology clinic,
comorbidities associated with pyoderma gangrenosum were absent and notably the patient
was already taking medication used to treat pyoderma gangrenosum (steroids and calcineurin
inhibitors) at the onset of his index skin lesion. Meticulous assessment of cutaneous lesions
in transplant recipients should extend beyond ruling out malignant disease and seek also to
promptly exclude the presence of opportunistic infection. Alternaria species, a group of
ubiquitous environmental fungi, have been reported to cause opportunistic infection in
immunocompromised hosts and this case illustrates the importance of overcoming diagnostic
challenges posed by such uncommon pathogens, in order to avoid diagnostic delaysin such
circumstances.