Multiple Pyoderma Gangrenosum Overlying AV Fistula Treated With Colchicine: A Case Report.

Rationale: Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis which gives rise to painful ulcers. Pyoderma gangrenosum can be triggered by trauma, a phenomenon called pathergy. Here, we report the first case of PG arising from pathergy due to needle insertion overlying an arteriovenous fistula (AVF). This case report seeks to inform nephrologists about PG, this yet unreported presentation, and management in the context of hemodialysis. Presenting concerns: A 69-year-old woman presented to dermatology clinic for erythemato-violaceous plaques with central ulceration at the site of needle insertion overlying her AVF. The patient was known for chronic renal insufficiency secondary to C3 glomerulonephritis, for which she received hemodialysis. After an accidental burn which lead to appearance of a painful ulcer, following each needle insertion for hemodialysis, she would develop an erythematous papule that progressed to a painful ulcer with erythematous-violaceous borders. Diagnosis: Pyoderma gangrenosum was clinically diagnosed and both clinical and paraclinical evaluation did not reveal any secondary cause of PG. Intervention: Dialysis via AVF was suspended due to the risk of triggering more PG and was temporarily pursued by central venous catheter. The patient was initially treated with prednisone and topical corticosteroids. Furthermore, owing to the high recurrence rate of PG, colchicine was initiated in prevention to avoid resorting to immunosuppressive or long-term corticotherapy. Outcomes: The patient's lesions improved on prednisone, which was then tapered over 1 month. Following prednisone taper and continuing improvement of PG on colchicine and topical corticosteroids alone, the decision was taken to recommence dialysis via AVF after performing a negative pathergy test. Topical corticosteroids were ceased due to the risk of cutaneous atrophy and were replaced by pimecrolimus ointment. The patient has continued dialysis via AVF ever since, without recurrence. Novel Finding: This is the first case reported of PG arising from pathergy due to needle insertion overlying an AVF. Colchicine may be a safe and effective therapy for long-term treatment of PG in the context of hemodialysis.