Pyoderma gangrenosum confused with congenital preauricular fistula infection: A case report.

BACKGROUND: Pyoderma gangrenosum resulting from or associated with congenital preauricular fistula is rarely reported. CASE SUMMARY: We report a rare case of pyoderma gangrenosum misdiagnosed as preauricular fistula infection. To our knowledge, this is the first report to describe pyoderma gangrenosum originating from the site of preauricular fistula. The lesion continued expanding even after combined treatment of systemic antibiotics and thorough debridement. Taking into account the possibility of pyoderma gangrenosum, we applied soft care with normal saline and Vaseline gauze dressing. Systemic corticosteroids were not used until intestinal Clostridium difficile was controlled. No local recurrence was noted at the 12-mo follow-up. CONCLUSION: This case highlights the necessity of considering rare diseases, such as pyoderma gangrenosum, when the preauricular sinus deteriorates with general management. The treatment strategy is mutually conflicting between pyoderma gangrenosum and infection of the preauricular sinus.