Pyoderma gangrenosum following trauma of the knee: a case of pathergy and review of orthopaedic cases.

Pyoderma gangrenosum (PG) is a rare noninfectious neutrophilic dermatosis. Its course can be mild or malignant, chronic or relapsing with remarkable morbidity. We describe a case of PG, which presented with severe wound breakdown following a closed tibial plateau fracture of the left knee. Two weeks after the trauma, the patient developed ulcers in both lower legs. Sepsis was suspected and concomitant treatment was begun. No causal agent was found. A suspicion of PG arose and a treatment with corticosteroids was started. The patient recovered swiftly. The very rare pathology of PG is discussed and a review of the literature of this pathology is given. This diagnosis should always be considered when confronted with an enlarging painful skin lesion, which does not grow organisms when cultured and fails to respond to antibiotic therapy, especially if there are similar lesions in other sites. To our knowledge, this is the first case report of PG following trauma without any skin lesions at initial trauma.