Pyoderma gangrenosum and underlying diseases in Japanese patients: A regional long-term study

Pyoderma gangrenosum (PG) is a chronic inflammatory disease of unknown cause that presents as an inflammatory and ulcerative disorder of the skin. PG is often associated with an underlying systemic disease. However, the frequencies of the underlying diseases are unclear in Japanese patients. In this retrospective, observational study, all patients diagnosed with PG who visited dermatology departments of nine regional hospitals in and around Ibaraki Prefecture were collected from 1982 to 2011 or 2014. The diagnoses of PG were based on the characteristic clinical and histological appearances and ruling out of infection. Sixty-two PG patients, including 29 males and 33 females, were identified. The ages of onset were 16-89 years, and the mean age was 50.2 years. Fifty (80%) of the 62 patients presented with an ulcerative PG, and the lower leg was the most common site (74%). Forty-six (74%) PG patients had underlying diseases. The most frequent was ulcerative colitis (32%), followed by myelodysplastic syndrome (11%), rheumatoid arthritis (6%) and aortitis syndrome (5%). For treatment, 54 cases (87%) received systemic corticosteroids and 10 received additional treatment with cyclosporin. There was no significant correlation between underlying diseases and response to the initial treatment. Multivariate analysis revealed that the number of affected sites negatively correlated with successful initial treatment. Fifteen (24%) of the 62 cases relapsed. In conclusion, ulcerative colitis and hematological disorders were frequently associated with PG while approximately a quarter of the cases were idiopathic.