Paraneoplastic Pyoderma Gangrenosum Associated with Rectal Adenocarcinoma

Pyoderma gangrenosum (PG) is a rare chronic neutrophilic dermatosis characterized by painful necrotic ulceration. The most common diseases associated with PG are inflammatory bowel disease, certain rheumatologic and hematologic diseases, and malignancy. Here, we describe the case of a 60-year-old man who presented with pruritic and painful erythematous ulcerative macules and patches on both lower extremities, and was diagnosed with PG based on his clinical and histologic features. His PG became exacerbated despite standard therapy with a high-dose systemic steroid in combination with dapsone and cyclosporine. Systemic evaluation of underlying conditions revealed rectal adenocarcinoma at the rectosigmoid junction (T3N0M0), which was completely removed via Hartmann's procedure followed by adjuvant chemotherapy. Two months after anticancer therapy, his PG was completely healed with hypertrophic scarring. Herein, we present the first case of paraneoplastic PG caused by rectal adenocarcinoma in Korea.