Unusual case of extracutaneous pyoderma gangrenosum with myelodysplastic syndrome.

Pyoderma gangrenosum (PG) is a rare, noninfectious, inflammatory disease characterized by neutrophilic infiltration and destruction of tissue. Extracutaneous involvement in PG is unusual. Myelodysplastic syndrome (MDS) is the most frequent hematologic disease associated with PG. We present a case diagnosed with MDS-EB-I. He had a large ulcer in his buttocks. Tissue culture and microscopy showed no evidence of fungi, bacteria, or mycobacteria. Histology showed granulation tissue, inflammatory infiltrate, abscess formation, and focal necrotizing vasculitis. Dermatology opinion confirmed PG. The skin lesions responded well to corticosteroid treatment at first, but it relapsed quickly with involvement of skin and lungs. In the meantime, MDS progressed to acute myeloid leukemia. The patient received chemotherapy and immunosuppressive therapy at the same time. After achievement of complete remission (CR), he had allogeneic hematopoietic stem cell transplantation. Two years later, the patient is still in CR status with no sign of PG relapse.