Bullous Pyoderma Gangrenosum Associated with Hairy Cell Leukemia and Its Complete Response to Cladribine Therapy.

Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis seen in association with systemic disorders including hematologic malignancies. Hairy cell leukemia (HCL) however, is an unusual association of PG. We describe a 49-year old lady who presented to our hematology clinic with easy fatiguability and ulcerative skin lesions of 6 months duration. Examination revealed pallor and massive splenomegaly. Indurated, ulcerated lesion with undermined edges and necrotic base was observed on left thigh. Investigations revealed pancytopenia and bone marrow examination identified typical hairy cells. Flow cytometry of marrow aspirate was suggestive of classical HCL. BRAF V600E mutation was detected in peripheral blood by reverse transcriptase polymerase chain reaction. Skin biopsy revealed neutrophilic dermatosis and findings classical of bullous PG. Cladribine therapy (0.09 mg/kg/day by continuous intravenous infusion for 7 days) led to remission of both HCL and PG after a duration of 4 weeks. Cladribine monotherapy in a case of PG with HCL may avoid the additional immunosuppresion risk imposed by treating PG separately with corticosteroids. Immunosuppressive role of cladribine might be helpful in treating PG concurrent with HCL.