Pyoderma gangrenosum may precede, coexist or follow diverse systemic diseases. The bullous variety is usually associated with hematologic disorders. From 31 patients with pyoderma gangrenosum diagnosed in our hospital during 10 years, only 2 presented with the bullous type. One patient had previous diagnosis of chronic myeloid leukemia. Both had fast-progressive, painful lesions, and both showed an excellent response to systemic corticosteroids. In less than 3 months the lesions recurred simultaneously with the progression of chronic myeloid leukemia in one patient and with the initial diagnosis of acute myeloid leukemia in the other one. They died in less than four weeks. These findings emphasize the importance of its timely diagnosis. Cutaneous lesions could be the first predictor of an underlying disease.