[Pyoderma gangrenosum and hemopathies in older patients]

Pyoderma gangrenosum (PG) belongs to neutrophilic dermatoses. PG can have different clinical presentations (ulcerated, bullous, pustular), is often painful, and preferentially affects the lower limbs. The diagnosis can be challenging, and a cutaneous biopsy is often necessary, which shows an aseptic cutaneous infiltrate of neutrophils. The association with inflammatory or hematologic conditions is frequent, especially in older patients. The hematologic diseases the most frequently associated with PG are myelodysplastic syndrome, followed by monoclonal gammopathy of undetermined significance. Because of the strong impact of its treatment, recognition of PG is crucial. The treatment is based on first-line corticosteroids and topical or systemic immunosuppressive drugs and most often leads to a favourable outcome. The management of an acute hematologic disease would further improve the prognosis of PG. The singularity of geriatric patients encourages to thoroughly balance the risks and benefits of the recommended drugs and to consider associated non-drug measures. Here, we propose a review of the scientific literature about the association between PG and hematologic diseases, with a special focus on older patients, accompanied by the report of two cases in geriatric ward.