OBJECTIVE: To outline the characteristics of deep dissecting hematoma (DDH). DESIGN: Retrospective medical record review. SETTING: Department of Dermatology, University Hospital of Geneva, Geneva, Switzerland. PATIENTS: Thirty-four patients with DDH. INTERVENTIONS: Deep incision or surgical debridement was performed in all the patients. Direct closure of the incision was possible in 6 patients, and split-thickness skin grafting was applied to 17 patients. MAIN OUTCOME MEASURES: Sex of the patient, the affected area, presence of dermatoporosis, presence of systemic treatment, initial and late symptoms, anatomic location of DDH, and the mean length of hospital stay. RESULTS: Most frequently, elderly women were affected (mean age, 81.7 years); women outnumbered men by a ratio of 5:1. In all the patients, the leg was the affected part of the body. All the patients, except for the 2 youngest ones, had advanced dermatoporosis, and the most severe form was seen in the older patients who were receiving long-term treatment with systemic corticosteroids. Half of the patients were receiving anticoagulation drugs. The initial symptoms in all the patients were pain and swelling of the leg. Erythema and edema without fever were observed. Skin necrosis developed as a late manifestation. Erysipelas was the initial diagnosis in up to 14 patients who had been treated with antibiotics before admission. The mean delay before hospital referral was 16.4 days. Magnetic resonance imaging and histopathological analysis confirmed deep anatomical location of DDH. Hospital treatment consisted mainly of deep incision and debridement followed by direct closure, skin grafting, or wound healing per secundam. The mean length of hospital stay was 3.5 weeks. CONCLUSIONS: Deep dissecting hematoma is an emerging clinical entity and a major complication of dermatoporosis. Prompt diagnosis and treatment is a major factor for the prognosis. Health care professionals, especially general practitioners, should be aware of the symptoms and signs of this condition as well as the risk factors involved. Given the high cost of treatment, in addition to the inconvenience it causes for the patient, preventive measures should be implemented early.