Catastrophic antiphospholipid syndrome (CAPS) is a rare and fatal condition that is characterized by diffuse venous and/or arterial thromboembolism within a short period of time and histopathological confirmation of small-vessel occlusion in at least one organ or tissue in the presence of positive antiphospholipid antibodies. Here we report the case of a 19-year-old woman with CAPS. During the first week of her hospitalization, she was diagnosed with CAPS on the basis of skin necrosis, pulmonary artery thrombosis, cerebral venous sinus thrombosis, and positive lupus anticoagulant. She was treated with corticosteroids, intravenous immunoglobulins, plasmapheresis, and anticoagulants. Forty days after the onset of CAPS, cutaneous lesions were recurred during skin surgery. She required a high dose of corticosteroids, intravenous immunoglobulins, and rituximab. No further thrombotic events occurred. Rituximab may be an effective treatment option for patients with CAPS.