Severe Peripheral Arterial Ischemia Leading to Digital Gangrene in Mixed Connective Tissue Disease: A Case Report.

Mixed connective tissue disease (MCTD) is a rare systemic autoimmune disorder characterized by overlapping clinical features of systemic lupus erythematosus, systemic sclerosis, and polymyositis, in association with anti-U1 ribonucleoprotein (anti-U1-RNP) antibodies. Although vascular manifestations such as Raynaud's phenomenon are common, severe peripheral ischemic complications are rare. We report the case of a 40-year-old woman with known MCTD who presented with a three-month history of progressive necrotic lesions affecting the lower extremities, associated with severe pain, impaired ambulation, and ulcerative lesions of the hands. Her disease course was complicated by interstitial lung disease and pulmonary arterial hypertension. On admission, physical examination revealed extensive gangrenous lesions affecting multiple toes, along with cutaneous and musculoskeletal features consistent with advanced disease. Despite multidisciplinary management, the ischemic lesions progressed, and surgical intervention was planned. The patient subsequently developed sudden cardiorespiratory arrest and died before surgery. This report highlights a rare and severe vascular manifestation of MCTD characterized by peripheral arterial ischemia leading to digital gangrene. Clinicians should maintain a high index of suspicion for systemic autoimmune diseases in patients presenting with unexplained ischemic or necrotic lesions. Early recognition and multidisciplinary management are essential to improve clinical outcomes.