Differential Diagnosis for Acute Left Foot Swelling Non-Traumatic

Single Most Likely Diagnosis

• Cellulitis: This is a common cause of acute foot swelling, especially if it's non-traumatic. Cellulitis is a bacterial skin infection that can cause redness, swelling, and warmth in the affected area. The absence of trauma makes conditions like fractures or sprains less likely, pointing towards an infectious or inflammatory cause.

Other Likely Diagnoses

• Deep Vein Thrombosis (DVT): Although more commonly associated with the legs, DVT can cause swelling in one foot if the thrombosis occurs in the veins of the foot or lower leg. Risk factors such as recent travel, surgery, or immobilization increase the likelihood.
• Gout: An acute attack of gout can cause sudden swelling, redness, and pain in the foot, often starting in the big toe. It's a common condition that can be triggered by diet, alcohol, or certain medications.
• Lymphedema: If there's a history of surgery, infection, or trauma to the lymph nodes, lymphedema could be a cause of foot swelling. However, it typically presents more chronically.

Do Not Miss Diagnoses

• Compartment Syndrome: Although less common without trauma, compartment syndrome is a medical emergency that can occur due to increased pressure within the compartments of the foot. It requires immediate attention to prevent permanent damage.
• Septic Arthritis: An infection within a joint can cause acute swelling and is a medical emergency, especially if not promptly treated with antibiotics.
• Necrotizing Fasciitis: A severe infection that affects the tissue beneath the skin and the fascia, a layer of tissue covering muscles. It's rare but life-threatening and requires immediate surgical intervention.

Rare Diagnoses

• Erythromelalgia: A rare disorder characterized by burning pain, heat, and redness in the hands and feet, which can also cause swelling.
• Complex Regional Pain Syndrome (CRPS): A condition that can cause swelling, pain, and changes in skin temperature and color, usually after an injury or trauma, but can rarely occur without a clear precipitant.
• Kaposi's Sarcoma: A type of cancer that can cause swelling and lesions on the feet, more common in immunocompromised patients.

Each of these diagnoses has distinct features and risk factors that can help guide the diagnostic process. A thorough history, physical examination, and appropriate diagnostic tests are crucial for determining the underlying cause of acute non-traumatic foot swelling.