Differential Diagnosis for Unilateral Lateral Leg Swelling
Single Most Likely Diagnosis
- Cellulitis: This is often the most common cause of unilateral leg swelling, characterized by redness, warmth, swelling, and sometimes fever. It's a bacterial infection of the skin and subcutaneous tissues, usually caused by Streptococcus or Staphylococcus species.
Other Likely Diagnoses
- Deep Vein Thrombosis (DVT): A blood clot in the deep veins of the leg can cause swelling, pain, and discoloration. Risk factors include recent surgery, immobilization, cancer, and genetic predispositions.
- Lymphedema: This condition involves the abnormal collection of protein-rich fluid in the interstitial tissue, leading to swelling of one or more extremities. It can be primary (genetic) or secondary (due to surgery, infection, or trauma).
- Venous Insufficiency: Weakened or damaged veins can lead to poor blood circulation, causing fluid buildup and swelling in the legs.
Do Not Miss Diagnoses
- Compartment Syndrome: A medical emergency where increased pressure within a muscle compartment leads to inadequate blood supply to the tissues inside the compartment. It can cause severe pain, swelling, and potentially permanent damage if not promptly treated.
- Necrotizing Fasciitis: A severe infection of the fascia, the tissue that covers muscles, nerves, fat, and blood vessels in the affected area. It's characterized by rapid progression, severe pain, and can be life-threatening if not treated promptly.
- Phlegmasia Cerulea Dolens: A severe form of DVT that causes significant swelling and cyanosis (blue discoloration) of the leg due to near-total occlusion of the venous system.
Rare Diagnoses
- Lipedema: A chronic condition characterized by the abnormal growth of fat cells in the legs, leading to swelling and pain. It's often mistaken for lymphedema but does not typically involve the feet.
- Erythema Nodosum: An inflammatory condition that causes red, painful nodules under the skin, often on the shins. It can be associated with various underlying conditions, including infections, medications, and systemic diseases.
- Klippel-Trenaunay Syndrome: A rare congenital condition characterized by abnormal development of blood vessels, soft tissue, and bone, leading to swelling, varicose veins, and other vascular anomalies in the affected limb.