Differential Diagnosis for Unilateral Limb Swelling

The presentation of unilateral limb swelling, specifically in the upper and lower right limbs, suggests a variety of potential causes. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis
  • Lymphedema: This condition, characterized by the abnormal accumulation of protein-rich fluid in the interstitial tissue, can be primary (inherited) or secondary (acquired) due to surgery, infection, or trauma. Unilateral presentation is common, especially if the cause is localized, such as after lymph node removal or radiation therapy for cancer.
• Other Likely Diagnoses
  • Deep Vein Thrombosis (DVT): Although DVT typically presents with unilateral swelling, it usually involves one limb at a time. However, it's conceivable for DVT to occur in both the upper and lower limb on the same side, especially in the context of a hypercoagulable state or a central venous catheter.
  • Infection or Cellulitis: Unilateral swelling can be a sign of a localized infection, which could involve both an upper and lower limb if the infection spreads or if there are multiple sites of infection.
  • Trauma: Direct injury to the limbs could result in swelling due to inflammation, hematoma, or compartment syndrome.
• Do Not Miss Diagnoses
  • Superior Vena Cava Syndrome: Although rare, this condition, characterized by obstruction of the superior vena cava, can cause swelling of the upper limb, face, and possibly lower limb if the inferior vena cava is also affected or if there's significant collateral circulation.
  • Malignancy: Certain cancers can cause unilateral limb swelling, either by direct invasion of lymph nodes and vessels or through metastasis. It's crucial not to miss a potential malignancy, as early diagnosis significantly impacts prognosis.
• Rare Diagnoses
  • Klippel-Trenaunay Syndrome: A congenital condition characterized by vascular malformations, which can lead to unilateral limb swelling, varicose veins, and port-wine stains.
  • Parkes Weber Syndrome: Similar to Klippel-Trenaunay, but with the addition of arteriovenous fistulas, leading to increased blood flow and swelling in the affected limb.
  • Lipedema: A chronic condition characterized by the abnormal growth of fat cells in the legs, leading to swelling, pain, and bruising. It can be unilateral and may involve both the upper and lower limbs, though this is less common.

Each diagnosis has a unique set of clinical features, and a thorough history, physical examination, and diagnostic tests (such as imaging studies and blood work) are essential for determining the underlying cause of the unilateral limb swelling.