Differential Diagnosis for Right Achilles Painful to Touch and Swollen Ankle

Single Most Likely Diagnosis

• Achilles Tendinitis: This is the most likely diagnosis due to the location of the pain (Achilles tendon) and the symptoms described (painful to touch and swollen ankle). Achilles tendinitis is a common condition, especially in athletes or individuals who have recently increased their physical activity, causing inflammation of the tendon.

Other Likely Diagnoses

• Achilles Tendon Rupture: Although more severe, a rupture could present with sudden pain and swelling in the ankle area. It's less likely than tendinitis but should be considered, especially if there was a sudden onset of pain or a "pop" heard at the time of injury.
• Ankle Sprain: While the primary complaint is Achilles tendon pain, an ankle sprain could cause swelling and pain in the ankle area, potentially radiating to the Achilles tendon.
• Bursitis (Retrocalcaneal or Achilles Bursitis): Inflammation of the bursae near the Achilles tendon can cause pain, swelling, and tenderness in the area, similar to Achilles tendinitis.

Do Not Miss Diagnoses

• Deep Vein Thrombosis (DVT): Although less common, DVT can cause swelling and pain in the ankle and leg. It's crucial to consider this diagnosis due to its potential for severe complications, such as pulmonary embolism, if not promptly treated.
• Cellulitis or Infection: An infection in the soft tissues of the ankle could present with pain, swelling, and warmth. It's essential to identify and treat infections promptly to prevent serious complications.
• Fracture (e.g., Stress Fracture of the Calcaneus or Tibia): A fracture could cause pain and swelling in the ankle area. While less likely given the specific mention of Achilles tendon pain, it's a critical diagnosis not to miss due to the need for appropriate immobilization and potential surgical intervention.

Rare Diagnoses

• Seronegative Arthropathies (e.g., Psoriatic Arthritis, Reactive Arthritis): These conditions can cause inflammation and pain in the Achilles tendon and ankle but are less common than other diagnoses listed here.
• Tumors (e.g., Soft Tissue Sarcomas): Although extremely rare, tumors could cause swelling and pain in the ankle area. Given their rarity and the severity of the diagnosis, they are considered rare but should be kept in mind if other diagnoses are ruled out and symptoms persist or worsen.