Differential Diagnosis for Unilateral Leg Pain and Swelling

Given the symptoms of unilateral pain in the leg, swelling in the heels that is mon tender and hard, along with the laboratory tests already conducted (HB, ESR, CRP, and uric acid), the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Gout: The presence of unilateral pain and swelling, particularly if it's localized to the heel (which could imply involvement of the Achilles tendon or the surrounding area), along with elevated uric acid levels, makes gout a strong consideration. Gout is known for causing sudden, severe attacks of pain, swelling, redness, and tenderness in one or more joints, most often in the big toe but can occur in the heel.

• Other Likely Diagnoses

  • Cellulitis: An infection of the skin and subcutaneous tissues that can cause pain, swelling, and tenderness. It's usually accompanied by redness and warmth of the affected area.
  • Deep Vein Thrombosis (DVT): Although DVT typically presents with swelling, warmth, and discoloration of the affected limb, it can sometimes cause pain and tenderness, especially if it's extensive or if there's associated inflammation.
  • Peripheral Artery Disease (PAD): PAD can cause intermittent claudication, which is pain in the legs or buttocks during exercise, but in severe cases, it can lead to chronic pain at rest and tissue loss.

• Do Not Miss Diagnoses

  • Osteomyelitis: An infection of the bone that can cause pain, swelling, and tenderness. It's a serious condition that requires prompt treatment to prevent long-term damage.
  • Erythema Nodosum: A condition characterized by the sudden formation of painful nodules under the skin, typically on the shins. It can be associated with various underlying conditions, including infections, autoimmune disorders, and medications.
  • Compartment Syndrome: A condition where pressure within the muscles builds to dangerous levels, decreasing blood flow and potentially leading to nerve and muscle damage. It's a medical emergency.

• Rare Diagnoses

  • Paget's Disease of Bone: A chronic condition that can result in enlarged and misshapen bones due to abnormal bone destruction and regrowth. It can cause bone pain and deformities.
  • Eosinophilic Fasciitis: A rare condition characterized by inflammation of the fascia (the tissue surrounding muscles), which can cause pain, swelling, and skin thickening.

Additional Investigations

• Imaging Studies: X-rays to evaluate bone integrity and structure, ultrasound to assess for DVT or vascular issues, and possibly an MRI for detailed evaluation of soft tissues, bones, and potential infections.
• Blood Cultures: If there's suspicion of an infectious process like osteomyelitis.
• Autoimmune Panels: If there's a suspicion of an underlying autoimmune condition that could be contributing to the symptoms.
• Nerve Conduction Studies (NCS) and Electromyography (EMG): If there's concern for nerve involvement or compartment syndrome.
• Biopsy: In cases where a specific diagnosis like eosinophilic fasciitis or Paget's disease is considered, or to rule out malignancy.