Differential Diagnosis for Right Lower Extremity Pain, Swelling, and Redness
Single Most Likely Diagnosis
- Cellulitis: Given the patient's symptoms of pain, swelling, and redness in the right lower extremity, cellulitis is a strong consideration. The absence of a fracture and a normal DVT ultrasound, combined with the clinical presentation, points towards a soft tissue infection.
Other Likely Diagnoses
- Deep Vein Thrombosis (DVT): Although the previous DVT ultrasound was normal, the initial elevated D-dimer and the persistence of symptoms could suggest a new or missed DVT. The current D-dimer is slightly elevated, which, although not diagnostic, warrants consideration.
- Muscle Strain or Contusion: Given the history of a fall, a muscle strain or contusion could be causing the ongoing pain and swelling, especially if the initial injury was not fully assessed or if there was a delay in the onset of symptoms.
- Chronic Venous Insufficiency: This condition could lead to swelling and skin changes in the lower extremities, especially if the patient has a history of DVT or other venous issues.
Do Not Miss Diagnoses
- Osteomyelitis: Although the X-ray did not show a fracture, osteomyelitis (bone infection) could be a consideration, especially if the patient has a history of diabetes, immunocompromised status, or if the fall caused a occult fracture not visible on initial X-ray.
- Compartment Syndrome: This is a medical emergency that could occur after a fall, especially if there was significant trauma. It presents with pain, swelling, and sometimes pallor or paresthesia.
- Arterial Occlusion: Decreased blood flow to the lower extremity could cause pain, swelling, and changes in skin color. This is a medical emergency requiring prompt intervention.
Rare Diagnoses
- Erythema Nodosum: An inflammatory condition that could cause redness and swelling, typically on the lower legs. It's often associated with other systemic conditions or infections.
- Lymphedema: Swelling due to lymphatic obstruction, which could be primary or secondary to another condition. It's less likely given the acute presentation but could be considered if other diagnoses are ruled out.
- Panniculitis: Inflammation of the subcutaneous fat, which could cause pain, swelling, and skin changes. It's a rare condition with various causes, including autoimmune diseases and infections.