Differential Diagnosis for Left Lower Extremity Swelling and Pain

Single Most Likely Diagnosis

• Diabetic Foot Syndrome: Given the patient's new onset diabetes, neuropathy in both feet, and the presence of bony deformities on X-ray, diabetic foot syndrome is a strong consideration. The swelling, warmth, and pain in the left lower extremity could be indicative of an infectious or inflammatory process common in diabetic patients.

Other Likely Diagnoses

• Cellulitis: The symptoms of swelling, warmth, and pain, especially in the context of diabetes and potential neuropathy, could suggest cellulitis, a bacterial skin infection.
• Deep Vein Thrombosis (DVT) Residual or Missed: Although an ultrasound was performed to rule out clots, the possibility of a missed DVT or residual effects from a previous DVT cannot be entirely excluded without further diagnostic confirmation.
• Osteomyelitis: Given the bony deformities and the patient's diabetic status, osteomyelitis (bone infection) is a plausible diagnosis, especially if there's a history of foot ulcers or trauma.

Do Not Miss Diagnoses

• Septic Arthritis: Although less common, septic arthritis is a serious condition that requires prompt diagnosis and treatment. The presence of significant pain, swelling, and warmth, along with systemic symptoms like fever (if present), could indicate septic arthritis.
• Necrotizing Fasciitis: This is a life-threatening condition that could present with severe pain, swelling, and skin changes. Early recognition is crucial for survival.
• Compartment Syndrome: This condition, characterized by increased pressure within a muscle compartment, can lead to severe pain, swelling, and potentially permanent damage if not promptly addressed.

Rare Diagnoses

• Erythromelalgia: A rare disorder characterized by burning pain, heat, and redness in the hands and feet, which could be considered in the differential given the patient's symptoms of warmth and pain in the left lower extremity.
• Complex Regional Pain Syndrome (CRPS): Although rare, CRPS could be a consideration given the patient's complaint of neuropathy and the presence of significant pain and swelling in one extremity.

Each of these diagnoses should be considered in the context of the patient's overall clinical presentation, and further diagnostic testing or specialist consultation may be necessary to determine the underlying cause of the patient's symptoms.