Differential Diagnosis for Lateral Compartment of Leg Pain with Fever

• Single most likely diagnosis
  • Cellulitis or soft tissue infection: This is a common cause of leg pain and fever, especially if there is a history of trauma or skin breakage in the affected area. The lateral compartment of the leg is susceptible to such infections due to its anatomical location and potential for minor injuries.
• Other Likely diagnoses
  • Deep vein thrombosis (DVT): Although DVT typically presents with swelling, warmth, and discoloration of the affected limb, pain in the lateral compartment could be a symptom, especially if the thrombosis affects veins in that area. Fever might accompany DVT in some cases, particularly if there's an associated infection.
  • Peroneal tendonitis: Inflammation of the peroneal tendons, which run along the lateral aspect of the leg, can cause pain in this compartment. While fever is not a typical symptom, it could be present if the tendonitis is caused by an infectious process.
  • Compartment syndrome: This condition, characterized by increased pressure within a muscle compartment, can cause severe pain, especially with exertion. Fever might be present due to associated tissue injury or infection.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
  • Necrotizing fasciitis: A severe infection of the fascia, which can rapidly progress and is life-threatening. Early signs might include severe pain out of proportion to the physical findings, and fever. It's crucial to consider this diagnosis, even if it seems unlikely, due to its high mortality rate if not promptly treated.
  • Osteomyelitis: An infection of the bone, which can cause pain, fever, and other systemic symptoms. While less common, it's a critical diagnosis not to miss, especially in patients with a history of trauma, recent surgery, or those with compromised immune systems.
• Rare diagnoses
  • Eosinophilic fasciitis: A rare condition characterized by inflammation of the fascia, which can cause pain, swelling, and skin thickening. Fever might be present, and while it's not typically considered in the initial differential, it should be kept in mind for cases that do not respond to standard treatments.
  • Sarcoidosis: A systemic disease that can affect various parts of the body, including the muscles and bones, leading to pain and fever. Involvement of the lateral compartment of the leg would be unusual but could be considered in patients with known sarcoidosis or those with unexplained systemic symptoms.