Differential Diagnosis for 44 YOM with Cerebral Palsy and Lower Left Ankle/Shin Swelling

• Single Most Likely Diagnosis
  • Cellulitis: Given the patient's presentation of a red, swollen lower left ankle/shin without any visible abrasion or cut, and elevated CRP, cellulitis is a strong consideration. The absence of fever and a normal WBC count does not rule out cellulitis, as these findings can be variable.
• Other Likely Diagnoses
  • Deep Vein Thrombosis (DVT): Although the D-dimer is negative, which lowers the likelihood, it's not entirely ruled out, especially in a patient with potential decreased mobility due to cerebral palsy. However, the clinical presentation and negative D-dimer make it less likely.
  • Soft Tissue Injury: Given the patient's cerebral palsy, there could be an increased risk of falls or injuries that might not be immediately apparent or reported, leading to soft tissue swelling.
• Do Not Miss Diagnoses
  • Osteomyelitis: Although less common, osteomyelitis could present with swelling and elevated CRP without an obvious source of infection. It's crucial to consider, especially in patients with potential compromised mobility or sensory perception.
  • Septic Arthritis: This is another critical diagnosis to consider, especially if the patient has a prosthetic joint or has had previous joint issues. The absence of fever does not rule out septic arthritis.
• Rare Diagnoses
  • Erythema Nodosum: This condition could present with swollen, red areas, typically on the shins. It's often associated with an underlying condition or infection and could be considered if other diagnoses are ruled out.
  • Vasculitis: Various forms of vasculitis could present with skin manifestations, including swelling and redness. This would be a diagnosis of exclusion, requiring further investigation if suspected.