Differential Diagnosis for Sedimentation Rate-Westergren 18 in a Patient with Negative STI and Penile Irritation

• Single Most Likely Diagnosis
  • Reactive Arthritis (Reiter's Syndrome): This condition is characterized by a combination of arthritis, urethritis, and conjunctivitis, often following a bacterial infection. The negative STI test does not rule out a recent infection that has been cleared, and the elevated sedimentation rate suggests an inflammatory process. Penile irritation could be related to urethritis, a component of reactive arthritis.
• Other Likely Diagnoses
  • Psoriasis: Psoriasis can cause penile irritation and has a systemic inflammatory component that could elevate the sedimentation rate. The absence of a clear psoriatic rash does not rule out this diagnosis, as psoriasis can have varied presentations.
  • Lichen Sclerosus: This is a skin condition that can cause penile irritation and has been associated with an increased risk of autoimmune diseases, which could explain the elevated sedimentation rate.
  • Balanitis: Inflammation of the glans penis, which could be due to various causes including infections (despite a negative STI test, other pathogens could be involved) or irritants. The inflammation could contribute to an elevated sedimentation rate.
• Do Not Miss Diagnoses
  • Systemic Lupus Erythematosus (SLE): Although less common, SLE is a critical diagnosis not to miss due to its potential for severe systemic complications. It can cause a wide range of symptoms, including skin rashes and arthritis, and is associated with elevated inflammatory markers like the sedimentation rate.
  • Cancer (e.g., Penile Cancer): While rare, penile cancer can cause irritation and could potentially lead to systemic inflammation, reflected by an elevated sedimentation rate. Early detection is crucial for treatment outcomes.
• Rare Diagnoses
  • Behçet's Disease: A form of vasculitis that can cause a wide range of symptoms, including genital ulcers and skin lesions, which might be mistaken for penile irritation. It is associated with systemic inflammation.
  • Sarcoidosis: A condition characterized by the growth of granulomas in various parts of the body, which can lead to inflammation and elevated sedimentation rates. It can cause skin lesions and, less commonly, genital involvement.