Differential Diagnosis for Testicular Pain with Uncomplicated Right Epididymal Cyst on US

• Single Most Likely Diagnosis
  • Epididymitis: This is the most likely diagnosis given the presence of testicular pain and an epididymal cyst. The cyst itself may be asymptomatic, but inflammation of the epididymis (epididymitis) could cause pain.
• Other Likely Diagnoses
  • Spermatocele: Similar to an epididymal cyst but contains sperm, which could potentially cause discomfort or pain if it becomes large enough or if there's associated epididymal inflammation.
  • Testicular torsion (partial or intermittent): Although the ultrasound shows an uncomplicated epididymal cyst, intermittent testicular torsion could cause recurrent pain and might not always be evident on imaging.
  • Varicocele: Enlargement of the veins within the scrotum, which can cause a feeling of heaviness or pain, especially if the varicocele is large.
• Do Not Miss Diagnoses
  • Testicular cancer: Although less common, testicular cancer can present with pain and a mass. The presence of an epididymal cyst does not rule out testicular cancer, and any solid components within the testicle should be thoroughly evaluated.
  • Acute epididymitis due to sexually transmitted infection (STI) or other bacterial infection: Failing to diagnose and treat an STI or bacterial infection could lead to complications such as infertility or chronic pain.
  • Pyocele or abscess: An infected epididymal cyst could lead to significant morbidity if not properly treated.
• Rare Diagnoses
  • Adrenal rest tumors: Rare tumors that can occur in the testicles and may cause pain.
  • Polyarteritis nodosa (PAN): A systemic vasculitis that can affect the testicular arteries and cause pain.
  • Henoch-Schönlein purpura (HSP): A form of vasculitis that can rarely involve the testicles and cause pain.

Each of these diagnoses should be considered in the context of the patient's full clinical presentation, including history, physical examination, and laboratory findings, to ensure an accurate diagnosis and appropriate management.