Differential Diagnosis for Sudden Pain and Nodule on Testicle in a 15-Year-Old Male

Single Most Likely Diagnosis

• Epididymitis: This is an inflammation of the epididymis, a tube at the back of the testicle that stores and carries sperm. It's a common cause of testicular pain and swelling, especially in adolescent males. The sudden onset of pain and the presence of a nodule could be indicative of epididymitis, which is often caused by bacterial infection.

Other Likely Diagnoses

• Testicular Torsion: Although less common, testicular torsion is a significant consideration due to its emergency nature. It occurs when the spermatic cord becomes twisted, cutting off the blood supply to the testicle. While it typically presents with severe pain and swelling, a nodule might not be the primary finding, but it cannot be ruled out without further evaluation.
• Varicocele: This condition involves an enlargement of the veins within the scrotum, similar to varicose veins. It can cause a palpable nodule or "bag of worms" feeling and may be associated with discomfort or pain, especially after prolonged standing.

Do Not Miss Diagnoses

• Testicular Cancer: Although rare in adolescents, testicular cancer can present as a painless testicular mass. However, given the acute presentation with pain, it's less likely but must be considered to avoid missing a potentially life-threatening condition.
• Appendix Testis Torsion (Hydatid of Morgagni): This is a small, vestigial appendage attached to the testis that can twist and cause severe pain, mimicking testicular torsion. It's a rare condition but important to recognize due to its need for prompt surgical intervention.

Rare Diagnoses

• Spermatocele: A spermatocele is a cystic structure that arises from the head of the epididymis and contains sperm. It's usually painless but could potentially cause discomfort if large enough or if it becomes inflamed.
• Cyst of the Epididymis: Similar to a spermatocele, a cyst of the epididymis is a rare condition that could present as a nodule but is typically asymptomatic unless it becomes large or infected.
• Henoch-Schönlein Purpura (HSP): This is a form of vasculitis that can affect various parts of the body, including the testicles, leading to pain and swelling. It's more commonly associated with skin, joint, and gastrointestinal symptoms but can have testicular involvement.