Differential Diagnosis for Painful Nodule on Left Testis

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 often caused by a bacterial infection and can present with sudden onset of pain and swelling, which may include a palpable nodule. The pain can be severe and is usually accompanied by other symptoms like redness, warmth, and swelling of the scrotum.

Other Likely Diagnoses

• Testicular Torsion: Although more commonly associated with severe, sudden pain rather than a nodule, testicular torsion can sometimes present with a palpable abnormality due to the twisting of the spermatic cord. It's a medical emergency that requires immediate attention.
• Orchitis: Inflammation of one or both testicles, usually caused by bacterial or viral infections. It can present with pain, swelling, and possibly a nodule if there's an associated abscess or significant inflammation.
• Spermatocele or Epididymal Cyst: These are benign cysts that can form on the epididymis and may cause a palpable nodule. While they are typically painless, inflammation or rupture can cause sudden pain.

Do Not Miss Diagnoses

• Testicular Cancer: Although less common, testicular cancer can present as a painless testicular mass. However, some types can cause pain, especially if there's bleeding or rapid growth. Given the potential for serious outcomes if missed, it's crucial to consider this diagnosis.
• Appendix Testis Torsion (Hydatid of Morgagni): A small appendage at the top of the testis can twist, causing severe pain and potentially a palpable nodule. It's less common than testicular torsion but requires prompt treatment.

Rare Diagnoses

• Henoch-Schönlein Purpura (HSP): A form of vasculitis that can affect various parts of the body, including the testicles, leading to pain and swelling. It's more common in children but can occur in adults.
• Malignant Tumors of the Epididymis: Rare tumors that can cause a painful nodule due to rapid growth or invasion into surrounding structures.
• Granulomatous Orchitis: A rare inflammatory condition that can mimic testicular cancer or other conditions, causing pain and a palpable mass. It's often associated with systemic diseases like sarcoidosis.