Differential Diagnosis for a 67-year-old Male with Diabetes and a Knot in a Vein on the Side of His Penis

• Single most likely diagnosis:
  • Varicocele: This condition is characterized by an enlargement of the veins within the scrotum, similar to varicose veins. Given the description of a "knot in a vein" and the location, a varicocele is a plausible diagnosis, especially considering the patient's age and the fact that varicoceles can be more common or become more noticeable with advancing age.
• Other Likely diagnoses:
  • Thrombophlebitis: This refers to a blood clot that causes inflammation in a vein, which could present as a painful knot or swelling. Diabetes increases the risk of thrombophlebitis due to its effects on blood vessels and clotting.
  • Spermatic cord cyst or hydrocele: While these conditions primarily involve the scrotum, a cyst or fluid accumulation could potentially feel like a "knot" and might be noticeable on the side of the penis if large enough.
• Do Not Miss diagnoses:
  • Testicular cancer: Although less likely, testicular cancer can present with a painless lump or swelling. Given the potential severity of this diagnosis, it's crucial not to miss it, even if the presentation is atypical.
  • Penile or scrotal cellulitis/abscess: Infections in this area can cause swelling, redness, and pain, which might be perceived as a "knot." Diabetes increases the risk of infections, making this a critical consideration.
• Rare diagnoses:
  • Penile venous thrombosis: A blood clot in the veins of the penis, which could present with pain and swelling.
  • Lymphoma or other malignancies: Rarely, lymphomas or other cancers can present with masses or swellings in the genital area, including the penis and scrotum.