Differential Diagnosis for Itching in Groin and Around Head After Starting Testosterone

• Single Most Likely Diagnosis
  • Acne or folliculitis: Testosterone can increase sebum production, leading to acne or folliculitis, which can cause itching in the groin and around the head.
• Other Likely Diagnoses
  • Allergic contact dermatitis: The patient may be allergic to the testosterone formulation or other ingredients in the product, causing an allergic reaction and itching.
  • Seborrheic dermatitis: Testosterone can exacerbate seborrheic dermatitis, a common skin condition that causes itching and flaking, particularly on the scalp.
  • Tinea cruris (jock itch): The warm, moist environment of the groin can lead to fungal infections like tinea cruris, which can cause itching and be exacerbated by testosterone use.
• Do Not Miss Diagnoses
  • Testosterone-induced polycythemia: Although not directly related to itching, testosterone can increase red blood cell count, leading to polycythemia, which can be life-threatening if left untreated.
  • Liver dysfunction: Testosterone can affect liver function, and itching can be a symptom of liver disease; it is essential to monitor liver function tests in patients taking testosterone.
• Rare Diagnoses
  • Porphyria cutanea tarda: A rare genetic disorder that can cause itching, blisters, and skin fragility, which may be exacerbated by testosterone use.
  • Erythromelalgia: A rare condition characterized by burning pain, itching, and redness, typically in the hands and feet, but can also occur in the groin and head.