Differential Diagnosis for a Pimple on the Penis
- Single most likely diagnosis
- Folliculitis: This is an inflammation of the hair follicles, which can occur anywhere on the body, including the genital area. It's often caused by bacterial or fungal infections and can present as a pimple-like lesion.
- Other Likely diagnoses
- Ingrown hair (Pseudofolliculitis): This condition occurs when hair curls back into the skin, causing inflammation and potentially leading to a pimple-like appearance.
- Genital herpes: Although it typically presents with multiple vesicles, a single lesion can occur, especially in the initial stages.
- Syphilis (primary stage): The primary stage of syphilis can manifest as a single, painless chancre, which might resemble a pimple.
- Molluscum contagiosum: A viral infection that causes small, pearly, or flesh-colored bumps.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Genital warts (caused by HPV): While often multiple, a single wart can occur and is important to diagnose due to its association with cervical and other cancers.
- Squamous cell carcinoma or other skin cancers: Although rare, any new or changing skin lesion in the genital area should be evaluated for the possibility of skin cancer.
- Rare diagnoses
- Hidradenitis suppurativa: A chronic skin condition that can cause painful, inflamed bumps in the groin and genital area, though it's less common for it to present as a single "pimple."
- Keratoacanthoma: A rare, low-grade malignancy that can resemble a large pimple but is typically found on sun-exposed areas, making it less likely in the genital area.
- Erythema nodosum: An inflammatory condition that can cause red, painful nodules, typically on the legs, but can occasionally occur in the genital area.