Differential Diagnosis for Male Patient with Small Non-Painful Bumps on Penis

Single Most Likely Diagnosis

• Pearly Penile Papules (PPP): These are small, non-painful bumps that appear on the penis, often in a ring-like fashion around the corona. They are benign, common, and not associated with any sexually transmitted infection, which aligns with the negative testing and herpes swab results.

Other Likely Diagnoses

• Fordyce Spots: These are small, yellowish or white bumps on the penis (or other parts of the genitals) that are caused by the visibility of sebaceous glands. They are harmless and not contagious.
• Seborrheic Keratoses: While more common in older adults, these benign growths can appear anywhere on the body, including the genitals, and might be mistaken for other conditions.
• Angiokeratomas: These are small, dark lesions that can appear on the penis and are usually benign. They are caused by a dilation of blood vessels.

Do Not Miss Diagnoses

• Squamous Cell Carcinoma or Other Genital Cancers: Although rare, any new or changing lesions on the genitals should prompt consideration of cancer. Early detection is crucial for effective treatment.
• Syphilis: Despite the negative herpes swab, syphilis can cause a variety of skin lesions, including painless bumps or sores. It's essential to test for syphilis and other sexually transmitted infections (STIs) even if initial tests are negative, as some tests may not detect the infection early in its course.

Rare Diagnoses

• Lichen Nitidus: A rare skin condition characterized by tiny, shiny, flat-topped bumps that can appear on the genitals among other areas. It's usually harmless and resolves on its own.
• Molluscum Contagiosum: A viral infection that causes small, pearly, or flesh-colored bumps. It's contagious and can be spread by skin-to-skin contact or through contaminated objects.

Each of these diagnoses should be considered in the context of the patient's full medical history, physical examination, and laboratory results. Further testing or referral to a specialist may be necessary to confirm the diagnosis and initiate appropriate treatment.