Differential Diagnosis

The patient's presentation of small papules along the balanopreputial sulcus, resembling pearly penile papules, but with a history of a reddish lesion and intermittent itching, suggests several possible diagnoses. The following categories outline the differential diagnoses:

• Single Most Likely Diagnosis
  • Pearly Penile Papules (PPP): This condition is characterized by small, dome-shaped papules on the corona or sulcus of the penis. The patient's description of the lesions and their location is consistent with PPP. The fact that similar papules have appeared on the other side and the presence of intermittent itching, particularly on the side with more papules, supports this diagnosis.
• Other Likely Diagnoses
  • Eczema/Dermatitis: The history of wearing the same underwear for 3 consecutive days could have led to irritation, and the subsequent treatment with steroids and antibiotics might have masked the symptoms temporarily. The incomplete epithelial regeneration and intermittent itching could be indicative of an underlying eczematous process.
  • Folliculitis: Given the patient's history of antibiotic treatment and the appearance of new papules, folliculitis (inflammation of the hair follicles) is a possible diagnosis, especially if the patient has curly or coarse hair in the genital area that could lead to follicular occlusion.
  • Contact Dermatitis: Allergic or irritant contact dermatitis could explain the initial lesion and the subsequent development of papules, especially if the patient has been exposed to new soaps, detergents, or other products that come into contact with the genital area.
• Do Not Miss Diagnoses
  • Squamous Cell Carcinoma (SCC) or Other Malignancies: Although less likely given the patient's age and the appearance of the lesions, any non-healing lesion, especially one that has not resolved after 8 months, warrants consideration of malignancy. Biopsy would be essential to rule out SCC or other cancers.
  • Sexually Transmitted Infections (STIs): Conditions like secondary syphilis can present with papular lesions. Given the location and description, it's crucial to consider STIs, even if the patient reports no other symptoms or risk factors.
• Rare Diagnoses
  • Lichen Nitidus: A rare condition characterized by tiny, shiny, flat-topped papules that can appear on the penis. It might be considered if the lesions are extremely small and flat.
  • Lichen Planus: An inflammatory condition that can affect the skin and mucous membranes, sometimes presenting with papular lesions. It's less common in the genital area but could be a consideration if other diagnoses are ruled out.

Further Evaluation and Management

• Detailed History and Physical Examination: Including questions about sexual history, use of new products, and any changes in hygiene practices.
• Biopsy: For the non-healing lesion to rule out malignancy.
• Dermatological Examination: To closely examine the papules and assess for any other skin changes.
• STI Screening: To rule out sexually transmitted infections.
• Patch Testing: If contact dermatitis is suspected, to identify specific allergens.
• Treatment Trials: Based on the most likely diagnoses, such as topical steroids for eczema or specific treatments for folliculitis.

Given the complexity and the need for a definitive diagnosis, referral to a dermatologist or a urologist with experience in genital dermatology would be appropriate for further evaluation and management.