In a 2-year-old boy with a small, painless, mobile, cystic lesion on the penis without phimosis, fever, or dysuria, what are the differential diagnoses and recommended management?

Small Cystic Penile Swelling in a 2-Year-Old Child

The most likely diagnosis is a smegma pearl or epidermoid inclusion cyst, both benign conditions that typically resolve spontaneously or can be managed with simple surgical excision if symptomatic. 1, 2

Differential Diagnoses

Most Likely: Smegma Pearl

• Smegma pearls are normal collections of desquamated epithelial cells, fat, and protein that appear as yellowish, mobile, non-tender subcutaneous nodules on the penile shaft 1
• These occur commonly in uncircumcised young boys as part of the natural separation process of fused foreskin from glans epithelium 1
• Key distinguishing features: no covering sac, yellowish color, completely benign, and spontaneously resolve over time 1
• No treatment is required beyond parental reassurance and monitoring for spontaneous resolution 1

Epidermoid/Epidermal Inclusion Cyst

• Present as well-circumscribed, firm, mobile, non-tender subcutaneous masses that can occur anywhere on the penis 2, 3
• These are benign, keratin-filled lesions lined with stratified squamous epithelium 2
• Can develop as a late complication of circumcision (though your patient has no phimosis, suggesting intact foreskin) 3
• Surgical excision with adequate margins is curative when symptomatic, with minimal recurrence risk 2

Dermoid Cyst

• Congenital subcutaneous swellings originating from sequestration of embryonic epithelium, presenting as well-circumscribed, firm, non-tender masses 4
• Composed of sebaceous fluid, keratin, cholesterol crystals, calcium, hair follicles, sweat glands, and sebaceous glands 4
• Extremely rare on the prepuce but should be considered in the differential 4
• Surgical excision is the definitive treatment 4

Steatocystoma Simplex

• Uncommon skin lesion that can rarely occur on penile foreskin 5
• Presents as mobile, compressible, non-tender subcutaneous mass 5
• Diagnosis confirmed by histopathology after excision 5

Less Likely Given Clinical Presentation

• Lichen sclerosus typically causes phimosis in pediatric males and would not present as an isolated cystic swelling 6
• Testicular/scrotal pathology is excluded by the penile location 6, 7

Recommended Management Approach

Initial Assessment

• Document exact location, size, mobility, consistency, and relationship to surrounding structures (submucosa, shaft skin, foreskin) 6
• Assess for any signs of infection, inflammation, or secondary changes 4
• Examine for multiple lesions elsewhere on the body to distinguish between simplex and multiplex variants 5

Conservative Management (First-Line for Smegma Pearl)

• Provide parental reassurance that smegma pearls are benign and resolve spontaneously 1
• Monitor for resolution over several months 1
• Educate parents about normal penile development and foreskin separation 1

When to Consider Surgical Intervention

• Persistent lesions beyond 6-12 months of observation 2
• Symptomatic lesions causing discomfort, pruritus, or functional impairment 2, 5
• Parental anxiety despite reassurance 1
• Diagnostic uncertainty requiring histopathological confirmation 4, 2

Surgical Approach When Indicated

• Simple excision under local or general anesthesia (age-dependent) 4, 2
• Ensure adequate margins to prevent recurrence 2
• Submit all excised tissue for histopathological examination to confirm diagnosis 4, 2, 5
• Same-day discharge is typical for uncomplicated cases 5

Critical Clinical Pitfalls to Avoid

• Do not perform unnecessary investigations or specialist referrals for typical smegma pearls - this leads to increased parental anxiety and healthcare costs 1
• Never assume malignancy without histopathological confirmation - all these cystic lesions are benign 4, 2
• Do not confuse smegma pearls (no epithelial covering) with smegma cysts (well-formed epithelial wall) or smegmoliths (calcified, stone-like) 1
• Avoid aggressive intervention for asymptomatic lesions in young children - observation is appropriate first-line management 1

Referral Considerations

Pediatric urology or pediatric surgery consultation is appropriate if: 6

• Diagnostic uncertainty persists after initial evaluation
• Surgical excision is planned
• The lesion demonstrates concerning features (rapid growth, fixation to deeper structures, signs of malignancy)
• Multiple or recurrent lesions develop