What is the differential diagnosis for an uncircumcised 5-year-old male presenting with penile swelling?

Differential Diagnosis for Penile Swelling in an Uncircumcised 5-Year-Old Male

The most common causes of penile swelling in an uncircumcised 5-year-old boy are phimosis with balanitis, lichen sclerosus causing phimosis, paraphimosis, trauma-related edema, and cellulitis.

Immediate Life-Threatening Conditions to Rule Out First

Paraphimosis

• Paraphimosis is a urologic emergency requiring immediate manual reduction or surgical intervention to prevent vascular compromise and tissue necrosis 1
• Look for a retracted foreskin that cannot be returned to its normal position, creating a constricting band with distal penile swelling and pain 1
• The glans penis will be swollen, tender, and potentially dusky or cyanotic if vascular compromise is present 1

Fournier Gangrene (Rare but Critical)

• Presents with rapidly progressive penile and scrotal swelling, erythema, crepitus, systemic toxicity (fever, tachycardia), and severe pain 2
• Most patients have underlying conditions like diabetes, but 20% have no identifiable risk factors 2
• Requires immediate surgical debridement and broad-spectrum antibiotics including penicillin plus clindamycin 2

Common Non-Emergent Causes

Phimosis with Balanitis

• Phimosis (inability to retract foreskin) is the most common penile condition in uncircumcised boys at this age and frequently presents with swelling when complicated by infection 2
• Look for inability to retract the foreskin, erythema, purulent discharge, and localized swelling of the prepuce 2
• May present with dysuria, poor urinary stream, or ballooning of foreskin during urination 2

Lichen Sclerosus

• Lichen sclerosus affects the prepuce in boys and is a significant cause of pathologic phimosis, documented in 14-100% of boys undergoing circumcision for phimosis 2
• Presents with white, atrophic patches on the foreskin, meatal stenosis, decreased penile sensitivity, and soreness rather than itch 2
• Can lead to scarring, stenosis, and obstruction causing dysuria and poor urinary stream 2
• Biopsy is essential for definitive diagnosis showing hyperkeratosis, homogenized collagen, and lymphocytic infiltrate 2
• Perianal involvement is extremely rare in males 2

Traumatic Edema

• Penile friction edema can occur from trauma, masturbation, or the Koebner phenomenon (trauma-induced skin changes) 2, 3
• Presents as localized or diffuse penile swelling without signs of infection 3
• Diagnosis is by exclusion after ruling out infectious and obstructive causes 3
• Treatment involves observation and avoiding further trauma 3

Cellulitis

• Bacterial infection of penile shaft soft tissue, commonly occurring in uncircumcised boys 4
• Look for diffuse penile shaft swelling, erythema, warmth, tenderness, and possible purulent discharge 4
• Streptococcus species are common causative organisms 4
• Ultrasound shows increased echogenicity of soft tissue with markedly increased Doppler signal 4
• Requires broad-spectrum antibiotics 4

Strangulation Injury

• Self-inflicted or accidental placement of constricting objects (hair, thread, rubber bands) around penis or foreskin 5
• Presents with distal penile swelling, pain, and visible constricting object 5
• Requires immediate removal of constricting object and assessment for tissue viability 5

Less Common but Important Differentials

Insect Bite or Allergic Reaction

• Localized swelling with erythema, pruritus, and possible visible bite mark
• Usually self-limited with antihistamine treatment

Acute Idiopathic Scrotal Edema (Can Extend to Penis)

• Rare, self-limiting condition with marked swelling, usually painless or minimally painful 6, 7
• Diagnosis of exclusion after ruling out more serious causes 6

Diagnostic Approach Algorithm

Step 1: Assess for emergencies

• Check for paraphimosis (retracted, constricted foreskin with distal swelling) → immediate manual reduction 1
• Evaluate for signs of necrotizing infection (crepitus, systemic toxicity, rapid progression) → immediate surgical consultation 2
• Look for constricting foreign body → immediate removal 5

Step 2: Obtain focused history

• Duration and progression of swelling (sudden vs. gradual)
• Associated symptoms: pain, dysuria, discharge, fever, urinary stream changes 2
• Recent trauma, sexual activity (inappropriate for age 5, but consider abuse), or self-manipulation 2, 3
• Previous episodes or chronic foreskin problems 2

Step 3: Physical examination

• Assess ability to retract foreskin (do NOT force retraction if resistance) 2
• Examine for white patches, scarring, or atrophic changes suggesting lichen sclerosus 2
• Check for erythema, warmth, tenderness, discharge indicating infection 4
• Palpate for crepitus or fluctuance 2
• Examine urethral meatus for blood or stenosis 2

Step 4: Diagnostic testing when indicated

• Ultrasound with Doppler if cellulitis suspected to confirm diagnosis and assess extent 4
• Urinalysis and culture if urinary symptoms present 2
• Wound culture if purulent discharge present 4
• Biopsy if lichen sclerosus suspected to confirm diagnosis and rule out malignancy (extremely rare in children but documented) 2

Critical Pitfalls to Avoid

• Never forcibly retract a phimotic foreskin, as this can cause paraphimosis or traumatic injury 2
• Do not dismiss white patches on the foreskin as simple inflammation; lichen sclerosus requires specific diagnosis and treatment 2
• Do not delay evaluation of rapidly progressive swelling with systemic symptoms, as Fournier gangrene has high mortality without prompt surgical intervention 2
• Consider non-accidental trauma if history is inconsistent with physical findings, especially with associated infections or unusual injury patterns 2
• Penile problems are 2.9-fold more common in circumcised boys compared to uncircumcised boys, but when uncircumcised boys present with problems, phimosis and balanitis are the leading causes 8