What are the likely causes and first-line management for a 17-year-old female with acute unilateral labial minora swelling and irritation, no sexual activity, and no palpable mass, abscess, or cyst?

Acute Unilateral Labial Minora Swelling in a Non-Sexually Active Adolescent

In a 17-year-old with acute unilateral labial minora swelling without a palpable mass, the most likely causes are contact dermatitis/irritant vulvovaginitis, early Bartholin or Skene gland infection, or early lichen sclerosus, and initial management should include conservative measures with topical hydrocortisone for irritation while maintaining high suspicion for infectious causes that may require antibiotic therapy. 1, 2

Most Likely Differential Diagnoses

Non-Specific Vulvovaginitis (Most Common)

• Non-specific vulvovaginitis is the most common cause of vulvar symptoms in adolescents, presenting with irritation, swelling, and discomfort without identifiable infection 3
• Look specifically for: recent use of new soaps, detergents, tight clothing, shaving/hair removal practices, or poor hygiene habits 1
• The acute onset (1 day) and absence of palpable mass makes simple irritant contact dermatitis highly likely 3

Early Bartholin or Skene Gland Infection

• Bartholin gland infections present with swelling, erythema, and tenderness extending into the entire labia minora, even before a discrete abscess forms 1
• The Bartholin glands are located at the 4 and 8 o'clock positions in the posterior vestibule 1
• Although any vaginal organism can infect these glands, STI pathogens including gonorrhea and chlamydia are common culprits 1, 2
• Despite no sexual activity history, STI testing should still be considered given the anatomic location and presentation 2

Early Lichen Sclerosus

• Lichen sclerosus has a bimodal presentation with one peak in prepubertal/adolescent girls 1, 2, 4
• Early presentation may show only swelling and irritation before classic porcelain-white plaques develop 1, 4
• Areas of ecchymosis often accompany the lesions and should not be mistaken for trauma 1, 4
• The main symptom is itch, but pain occurs with erosions or fissures 1, 4

First-Line Management Algorithm

Immediate Conservative Management

• For external genital itching and irritation in adolescents, apply hydrocortisone topical cream to affected area not more than 3 to 4 times daily 5
• Instruct on proper hygiene: gentle cleansing with mild soap and warm water, thorough rinsing, and gentle drying by patting 5
• Avoid potential irritants: discontinue new soaps, detergents, fabric softeners, tight clothing, and shaving 1

When to Escalate to Antibiotic Therapy

• If there is any suggestion of Bartholin or Skene gland involvement (tenderness at 4 or 8 o'clock positions, erythema extending into labia), treat empirically with Ceftriaxone 250 mg IM single dose PLUS Doxycycline 100 mg orally twice daily for 10 days 2
• Alternative regimen: Ofloxacin 300 mg orally twice daily for 10 days for enteric organisms or antibiotic allergies 2

Diagnostic Testing to Obtain

• STI testing with gonorrhea and chlamydia nucleic acid amplification tests should be performed, particularly if Bartholin or Skene gland involvement is suspected 2
• Consider viral culture for HSV if any ulcerations develop 2
• If symptoms persist beyond 1-2 weeks despite conservative management, biopsy is necessary to confirm lichen sclerosus and rule out squamous cell carcinoma 2

Critical Follow-Up Parameters

48-72 Hour Reassessment

• Patient should be reassessed within 48-72 hours to evaluate response to initial management 1
• Look for: progression of swelling, development of fluctuance suggesting abscess formation, appearance of white plaques, or ulcerations 1, 2

Red Flags Requiring Urgent Escalation

• Development of fever, systemic symptoms, or inability to void 1
• Rapid progression of swelling or development of palpable mass 1
• Appearance of porcelain-white plaques with ecchymosis (suggests lichen sclerosus requiring dermatology referral) 1, 4
• Persistent symptoms beyond 1-2 weeks despite appropriate conservative management 2

Common Pitfalls to Avoid

• Do not dismiss the possibility of STI-related Bartholin gland infection solely based on reported sexual inactivity history, as adolescent sexual history may be incomplete 1, 2
• Do not overlook lichen sclerosus in adolescents, as it has a bimodal distribution with significant prepubertal/adolescent presentation 1, 2, 4
• Never assume ecchymosis in adolescent girls definitively indicates trauma without considering lichen sclerosus 1, 2
• Do not initiate prolonged empiric antibiotic therapy without establishing infectious etiology, as most cases are non-specific irritant vulvovaginitis 3
• Recognize that lichen sclerosus requires lifelong surveillance for malignant transformation (3.5-5% risk), not just symptomatic treatment 2, 4