Diagnosis: Lichen sclerosus
Based on the history and clinical findings, including the classic figure-8 pattern, we diagnosed childhood lichen sclerosus (LS) in this patient. LS is a chronic inflammatory skin disorder that primarily affects the genital mucosa. The disorder can present at any age, but is most common among postmenopausal women, with a prevalence estimated to be as high as one in 30.1-3 A second incidence peak is observed in prepubescent girls, with a prevalence of one in 900.3,4 LS is less common in men and boys, with a female-to-male ratio that can reach 10:1.5 The classic symptoms of LS are pruritus and pain, which may be intermittent or persistent.
In girls, initial manifestations may be constipation, dysuria, or even behavioral symptoms such as night fears, which can occur because children are less active at night and become more aware of urinary discomfort.1,2,6 Typical signs of LS are thin atrophic plaques that spare the vagina and cervix. The plaques can be ivory-white, erythematous, or violaceous. Some patients have perianal lesions as well, and can display the pathognomonic figure-8 pattern of porcelain plaques around the vulva and anus.5
With more advanced disease, erosions, lichenification, and even distortion of vulvar architecture may occur.2,4,7 In severe cases, labia resorption and clitoral phimosis may develop.5 Complications include secondary infection, dyspareunia, and psychosexual distress. The most worrisome sequela of LS is squamous cell carcinoma of the vulva (SCCV), which occurs in 5% of female patients with LS.4
In men and boys, LS typically involves the foreskin and the glans, while sparing the perianal region.5 Scarring of the foreskin can lead to phimosis, and patients may complain of painful erections and difficulty urinating. LS can also occur away from the genitalia in both males and females.
Autoimmune mechanisms, genetics, and hormones play a role
The exact pathogenesis of LS remains unknown, but multiple factors are likely at work.
Autoimmune mechanisms. Up to 60% of women with LS have an autoimmune disorder, which is most commonly vitiligo, alopecia areata, or thyroid disease.5 In addition, 67% of patients have autoantibodies against extracellular matrix protein 1, and 30% have them against bullous pemphigoid antigen 180.1,8
Genetics. LS is associated with certain human leukocyte antigen class II haplotypes (especially DQ7) and with polymorphisms at the interleukin-1 receptor antagonist gene locus.5,6,9
Hormones. The clear peaks of incidence during times of low estrogen, and a higher incidence in patients with Turner syndrome or kidney disease, suggest that low estrogen may play a role in the development of LS, as well.1,5,6
While it is generally accepted that trauma may trigger LS via the Koebner phenomenon (the appearance of lesions at the site of injury), there is debate as to whether microbes—especially Borrelia burgdorferi and human papillomavirus (HPV)—might play a role.1,5
Diagnosis is often delayed, misdiagnosis is common
The average delay from symptom onset to diagnosis of LS is 1.3 years, and up to 84% of childhood LS is misdiagnosed before referral.2,9 The differential diagnosis includes:
Sexual abuse. In prepubertal girls presenting with genital redness, the can’t-miss diagnosis is sexual abuse, which occurs in more than 25% of children in the United States.10 Initial manifestations may be regression in developmental milestones, such as new-onset bedwetting, or behavioral changes such as social withdrawal or declining academic performance.11
However, physicians must be conscientious about ruling out medical etiologies before prematurely diagnosing abuse. Fourteen percent of girls with LS are incorrectly diagnosed as having been sexually abused.2 A clinical pearl is that while LS may resemble abuse on exam, it rarely affects the hymenal structure.12 It is also important to keep in mind that the 2 entities are not incompatible, as sexual abuse leading to LS via Koebnerization is a well-described phenomenon.12
Lichen planus. LP, which is also an immune-mediated inflammatory disorder affecting the vulva, classically presents with the 6 Ps: pruritic, polygonal, planar, purple papules and plaques.4 LP is distinguished from LS by being rare in childhood, having a predilection for the flexor wrists, and involving the oral and vaginal mucosa.4
Lichen simplex chronicus (LSC) is a chronic, circumscribed, pruritic, eczematous condition that becomes lichenified with thickened skin secondary to repeated scratching.13 Children with atopic dermatitis can develop LSC, but other children can also develop the scratch-itch cycle that results in the thickened plaques of LSC. Like LS, LSC can occur in areas other than the genitalia, including the neck and feet.14
Allergic contact dermatitis can occur in the genital area from diaper creams, soaps, and perfumes. Irritant contact dermatitis can occur from exposure to diarrhea, bedwetting, and other irritants. Contact dermatitis is less likely to have the classic figure-8 pattern seen in LS.
Psoriasis in the genital area can be confused with LS. However, psoriasis favors the groin creases in what is called inverse psoriasis. In addition, psoriasis tends to involve multiple areas, including the extensor surfaces of the elbows and knees, the nails, and the scalp.
Vitiligo can present on the genitals as circumscribed hypopigmented and depigmented patches that are flat. Vitiligo is asymptomatic, and the only pathology is the change in skin color. With LS, there is lichenification, atrophy, and sclerosis.4 Vitiligo often occurs with bilateral symmetric involvement in areas of trauma including the face, neck, scalp, elbows, wrists, hands, knees, ankles, and feet.