A 16-year-old girl presents with a sudden onset of painful ulcers on her vulva. She denies any recent sexual activity, systemic symptoms, or history of similar episodes. Examination reveals multiple large, deep, necrotic ulcers with irregular borders on the labia minora and majora. No other mucosal surfaces are involved and she does not have any skin lesions in any other areas. She recently recovered from an illness where she had cervical lymphadenopathy and felt fatigued. Routine laboratory testing, including sexually transmitted infection (STI) screening, is negative. What is the most likely diagnosis?

A. Herpes simplex virus infection

B. Behçet’s disease

C. Hidradenitis suppurativa

D. Lipschütz ulcers

E. Syphilitic chancres

Rationale:

Genital ulcerations can be caused by a variety of etiologies including herpetic infections, bacterial infections, autoimmune conditions, vulvovaginal lichen planus, and immunobullous diseases. The age of the patient, negative STI testing, and associated lymphadenopathy (from presumed EBV) should help guide the reader to the correct answer choice. 

Correct Answer: D. Lipschütz ulcers

Lipschütz ulcers are acute, painful, genital ulcers that occur in adolescent girls and young women. Lesions are confined to the vulva, without involvement of other mucosal sites, distinguishing them from conditions like Behçet’s disease. They are often associated with viral infections, particularly EBV. The history of fatigue and lymphadenopathy alluded to a recent EBV infection.  

Incorrect answer choices: 

A. Herpes simplex virus (HSV) typically causes grouped vesicles or shallow ulcers on an erythematous base and can be confirmed with PCR testing. 

B. Behçet’s disease can present with recurrent genital ulcers but is often associated with oral ulcers, uveitis, and systemic vasculitis. The absence of these findings makes this diagnosis less likely. 

C. Although hidradenitis suppurativa (HS) can present with ulcers as a primary finding and the patient is of an appropriate age for disease onset, one would expect to see other typical HS lesions such as abscesses, nodules, tunnels, or comedones and involvement of the thighs, groin, buttocks, inframammary region, or axilla. 

E. Syphilitic chancres are painless, with an indurated border, caused by Treponema pallidum and positive serologic tests (RPR, FTA-ABS) should help confirm this diagnosis. The painful and necrotic nature of the ulcers described in the vignette is not consistent with syphilis, and STI testing was negative.

Additional reading at Barnhill's Dermatopathology Chapter 38: Disorders of the Genital Mucosa and Fitzpatrick's Dermatology Chapter 163: Exanthematous Viral Diseases