ANSWER
Admittedly, this is a bit of a trick question—but with a good teaching point to make. A course of oral fluconazole (choice “a”) is futile, since there’s no reason to think this problem is yeast-driven and since the patient has already demonstrated a lack of response to topical imidazoles.
Punch biopsy (choice “b”) would be a good choice, but not in this area, where it could quickly become a bigger problem than the one the patient presented with. Sutures would not likely hold the biopsy wound together, and resultant infection is all too likely.
A KOH test to detect fungal or yeast elements (choice “c”) is unlikely to shed any light on the problem, given the lack of response to antifungal creams. Finally, there’s no reason to suspect a bacterial origin, so oral antibiotics such as cephalexin (choice “d”) would be useless (and had already been tried unsuccessfully).
The correct answer is none of the above (choice “e”).
DISCUSSION
This case illustrates why dermatology seems so maddeningly difficult to the uninitiated. Any experienced derm provider would know the correct diagnosis, lichen sclerosus et atrophicus (LS&A), because it presents in such a distinctive way (in limited locations, predominantly in women) and because the differential is so limited. But if you’ve never heard of LS&A, you’re unlikely to diagnose it, let alone know how to treat it.
LS&A is an inflammatory condition of unknown origin that affects the upper epidermis. It can present in extragenital locations (particularly shoulders and legs) but is far more common in genital areas. As exhibited in this case, it presents with well-defined pigment loss, which is especially easy to see in patients with darker skin.
Although more commonly seen in women, LS&A can occur in men, usually manifesting on the penile glans and distal foreskin of uncircumcised patients. The dry atrophic changes seen on the glans can lead to stenosis of the urethral meatus and, proximally, to adhesions (phimosis) of the foreskin. (This condition was termed balanitis xerotica obliterans [BXO] long before its pathologic process was determined to be identical to LS&A’s. Tissue specimens obtained during circumcisions performed for chronic phimosis often yield evidence of BXO.)
In women, untreated chronic LS&A can lead to sclerotic changes in and around the urethra and labia minora and can cause introital stenosis. This case is a bit atypical; LS&A more often manifests in perivaginal and perirectal areas, where the intense hypopigmentation produces a classic “figure eight” appearance.
The differential includes lichen simplex chronicus, psoriasis, lichen planus, contact/irritant dermatitis, and seborrhea. Often, biopsy is necessary and appropriate to settle the issue, other factors being equal.
TREATMENT/PROGNOSIS
The patient was given a prescription for clobetasol 0.05% ointment for twice-daily application Monday through Friday (and no application for two consecutive days—in this case, the weekend—per week). Studies have established the efficacy and safety of this treatment regimen.
In a month or two, application can be reduced to once or twice a week to control the condition.