Photo Rounds

White macules on knee

A 14-year-old girl presented to Dermatology with white, confetti-like, slightly atrophic macules on her left knee and lateral leg. She said the lesions had been there for 3 months. Her family was concerned about an autoimmune disease, as they were aware that it could cause light patches on the skin.

What’s your diagnosis?


 

References

White macules on knee

The ivory white appearance and slight atrophy of the lesions raised the possibility of extragenital lichen sclerosus (LS). A 4-mm punch biopsy confirmed the diagnosis.

LS occurs in all races and is an uncommon, chronic inflammatory disease that most often affects the vulva and perianal mucosa in postmenopausal women.1 That said, it can also affect men and children, and manifest in places such as the trunk and neck. Extragenital lesions may appear ivory white, as in this case, or may resemble ecchymoses and raise alarm for possible abuse.

When LS is present on the extremities, a complete skin surface exam, including external genitalia, is warranted. LS is thought to be an autoimmune disease and is associated with vitiligo, autoimmune thyroid disease, and morphea.

In cases of suspected LS, it’s important to biopsy the full thickness of the skin and subcutaneous tissue. It is helpful to include an area of normal skin in the sample, as the findings are subtle and best contrasted with the architecture of unaffected skin. For this patient, a 4-mm punch biopsy was sufficient, but an incisional biopsy would be more appropriate for a larger patch or plaque.

Treatment options are based on a small case series and a few small randomized controlled trials. Medications include topical steroids, topical calcineurin inhibitors, systemic retinoids, and topical estrogens.

In this case, the patient was advised to apply topical clobetasol 0.05% cream bid to the affected area for 2 weeks, then twice weekly for 4 weeks. She had partial clearance with this approach, but small macules later appeared on her dorsal foot; the treatment was repeated.

Text and photos courtesy of Jonathan Karnes, MD, medical director, MDFMR Dermatology Services, Augusta, ME. (Photo copyright retained.)

Recommended Reading

Tofacitinib: Small study shows big cutaneous sarcoidosis response
MDedge Family Medicine
Debate: Should biologics be used for milder cases of psoriasis?
MDedge Family Medicine
Psoriasis associated with an increased risk of COVID-19 in real-world study
MDedge Family Medicine
TNF inhibitors linked to threefold increased risk of psoriasis in JIA patients
MDedge Family Medicine
LGBTQ patients face unique skin risks
MDedge Family Medicine
Multidisciplinary approach touted for atopic dermatitis
MDedge Family Medicine
Brown plaque on the arm
MDedge Family Medicine
Atopic dermatitis genes vary with ethnicity
MDedge Family Medicine
AAD unveils new guidelines for actinic keratosis management
MDedge Family Medicine
Genital skin exams in girls: Conduct with care, look for signs of abuse
MDedge Family Medicine