For more practice Q&A and Board prep study tools—visit DermInReview.comCase Studies authored by our educational partner GW School of Medicine and Health Sciences Dermatology Residency Program.Explanation/Literature ReviewThe clinical and histologic findings are most consistent with erosive lichen planus. This variant of lichen planus (LP) affects the oral and genital mucosa with painful erosions and ulcers. The gingival can also be effected leading to gingivitis and periodontitis. When gingival disease is found together with involvement of the vagina and vulva, the term vulvovaginal-gingival disease has been used. The disease tends to affect middle aged to elderly adults and studies have shown that females are twice as likely to be affected when compared to males. Long term complications can include development of squamous cell carcinoma within the lesions and scarring of genital tissue leading the sexual dysfunction.Of the variants of LP, the oral erosive type is most strongly associated with chronic hepatitis C virus (HCV) infection. A retrospective cross-sectional study from Brazil demonstrated that a statistically significant increase in the number of patients with oral erosive LP patient with HCV seropositivity compared to patients who were seronegative (30% versus 6.38%). Previous studies have also demonstrated the presence of HCV RNA when PCR tests were performed on tissue from oral lesions from 93.8% of seropositive patients. While the exact pathophysiologic process linking HCV infection and oral erosive LP is has not been completely elucidated, it is thought that the infection may produce to antigens that mimic proteins found on keratinocytes and give rise to an autoimmune reaction driven by memory and cytotoxic T-cells against the epidermis. Recently there have been multiple case reports documenting the successful use of direct acting anti-viral therapy against HCV with subsequent improvement or resolution of oral LP in seropositive patients.The correct answer is E: Hepatitis C virusReferences1. Vanzela TN, Almeida IP, Bueno Filho R, Roselino AM. Mucosal erosive lichen planus is associated with hepatitis C virus: analysis of 104 patients with lichen planus in two decades. Int J Dermatol. 2017 Mar 20.2. Shiohara T and Kano Y. “Lichen Planus and Lichenoid Dermatoses.” Dermatology. Ed. Jean L. Bolognia, Ed. Joseph L. Jorizzo, Ed. Julie V. Schaffer. Philadelphia: Saunders, 2012. 183-196. Print.3. Misaka K, Kishimoto T, Kawahigashi Y, Sata M, Nagao Y. Use of Direct-Acting Antivirals for the Treatment of Hepatitis C Virus-Associated Oral Lichen Planus: A Case Report. Case Reports in Gastroenterology. 2016;10(3):617-622.