Case Report: Giant vulvar ulcer caused by Behcet's disease.

Rationale: Behcet's disease (BD) is a chronic, multisystem autoimmune vasculitis that can cause severe genital ulcers. Giant vulvar ulcers (diameter ≥4 cm) secondary to BD pose significant therapeutic challenges due to their refractory nature, risk of functional impairment, and impact on fertility and aesthetic outcomes. Patient concerns: A 19-year-old female presented with a left-sided vulvar ulcer that had persisted for over 4 months and worsened over the preceding 2 months. Diagnoses: The patient was diagnosed with a female vulvar ulcer secondary to Behcet's disease and perineal soft tissue infection based on the 2014 International Criteria for Behcet's Disease (ICBD). Interventions: The patient received intravenous glucocorticoid and antibiotic therapy, followed by pedicled skin flap transplantation, with adjuvant topical Shengji Yuyang ointment for wound care. Outcomes: Following systemic anti-inflammatory therapy, antibiotic treatment, and pedicled flap transplantation combined with topical Shengji Yuyang ointment, the ulcer healed completely within 6 weeks. At 5-month follow-up, no recurrence was observed. However, at month 6, after self-discontinuation of prednisone due to weight gain, a small recurrent ulcer developed, which resolved with topical corticosteroids and oral colchicine. Lessons: Vulvar ulcers secondary to BD may initially appear mild, but if diagnosis and treatment are delayed, they can rapidly progress, leading to extensive tissue destruction and impairment of genital aesthetics and reproductive function. Early identification and intervention are essential. Pedicled flap transplantation, when combined with adequate preoperative wound preparation, can both accelerate ulcer healing and preserve the aesthetic and functional integrity of the affected area.