LAUSR

Abstract Rationale: Smooth muscle tumors of the vulva are infrequent neoplasms with diverse histologic features and unclear biologic behavior. Herein, we report a very rare case of vulvar epithelioid leiomyoma and review of previous reported cases of these tumors. In addition, we have discussed the representative diagnostic criteria of vulvar smooth muscle tumors and prognostic significance of epithelioid morphology. Patient concerns: We recently met a 45-year-old woman with complaint of painful vulvar mass. Interventions: Excisional biopsy was performed. Diagnoses: Pathologic examination revealed a vulvar epithelioid leiomyoma with multinodular growth pattern. Mitotic activity was rare and cellular atypia was not identified. Based on histology and immunohistochemical staining results, the case was diagnosed as vulvar epithelioid leiomyoma. Outcomes: After mass excision, the patient was discharged with no complication and there was no evidence recurrence for 6 months. Lessons: After reviewing previous papers and diagnostic criterion, we thought that vulvar smooth muscle tumors with predominant epithelioid morphology may be associated with unfavorable prognosis, Therefore, pathologists should examine the epithelioid component in vulvar smooth muscle tumors carefully.