Perianal atypical leiomyoma

Rationale: Reports on perianal atypical leiomyoma, a perianal tumor, are rare. We confirmed a perianal atypical leiomyoma by its clinical presentation, magnetic resonance imaging findings, and immunohistochemistry. Patientconcerns:A 28-year-old female with a perianal mass found more than 4 years ago. The 5cm_4cm_4cm sized mass was located on the left side of the anus and vagina; The magnetic resonance imaging (MRI) scan revealed: A 4.1cm 5.2cm 4.9cm sized round mass was observed on the left side of the circumference. Diagnoses: Perianal atypical leiomyoma. Interventions: anal peripheral mass resection was performed under lumbar anesthesia. Outcomes: The postoperative course was uneventful, healing, the patient was discharged. Lessons: Perianal atypical leiomyomas are benign tumors, but with the clinically atypical leiomyoma, it is sometimes difficult to distinguish between potential malignant smooth muscle tumors,and there may be malignant changes. Surgery should ensure complete resection, and to avoid postoperative recurrence, there should be a regular follow-up. Abbreviation: MRI = magnetic resonance imaging.