Anal leiomyoma: a case report

Objective: To present the clinical characteristics, diagnostic study and treatment of a patient with a perianal mass, ultimately diagnosed as a leiomyoma. Clinical case: 43-year-old female patient, who consulted because of discomfort and a non-bleeding perianal mass found 3 months prior that had been treated as inflamed hemorrhoids. Upon examination by a specialist, a nodule measuring 3 x 3 x 3 cm, with semi-solid consistency and no inflammatory signs, stands out in the right lateral perianal area. The MRI shows a solid tumor adjacent to the external anal sphincter. The colonoscopy did not reveal intraluminal lesions. Surgical procedure: right lateral perianal incision, surrounding and completely resecting the tumor. The patient was discharged the next day. Results: Pathological report: Well-defined tumor composed by fused cells with oval-elongated nuclei, blunt edges and small amount of eosinophilic cytoplasm, arranged as disorganized fascicles intertwined in a fibrous stroma. Histochemical study: desmin: positive, DOG1: negative, S100: negative; confirming the diagnosis of this leiomyoma. After a 2-year follow-up, no clinical or radiological recurrence is observed. Conclusion: This case displays the need to consider differential diagnoses in patients with a perianal mass that do not respond to classic treatment.