Giant perianal angiomyofibroblastoma--a case report.

A 45-year old female had a long history of slow growing perianal tumor at the right side of her anus. Encapsulated tumour was found intraoperatively and completely excised using the Harmonic Scalpel. Tumour was well-circumscribed and relatively firm; measuring 12x6x4 cm. Histologically it was composed of oval to spindle cells with minimal nuclear atypia, set in mucous matrix with numerous thin-walled blood vessels. Immunohistochemically, expression of smooth-muscle actin and desmin, as well as estrogen and progesterone receptor were found in the tumour cells. The diagnosis of angiomyofibroblastoma was established. This rare benign tumour typically involves vulvovaginal, pelvic and perinal region. It is important to separate this neoplasm from locally invasive aggressive angiomyxoma and low grade fibromyxoid sarcoma, which can arise in the the same localisation. The patient was discharged on the third postoperative day and no recurrence was noted in 18 months follow-up.