Aggressive (Deep) Angiomyxoma of the Female Pelvis and Perineum Presenting as a Large Pelvic Organ Prolapse

Aggressive angiomyxoma (AA) is a rare, benign but locally invasive mesenchymal tumor arising from myxoid connective tissue, predominantly affecting women of reproductive age. Its clinical presentation is often nonspecific, frequently mimicking other pelvic or perineal pathologies, which leads to delayed diagnosis. We report an exceptional case of AA presenting as a massive, irreducible pelvic organ prolapse. A healthy multiparous woman in her 40s presented to a Urogynecology Consultation with a 6-year history of a progressively enlarging perineal mass, initially interpreted as a complete pelvic organ prolapse. She reported no pain or systemic symptoms. Clinical examination revealed a large, irreducible perineal mass measuring approximately 30 cm, resembling a fourth-degree uterovaginal prolapse. Pelvic magnetic resonance imaging demonstrated a volumous heterogeneous mass extending from the umbilical region and prolapsing through the perineum. A percutaneous biopsy revealed a mesenchymal neoplasm with smooth-muscle differentiation, initially suggestive of a pelvic leiomyoma. No metastatic lesions were detected on chest computed tomography. The patient underwent wide local excision of the tumor, total hysterectomy, and anterior rectal resection with a temporary colostomy. Histopathological examination confirmed the diagnosis of aggressive angiomyxoma. The postoperative course was uneventful, and intestinal continuity was later restored. The patient remains asymptomatic and disease-free under regular follow-up. This case highlights the diagnostic challenge posed by aggressive angiomyxoma due to its slow growth, deep pelvic location, and clinical resemblance to more common urogynecologic conditions such as pelvic organ prolapse or leiomyoma. MRI remains the imaging modality of choice for preoperative assessment, while complete surgical excision with clear margins is the mainstay of treatment. Given its high recurrence potential, long-term follow-up is essential. Awareness of this rare entity is crucial for early recognition and appropriate multidisciplinary management.