Case Report of an Aggressive Angiomyxoma Presenting as Pelvic Organ Prolapse

Abstract

Aggressive angiomyxoma (AAM) is a rare, slow‐growing, locally infiltrative mesenchymal tumor of the pelvis and perineum, most often affecting women. Its nonspecific presentation and tendency to mimic more common vaginal or periurethral masses frequently delay diagnosis. Early recognition is critical to guide appropriate surgical planning, optimize resection, and reduce recurrence risk. In this case, a 61‐year‐old woman with prior vaginal hysterectomy presented with symptoms of pelvic organ prolapse, urinary incontinence, and occasional bleeding. Examination revealed a 10 × 3‐cm protruding anterior vaginal wall mass with a spongy texture. MRI demonstrated a well‐defined tubular lesion in the left distal vaginal wall extending towards the vulva. Intraoperative evaluation, including cystourethroscopy, diagnostic laparoscopy, and general surgery consultation, ruled out bowel involvement. The mass was excised via vaginal approach with preservation of surrounding structures. Histopathology confirmed AAM. Margins could not be assessed due to specimen disruption. At 6‐week follow‐up, the patient was asymptomatic with well‐healed incisions, and ongoing surveillance with gynecologic oncology was arranged. This case highlights the importance of including AAM in the differential diagnosis of anterior vaginal wall masses. Multidisciplinary collaboration and advanced imaging are essential for accurate diagnosis and surgical planning. Given the tumor′s locally infiltrative nature and high recurrence rate, long‐term follow‐up is warranted. Awareness of this rare pathology can aid timely recognition and improve patient outcomes.

1. Introduction

Anterior vaginal wall and periurethral masses are relatively uncommon, with an estimated prevalence of approximately 1%–4% in the general female population [1, 2]. The most frequent benign etiologies include urethral diverticula and Skene gland cysts or abscesses [1]. Malignant causes are rare, comprising approximately 1.6% of such masses [1, 3]. Evaluation of an anterior vaginal wall mass must include a broad differential diagnosis, comprising both common and rare conditions. Such a differential may include but is not limited to anterior compartment prolapse, urethral diverticulum, Gartner duct cyst, Skene gland cyst, Bartholin′s cyst, ectopic ureterocele, hemangioma, and prior bulking material. Benign and malignant tumors may include lipoma, fibroma, leiomyoma, angiomyxoma, leiomyosarcoma, lymphoma, and melanoma [1, 2, 4, 5]. Aggressive angiomyxoma (AAM) is a rare, slow‐growing, and locally invasive mesenchymal tumor primarily affecting the pelvis and perineum of adult women [3]. Risk factors include female sex, premenopausal age (30s–40s), and high levels of hormone receptors (estrogen/progesterone). First described by Steeper and Rosai in 1983, AAM is characterized by its aggressive nature and high propensity for local recurrence, despite its benign histological appearance. This tumor is notably challenging to diagnose preoperatively due to its nonspecific clinical presentation and its tendency to mimic other more common pelvic and perineal masses.

The exact etiology and pathogenesis of AAM remain unclear, though hormonal influences have been suggested due to its prevalence in women of childbearing age and occasional expression of estrogen and progesterone receptors [6]. Clinically, AAM presents as a slow‐growing, painless mass that can reach considerable size before detection, often due to its deep location and lack of early symptoms. Imaging modalities such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) play a critical role in preoperative assessment. MRI findings typically include marked T2 hyperintensity, a laminated appearance (“swirl” pattern), and infiltrative margins, but are not always identified. Definitive diagnosis typically requires histopathological examination [7]. Histopathologically, AAM is characterized by a myxoid stroma rich in collagen and hyaluronic acid, and a sparsity of spindle and stellate cells [8]. Immunohistochemical staining is usually positive for desmin, smooth muscle actin, and vimentin, aiding in its differentiation from other soft tissue tumors.

Surgical excision with clear margins is the mainstay of treatment for AAM [9–11]. However, achieving complete resection is often challenging due to the tumor′s infiltrative nature and anatomical location. Recurrence rates are high, reported between 30% and 70% [8, 12], necessitating vigilant long‐term surveillance. Adjunctive therapies, including hormonal manipulation with gonadotropin‐releasing hormone (GnRH) agonists and radiotherapy, have been explored, particularly in cases where surgery is not feasible or in recurrent disease [13–15].

This case report contributes to the existing literature by documenting a unique case of AAM presenting as a vaginal mass and underscores the necessity of a multidisciplinary approach in managing this rare entity, from an index of suspicion for AAM in preoperative diagnosis and effective surgical planning to postoperative follow‐up for mitigating the risk of recurrence.

2. Case Presentation

A 61‐year‐old female with a history of vaginal hysterectomy for abnormal uterine bleeding (leiomyoma) 10 years prior to presentation and hidradenitis suppurativa (HS) presented with symptoms of pelvic organ prolapse, including a vaginal bulge noted while wiping, urinary incontinence, and occasional bleeding from HS lesions. The vaginal bulge was especially prominent during defecation. A prolapsing vaginal mass measuring approximately 10 × 3 cm arising from the left anterolateral vaginal wall was noted at a general gynecology visit, and the patient was referred to urogynecology for further evaluation. During an office consultation with urogynecology, the patient had a notable protrusion of the anterior vaginal wall. On palpation, the mass was tubular in appearance with a spongy texture, inconsistent with a cyst (see Figure 1). An MRI was performed, which confirmed the presence of a well‐defined 9 × 1.5‐cm tubular structure in the left distal vaginal wall, extending inferiorly towards the left vulva. An obstructing process such as a complicated fluid collection/abscess or complicated cyst could not be excluded based on the MRI report. Selections from the patient′s MRI can be seen in Figure 2. The patient underwent consultation with gynecologic oncology. They had low suspicion for malignancy based on examination and imaging studies, and did not recommend preoperative biopsy. She opted to have surgical management with urogynecology independently.

Figure 1.

Patient′s preoperative examination with anterior vaginal wall mass protruding through the introitus and mimicking anterior compartment prolapse.

Figure 2.

Magnetic resonance images. Coronal view with notable tubular structure measuring 9 × 1.5 cm (blue arrow) in the region of the left distal vaginal wall and extending inferiorly towards the left vulva.

After informed consent, the patient was taken to the operative suite. An exam under anesthesia and an unremarkable cystourethroscopy were performed. A urethral catheter was placed easily. Given concern for an intra‐abdominal process, a diagnostic laparoscopy was performed, which revealed filmy adhesions of the small bowel near the bladder. Adhesiolysis was performed, general surgery was consulted intraoperatively, and no protrusion of small bowel/enterocele into the mass was confirmed. Attention was then turned to the vagina, where a vertical incision was made in the vaginal mass after vasopressin infiltration, and the mass was dissected off the vaginal epithelium with electrocautery and sharp dissection. The mass was excised from its base, and hemostasis was achieved with sutures. The excess vaginal epithelium was trimmed, and the incision was closed with a running, locked, absorbable suture of polyglactin 910 (Vicryl). A repeat cystourethroscopy showed no injury to the bladder or urethra, and bilateral ureteral efflux was confirmed. Hemostasis from prior adhesiolysis was confirmed laparoscopically. The patient was discharged home on the same day after an unremarkable recovery in the postanesthesia care unit.

At 6 weeks postoperatively, the patient was feeling well with no complaints. Her prior complaint of urinary incontinence had completely resolved. Her vaginal exam demonstrated well‐healed incisions with good apical, anterior, and posterior support. Pathology reported gross findings of blue‐gray, rubbery, and intact fibromembranous soft tissue, as well as a tan‐pink, smooth, disrupted cystic wall, with a final pathologic diagnosis of deep AAM measuring 14.5 × 4.5 × 2.6 cm. Margins were not evaluated due to insufficient orientation and disruption of the specimen. Sections show a neoplasm composed of hypocellular and weakly myxoid stroma, remarkable for delicate collagen fibrils and variably sized blood vessels, with occasional perivascular clustering of smooth muscle cells and collagen bundles (Figure 3). Cytologically, the stellate tumor cells have uniform, bland nuclei and scant eosinophilic cytoplasm. Immunophenotypically, the lesional cells are positive for desmin and ER, whereas negative for S100 and CD34. An Alcian blue special stain highlights the weakly myxoid stroma. The patient was scheduled for follow‐up with gynecologic oncologist, who did not recommend further surgical exploration at this time, and continues to follow with serial pelvic exams and yearly MRI imaging.

Figure 3.

Sections show hypocellular and weakly myxoid stroma remarkable for variably sized blood vessels and delicate collagen fibrils (A; H&E, 4X). Cytologically, the stellate tumor cells have uniform bland nuclei and scant eosinophilic cytoplasm (B; H&E, 20X). Immunophenotypically, the lesional cells are positive for estrogen receptor (D; 10X) and desmin (E; 10X). Alcian blue (C; 10X) special stain highlights weakly myxoid stroma.

3. Discussion

AAM is a distinctive yet rare soft tissue tumor that predominantly affects the pelvic and perineal regions of women. The case of an AAM arising in the vagina presented here is rare and highlights important multidisciplinary considerations in the diagnosis and management of this condition. What makes this case particularly unique is the patient′s postmenopausal status. AAM classically occurs in premenopausal women between the third and fifth decades of life and is frequently associated with estrogen and progesterone receptor expression, suggesting hormonal responsiveness. In contrast, presentation in postmenopausal women is even less common, and the number of reported cases in the literature is scarce [16, 17].

This case therefore broadens the clinical spectrum of AAM and highlights that the diagnosis should still be considered in postmenopausal women presenting with atypical anterior vaginal wall masses or prolapse‐like symptoms. In our patient, the lesion clinically mimicked anterior compartment prolapse and was initially difficult to characterize on imaging, further emphasizing the diagnostic challenge associated with this tumor. Unlike the classic MRI description of infiltrative margins and a characteristic “swirl sign,” imaging in this case demonstrated a tubular structure that was initially interpreted as a possible complicated cystic lesion or fluid collection. This atypical appearance underscores the importance of maintaining a broad differential diagnosis, particularly when examination findings are inconsistent with common benign entities.

Strengths of this case included the multidisciplinary approach involving gynecologic oncology and general surgery, which facilitated comprehensive evaluation and management. Additionally, the strategic use of advanced imaging helped narrow the differential diagnosis and guide surgical planning. However, the specimen was not marked at its proximal end; thus, margins could not be evaluated. Had AAM been included in our differential, we would have marked the proximal end to aid in assessment of margins, which helps in the management of this locally invasive tumor. In future cases, marking the specimen is recommended. A limitation of this case report is that given the rarity and variable clinical presentation of AAM, diagnosis remains challenging and often delayed, limiting the generalizability of any single case.

The management of AAM benefits from a multidisciplinary approach, involving gynecologists, radiologists, pathologists, and oncologists. This collaborative effort is essential for accurate diagnosis, effective treatment planning, and comprehensive follow‐up care. Given the tumor′s rarity and potential for significant morbidity due to local invasion and recurrence (though typically benign), it is crucial to enhance awareness and understanding of AAM among urogynecologists, who are poised to receive referrals regarding vaginal “cysts” or “masses” in older patients. Further research into the pathogenesis, optimal management strategies, and the role of adjunctive therapies for AAM is warranted to improve outcomes for affected patients.

Funding

No funding was received for this manuscript.

Conflicts of Interest

The authors declare no conflicts of interest.

Ramstein, Joris , Ter Haar, Charlotte , Guaderrama, Noelani , Alrwashdeh, Audai , Lee, Jennifer , Case Report of an Aggressive Angiomyxoma Presenting as Pelvic Organ Prolapse, Case Reports in Obstetrics and Gynecology, 2026, 6017372, 4 pages, 2026. 10.1155/crog/6017372

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.