Aggressive angiomyxoma occurring in the stomach: A case report and review of literature

Abstract

BACKGROUND

Aggressive angiomyxoma (AA) is a rare, slow-growing, locally invasive mesenchymal tumor classified as an undifferentiated neoplasm under the World Health Organization classification system. It predominantly occurs in the vagina, vulva, and other pelvic soft tissues, although its clinical manifestations can be highly variable.

CASE SUMMARY

We report a case of AA located in the lesser curvature of the gastric antrum in a middle-aged female who presented with a palpable abdominal mass of one week’s duration. The patient subsequently underwent en bloc tumor resection, with histological confirmation of the diagnosis of gastric AA. Currently, there are no signs of tumor recurrence, and the patient’s general condition is satisfactory.

CONCLUSION

To our knowledge, this represents the second reported case of gastric-origin AA worldwide. AA arising in the stomach remains difficult to differentiate radiologically, and further clinical data are needed for comprehensive analysis in the future.

Key Words: Aggressive angiomyxoma; Stomach; Computed tomography; Magnetic resonance imaging; Endoscopic ultrasound; Case report

Core Tip: Aggressive angiomyxoma is a rare, slow-growing, locally invasive mesenchymal tumor. We present a case of aggressive angiomyxoma located in the stomach in a female, with a comprehensive review of its imaging features of endoscopic ultrasound, computed tomography, and magnetic resonance imaging.

INTRODUCTION

Aggressive angiomyxoma (AA) is a rare, slow-growing, locally aggressive mesenchymal tumor classified by the World Health Organization as being of uncertain differentiation[1]. AA most frequently occurs in the perineal region of women of reproductive age, but may also arise in the vagina, vulva, and other pelvic soft tissues. However, AA may also develop in males, with a male-to-female prevalence ratio of approximately 1:6[2]. The clinical manifestations of AA are highly variable, ranging from painless masses to nonspecific symptoms such as dyspareunia. Due to its rarity, AA is often misdiagnosed as other conditions, including lipomas, Bartholin gland cysts, and hernias.

AA can occur in extrapelvic and extraperineal sites, such as the larynx[3], maxilla[4], floor of the mouth[5], scrotum[6], prostate[7], thigh[8], axilla and chest wall[9], lung[10], and jejunum[11]. Gastric origin of AA is exceptionally rare, and to our knowledge, the case we report here represents the second documented instance worldwide[12].

We present a case of AA localized to the stomach in a female, with a comprehensive review of its endoscopic ultrasound (EUS), computed tomography (CT), and magnetic resonance imaging (MRI) features.

CASE PRESENTATION

Chief complaints

A 48-year-old female presented to our hospital with “recurrent epigastric pain for several years, recurrent with nausea after consuming large amounts of cold beverages and grilled fish for 13 days”.

History of present illness

Thirteen days prior to admission, the patient developed severe epigastric pain with nausea after consuming large amounts of cold beverages and grilled fish, prompting emergency evaluation.

History of past illness

Over the past several years, the patient experienced recurrent epigastric pain triggered by improper diet or fasting, without associated diarrhea, vomiting, or gastrointestinal bleeding. Repeated gastroscopies in 2021 and 2024 revealed multiple small polyps in the gastric body and shallow duodenal ulcers. Laboratory investigations during this period showed an erythrocyte sedimentation rate of 34 mm/hour, with no other significant abnormalities.

Personal and family history

The patient had no significant medical history of chronic diseases (e.g., hypertension or diabetes) and no significant family history.

Past medical history

Past medical history was non-contributory, including no history of surgery, trauma, or infectious diseases.

Physical examination

Physical examination findings were unremarkable.

Laboratory examinations

Emergency laboratory tests revealed an elevated high-sensitivity C-reactive protein level of 19.77 mg/L. Other parameters, including the complete blood count and erythrocyte sedimentation rate, were unremarkable.

Imaging examinations

Contrast-enhanced abdominal CT demonstrated irregular thickening of the gastric antral wall with heterogeneous enhancement. A cystic lesion (3.4 cm × 2.2 cm) was found adjacent to the lesser curvature of the gastric antrum, exhibiting thick-walled morphology, blurred margins, and mild enhancement post-contrast (Figure 1). Two omental nodules near the inferior liver margin and enlarged lymph nodes in the hepatogastric ligament and mesentery were observed. MRI revealed an abnormal signal lesion (2.8 cm × 1.5 cm) lateral to the lesser curvature of the gastric antrum, showing hyperintensity on T1 weighted imaging (T1WI) (Figure 2), hypointensity on T2 weighted imaging (T2WI) (Figure 2), and no enhancement post-contrast (Figure 2). The vertical-axis ultrasound gastroscopy scan shows a uniform echo in the gastric body. A low-echo mass-like change approximately 3.0 cm × 2.2 cm in size is observed on the outer wall of the gastric antrum (Figure 3), with uneven internal echoes and visible high-echo structures (Figure 3). Based on the imaging findings, a hematoma or inflammatory lesion was suspected, with malignancy not excluded.

Figure 1 On computed tomography scanning, a cystic lesion is observed outside the lesser curvature wall of the gastric antrum, measuring approximately 3.0 cm × 2.2 cm. A: After contrast enhancement, mild enhancement is noted at the periphery of the lesion, represents the non-contrast computed tomography (CT) scan phase; B: Represents the arterial phase of the CT scan; C: Represents the venous phase of the CT scan. The lesion exhibits thick-walled changes with blurred margins.

Figure 2 Magnetic resonance imaging findings show an abnormal signal focus on the outer gastric wall of the lesser curvature of the antrum. A: The lesion shows a slightly hypointense signal on T1-weighted imaging; B: The lesion appears hyperintense, and on T2-weighted imaging; C: On T1-weighted images, the lesion is approximately 3.0 cm × 2.2 cm in size, with peripheral enhancement after contrast administration; D: On Diffusion-weighted imaging (DWI) sequence, the lesion shows a hyperintense signal at the edge. A: Magnetic resonance imaging (MRI) T1; B: MRI T2; C: MRI T1 with contrast enhancement; D: MRI DWI.

Figure 3 The vertical-axis ultrasound gastroscopy scan shows a uniform echo in the gastric body. A: Low-echo mass-like change approximately 3.0 cm × 2.2 cm in size is observed on the outer wall of the gastric antrum, with uneven internal echoes and visible high-echo structures; B: Lesion size measured by ultrasound.

FINAL DIAGNOSIS

The final diagnosis of AA was established based on the surgical pathology findings.

TREATMENT

Laparoscopic resection of the abdominal masses and adhesiolysis were performed. Gross pathology showed a well-circumscribed, encapsulated tumor with a raised surface. Histopathology demonstrated spindle cells dispersed within a myxocollagenous stroma. Immunohistochemistry findings showed positive cytokeratin (pan) (+), desmin (+), cluster of differentiation (CD) 34 (vascular +), β-catenin (cytoplasmic +), H3K27Me3 (+), RB1 (+), CD68 (scattered +), endoplasmic reticulum (focal +), Fli-1 (vascular +), CD31 (vascular +), and INI-1 (+); and negative CD117 (-), S-100 (-), smooth muscle actin (-), DOG-1 (-), ALK (-), SOX10 (-), STAT6 (-), EMA (-), NTRK (-), mesothelin (-), calretinin (-), TFE3 (-), and PR (-).

OUTCOME AND FOLLOW-UP

The patient underwent uneventful surgery and was discharged on postoperative day 2. Follow-up contrast-enhanced abdominal CT at 3 months showed no evidence of recurrence, and the patient is currently in a stable condition.

DISCUSSION

AA is a rare mesenchymal tumor that is classified as an aggressive tumor due to its local invasiveness and high recurrence rate despite its slow growth. AA most commonly presents in the perineal-pelvic region of premenopausal women and in the inguinal scrotal region of men[13,14]. The tumor may present in various sizes and shapes and easily invade surrounding tissues, but rarely invades the rectum, vagina, or urethra, so there are no specific symptoms, and it may only present as a visible perineal and vulvar mass[15]. However, patients may experience nonspecific symptoms due to mass effect, such as pelvic fullness, vulvar or perineal pain, or dyspareunia. As AA is rare and has a cystic appearance, it is often misdiagnosed as a cyst, hernia, lipoma, or cancerous lesion[16,17]. The pathogenesis of AA is still unclear. Studies have shown that there is a translocation at the level of chromosome 12, which leads to abnormal expression of the high mobility group protein subtype I-C involved in DNA transcription[18].

Usually, AA lesions are discovered through imaging examinations after consultation, so it is particularly important to identify AA during imaging. In the past, scholars have studied the manifestations of AA on CT, MRI, and B-ultrasound. Five female patients with AA underwent CT and MRI studies, which showed a well-defined mass that displaced adjacent structures. The tumor had low attenuation relative to muscle on CT. On MRI, the tumor was isointense relative to muscle on T1WI, hyperintense on T2WI, and enhanced after gadolinium contrast with a characteristic “whorl” internal pattern. MRI demonstrated the extent of the tumor and its relationship to the pelvic floor. The appearance of recurrent tumors was similar to that of the primary lesion[19].

On MRI, AA is hypodense relative to muscle and appears layered or swirling after contrast injection. AA is isointense relative to muscle on T1WI and hyperintense on T2WI, which is enhanced after gadolinium injection, indicating rich blood vessels. The tumor fibrovascular stroma is enhanced, showing a characteristic layered or swirling appearance[20].

AA may be identified on enhanced CT or MRI due to the characteristic internal structural features on contrast-enhanced CT or T1-weighted MRI, namely “swirling”, and the low-signal band structure of fibrovascular tissue can also be shown on T2WI. However, compared with CT, MRI can show the margins of the tumor relative to the surrounding structures, especially the dynamic contrast-enhanced sequence, so it is more helpful for preoperative assessment of the scope of surgery[21].

In this case, AA grew outside the gastric wall, and no characteristic “whirlpool” pattern was seen on CT and MRI. In addition, AA showed cystic lesions on CT, without the characteristic whirlpool sign of AA in the perineum. Therefore, we speculate that the previous typical AA imaging findings cannot be used for AA in rare sites such as the gastric wall.

In our case, we showed the image of AA under ultrasound gastroscopy for the first time, where low-echo mass-like changes outside the gastric antrum wall, uneven internal echoes, and high-echo structures were seen. This is different from the imaging manifestations of AA with medium-high echoes and rich blood vessels[22,23] under conventional percutaneous B-ultrasound. This may also suggest that the ultrasound images of AA in rare sites and those in common sites may be different.

AA is a benign tumor that usually grows slowly, has a tendency to local invasion and recurrence, but has a good overall prognosis and is rarely life-threatening[21]. Distant metastasis and even death are rarely reported[24-26].

When feasible, surgical resection is the most effective treatment for AA, but local lesions are prone to recurrence. However, if conditions permit after local recurrence, local surgical resection of the recurrence can still be performed[27]. Therefore, it is very important to evaluate the extent of the tumor through imaging examinations before surgery. In addition, gonadotropin-releasing hormone agonists (GnRH-a) can be used before surgery to reduce the size of the tumor and prevent postoperative recurrence. For patients who are unwilling to accept or cannot tolerate surgical treatment, GnRH-a alone can be tried[28]. In male patients, if the androgen receptor (AR) is positive, AR blocking drugs (bicalutamide) can be used to achieve long-term lesion remission[29]. In addition to surgery and hormone therapy after lesion recurrence, studies have reported that local radiotherapy[30] and local chemical ablation with anhydrous ethanol and glacial acetic acid[31] can also be safe and effective for the treatment of residual or recurrent AA.

CONCLUSION

In summary, AA remains a condition prone to misdiagnosis, especially when it occurs in atypical locations such as non-perineal areas. Preoperative imaging remains the primary method for identifying the lesion. Although CT and MRI exhibit characteristic findings, the imaging manifestations of AA in non-typical locations remain atypical. The EUS features of AA occurring in the stomach also require further case accumulation for a more comprehensive understanding. Surgery remains the primary treatment modality. Postoperative follow-up with regular imaging is necessary to assess possible recurrence.