Clinicopathological features and differential diagnosis of aggressive angiomyxoma of the female pelvis: 5 case reports and literature review

Abstract

Aggressive angiomyxoma (AAM) is a rare mesenchymal tumor that usually occurs in the pelvis and perineum of young females. AAM can simulate Bartholin's gland cyst, abscess, lipoma, simple labial cyst, or other pelvic soft tissue tumors. Here we present five cases of AAM with mean age of 42. The patients mainly presented slow-growing mass in the abdomen and perineum (3 cases in the pelvis, 1 in the vulva, and 1 in the buttock). Color Doppler flow imaging revealed blood flow for the 3 pelvic lesions. Enhanced computed tomography and magnetic resonance imaging of the other 2 cases showed the typical "swirled" or "layered" structure characteristic. Through the pathological examination, its positivity to estrogen and progesterone receptors can justify enlargement and recurrence, confirming the tumor is AAM. All 5 patients underwent local tumor resection. Two patients recurred 8 and 15 months after surgery, respectively. The longest follow-up was 42 months. Although few cases are reported, early recognition demands high index of suspicion for both gynaecologists and pathologists. Wide surgical excision with tumor free margins is the basis of curative treatment. Adjuvant therapy may be necessary for residual or recurrent tumors. Long-term follow-up is recommended.

Figure 1

B-ultrasound showed that (A) case 1, pelvic mass with visible internal blood flow signal; and (B) case 2, irregular mass in the left buttock with a clear border. (C) Case 4, sagittal magnetic resonance imaging (MRI) shows a pelvic irregular mass (7 × 4.4 × 3 cm) on T2WI MRI. DWI sequence shows a moderately high signal. (D) Case 4, axial MRI showing heterogeneous enhancement. A “layered” structure can be observed. DWI = diffusion weighted image, T2WI = T2 weighted image.

Figure 2

HE staining of tumor and observation under a microscope. (A) Tumor cells were distributed sparsely and scattered in the acidic mucin-rich matrix in the shape of stellate or spindle (magnification × 200). (B) The cytoplasm of the tumor cells was lightly stained with poorly defined borders. The nuclei were oval-shaped with a single, small nucleolus. No mitotic structures were seen (magnification × 400). (C) The myxedematous stroma contained varying numbers of blood vessels with medium caliber and evidently dilated vessels (arrows, magnification × 200). (D) The tumor invaded into the surrounding striated muscle (arrows, magnification × 200). HE = hematoxylin-eosin staining.

Figure 3

Tumor immunohistochemistry. (A) The tumor cells were positively stained for desmin with the EnVision method (magnification × 200). (B) The tumor cells were partly positively stained for smooth muscle actin with the EnVision method (magnification × 200). (C) The positive rate of estrogen receptor in tumor cells was about 80%, as shown by the EnVision method (magnification × 200). (D) The positive rate of Ki-67 in tumor cells was about <3%, as shown by the EnVision method (magnification × 200).