Aggressive angiomyxoma in pregnancy: A rare and commonly misdiagnosed entity

Introduction

Aggressive angiomyxoma (AAM) is a rare mesenchymal neoplasm of vulvo-perineal region and usually found in women of reproductive age group.[1] It is a slow-growing, low-grade neoplasm but is locally infiltrative, and relapse has been reported in about 30%–40% of cases even after many years of complete resection.[2] Rarely, AAM can metastasize to lungs, peritoneum, and lymph nodes.[3]

Only a few cases of AAM coexistent with pregnancy are reported in medical literature.[45] AAM grows to a huge size during pregnancy which may be due to its hormone dependency as suggested by estrogen receptor and progesterone receptor (PR) positivity.[6] AAM may be clinically misdiagnosed as Bartholin cyst, lipoma, labial cyst, Gartner's duct cyst, levator hernia or sarcoma, and condyloma lata, and rate of misdiagnosis is as high as 80%.[7]

Case Report

A 24-year-old, 17-week pregnant female (G₂P₁L₁), married for 5 years, presented with bleeding per vagina for 3 days. She also complained of huge mass coming out of vagina, difficulty in walking, and pain in abdomen and lower back. There was no history of fever, weight loss, trauma, bowel or bladder disturbance, and use of any contraceptive. Her menstrual history and past history were unremarkable. Local examination showed a large pedunculated, well-circumscribed, ulcerated mass coming out of the vagina.

Ultrasound of abdomen showed bulky anteverted uterus, measuring 9.6 cm × 7.6 cm × 5.4 cm. Prominent heterogeneous endometrium (25 mm) with few small echogenic foci and small pockets of collection were favoring retained products of conception. Furthermore, there was a large solid mass measuring 11.4 cm × 11.3 cm × 9.95 cm in the cervical region, protruding into and outside the vagina. On magnetic resonance imaging, the mass exhibits hyperintense signal on T₂ and hypointense on T₁ with multiple specks of T₁ hyperintensity within, suggestive of pedunculated prolapsed fibroid [Figure 1a].

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Figure 1

(a) Magnetic resonance imaging: mass exhibits hyperintense signal on T₂ and hypointense signals on T₁ with multiple specks of T₁ hyperintensity. (b) Photograph showing solid, homogeneous gray-white mass with glistening appearance

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A clinical diagnosis of spontaneous incomplete abortion with prolapsed cervical fibroid was made, considering that pedunculated mass was excised and uterine curettage was done. Histology of curettage material revealed chorionic villi and trophoblastic tissue. On gross examination, mass was soft to firm and external surface shows congestion. Cut surface was a solid, homogeneous gray-white mass with glistening appearance [Figure 1b]. On microscopy, the tumor composed of admixture of loose fibroareolar tissue with numerous variable-sized vessels and round-to-stellate reticulum cells on myxoid background. Surface was partly lined by stratified squamous epithelium of vagina with areas of ulceration, hemorrhage, and mixed inflammatory cell infiltrate [Figure 2a and b]. On immunohistochemistry, tumor was positive for ER and vimentin [Figure 2c and d] and negative for PR and S-100.

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Figure 2

(a and b) Photomicrographs showing tumor composed of admixture of loose fibroareolar tissue with numerous variable-sized vessels and stellate reticulum cells on myxoid background (H and E, ×40). (c) Photomicrograph showing positive nuclear staining for estrogen receptors in immunohistochemistry. (d) Photomicrograph showing positive nuclear staining for vimentin in immunohistochemistry

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Discussion

AAM was first described by Steeper and Rosai in 1983.[1] The term “aggressive” denotes its propensity for local aggression and recurrence after excision even with negative margins.[8] Sometimes, in view of operative morbidity, partial excision may be done. On computed tomography (CT), AAM has well-defined margins with attenuation less than that of muscle. The attenuation on CT scan and high signal intensity on magnetic resonance imaging are likely to be related to the high water content and loose myxoid matrix of AAM.[5] Superficial angiomyxoma, angiomyofibroblastoma, cellular angiofibroma, and smooth muscle tumor should also be considered as its differential diagnosis. AAM has thick-walled vessels which are less numerous than thin-walled vessels in angiofibroblastoma. Cells of AAM express vimentin, desmin, and smooth muscle antigen and may express estrogen and PRs but are negative for S-100.[9] Hormonal manipulation with tamoxifen, raloxifene, and gonadotropin-releasing hormone agonist analogs has been attempted. These have been shown to reduce the size of tumor and may help in complete excision and in the treatment of recurrence. A gene in the region 12q13–15, called high-mobility group protein isoform I-C (HMGI-C), which encode protein involved in the transcription, has a role in pathogenesis of this tumor. Detection of HMGI-C using immunohistochemistry with anti-HMGI-C antibody may potentially be a useful marker for microscopic residual disease.[10]

Conclusion

When pregnant female presents with painless, soft vulvo-perineal mass, a high index of suspicion for AAM should always be kept in mind. Diagnosis is not at all clinical; thus, cases may present as pedunculated, prolapsed cervical fibroid. Due to its high rate of local recurrence, wide local excision and long-term follow up are necessary.