Aggressive angiomyxoma

Clinical History

32 year old female presented to us with a painless swelling in the perineum for the last 1 year with no history of pain or bleeding. Local examination revealed a solitary pedunculated lesion, soft in consistency, mobile with normal overlying skin, about 10 x 12 cm involving Right labia.

Imaging Findings

Contrast enhanced MR imaging revealed a well-defined pedunculated mass about 14 x 7 x 6 cm arising from the right labia. Mass was hyperintense on T2-weighted images ( Figure 1, 2), iso to hypointense to muscle on T1-weighted images (Figure 3), and showed intense enhancement after administration of gadodiamide (Omniscan, GE Healthcare ) (Figure 4, 5, 6 ). A whorled pattern of signal intensity on T2-weighted images was noted. The lesion appeared to be displacing rather than infiltrating the adjacent soft tissue. Computed tomography angiogramm revealed prominent pudendal artery supplying the lesion, ( Figure 7, 8) The urogenital diaphram appeared normal. The mass was surgically excised and was proved to be an aggressive angiomyxoma at histologic analysis.

Discussion

Aggressive angiomyxoma (AA) are uncommon mesenchymal tumors with a predilection for the pelvis and perennial regions in females and less frequently in males, most commonly in the 3rd–5th decades of life. They usually present as a visible mass, may include discomfort from the mass, or pressure effects on adjacent pelvic organs. Our case presented with a mass with mild discomfort.[1]

On gross examination it is a soft, bulky masses with a smooth external surface, measuring between 3 and 60 cm in greatest dimension. Pathologically they are composed of stellate and spindle-shaped cells distributed in a myxoid matrix with rich vascular supply.[1, 2]


Typical MR features of aggressive angiomyxomas consist of isointense or low-signal-intensity findings on T1WI and high-signal-intensity findings on T2WI. The high myxomatous content of these tumors is known to be responsible for the high signal intensity seen on T2WI. A whorled pattern of signal intensity on T2WI has been reported as a typical feature of aggressive angiomyxomas. Due to their inherent vascularity these tumors show strong contrast enhancement.[2, 3]

Major differential diagnosis is of Bartholin cyst however, these cysts do not typically show strong homogenous enhancement after contrast agent administration.[3]However, the wall may enhance if there is an inflammatory reaction. Other differentials include lipomas, myomas, hemangiopericytoma , and other malignant tumors such as melanomas, rhabdomyosarcomas, and squamous cell carcinomas. Myomas tend to have low signal intensity on T2WI. Lipomas show lack of signal on fat-suppressed images. Hemangiopericytoma show enhancement however whorled pattern on T2WI is lacking . Melanomas appear bright on T1WI due to internal hemorrhage or melanin content. Rhabdomyosarcomas usually occur in younger patients. Squamous cell carcinomas tend to invade into deeper parametrial structures. None of these tumors are expected to demonstrate whorled T2WI high signal intensity.[3, 4]

Wide local excision is the known treatment of choice for aggressive angiomyxoma. Incomplete excision leads to local recurrence in up to 30% of cases. There are no reports of distant metastases from aggressive angiomyxomas. MR imaging helps in demonstrating the unusual growth patterns and to plan the best surgical route for excision of such tumors.

Differential Diagnosis List

Final Diagnosis

Aggressive angiomyxoma of the vulva

URL:	https://www.eurorad.org/case/11101
DOI:	10.1594/EURORAD/CASE.11101
ISSN:	1563-4086