Bold opening: A giant left iliofemoral AVM can masquerade as a simple lump, but hidden high‑flow vascular mischief demands precise imaging and careful treatment planning.
But here’s where it gets controversial: ultrasound often plays a screening role rather than the final say, yet it can profoundly shape our understanding of complex AVMs when used alongside angiography. This case shows how ultrasound, CT, and MRI findings align with interventional outcomes to confirm a giant internal iliac AVM in a 46-year-old patient—and how targeted embolization can achieve a definitive cure.
Introduction
Arteriovenous malformation (AVM) is a congenital, high‑flow vascular disorder defined by direct artery-to-vein connections that bypass a capillary network, forming a tangled vascular nidus. While AVMs most commonly affect the head and neck, they can involve pelvic vessels such as the internal iliac arteries on rare occasions. Digital Subtraction Angiography (DSA) remains the gold standard for diagnosis and guiding interventional therapy, but ultrasound serves as a practical screening and follow‑up tool and can contribute meaningful information to the diagnostic puzzle when used with other imaging modalities. This report describes an internal iliac AVM confirmed by interventional treatment, analyzes its imaging features, and discusses the clinical value of ultrasound in context with the literature.
Case Presentation
A 46-year-old woman presented with a 15‑year history of a painless mass in the left buttock, recently enlarging markedly over one month. Exam revealed a warmer skin temperature over the mass, bluish vascular shadows on the surface, and audible vascular murmurs. Routine ultrasound showed a 129 × 70 mm mixed cystic‑solid mass in the left hip with ill-defined borders. Multiple large vascular echoes were present within the lesion, and a potential arteriovenous fistula was suggested by the blood flow spectrum. The study favored a solid mass in the left buttock with a need to rule out an arteriovenous fistula.
Pelvic CT demonstrated multiple tortuous, dilated vessels in the left gluteal subcutaneous tissue, compatible with an AVM and possible adjacent soft tissue infection and edema. MRI revealed a mass with characteristic flow voids, consistent with high‑flow vascular channels. Specific MRI features included serpiginous flow voids on both T1‑weighted and T2‑weighted sequences, supporting a high‑flow vascular lesion.
Angiography and Endovascular Treatment
During endovascular embolization, bilateral internal iliac arteriography identified an extensive left gluteal AVM, predominantly supplied by the left internal iliac artery with additional contributions from branches of the right internal iliac artery. Venous drainage was mainly via the left iliac venous system. Post‑embolization angiography showed disappearance of the arteriovenous fistula. The final postoperative diagnosis was a left internal iliac AVM. The patient recovered well and was discharged on postoperative day 3.
Imaging Highlights
- Doppler ultrasound: high‑velocity, low‑resistance (HVLR) arterial flow within a mass with abundant vascular echoes, suggesting a high‑flow lesion rather than a simple cyst or solid tumor.
- CT angiography: tortuous, dilated vessels in the left gluteal region, aligning with AVM morphology.
- MRI: flow voids indicating rapid intralesional flow; T1 and T2 sequences demonstrated the vascular nidus and feeding/draining vessels.
- DSA: detailed mapping of feeding arteries (primarily left internal iliac), nidus, and draining veins, enabling precise embolization targeting.
Discussion
An AVM comprises feeding arteries, a nidus, and draining veins, with the nidus replacing the capillary bed and allowing direct arteriovenous shunting. Some theories suggest that congenital AVMs can induce venous dilation in nearby tissues, which may trigger microscopic arteriovenous communications that progressively form the lesion. Clinically, AVMs commonly present as pulsatile masses with mild warmth and may ulcerate or bleed; in severe cases, they can cause high‑output cardiac failure. Although AVMs are present from birth, symptoms often become evident in childhood or adolescence, making adult presentations like this case relatively rare.
Imaging and diagnostic considerations
- Ultrasound serves as an effective initial screen: it can reveal an irregular, vascular‑rich mass and detect a high‑velocity, low‑resistance spectrum that points toward a high‑flow AVM. However, ultrasound alone cannot delineate the complete feeding artery–nidus–draining vein anatomy.
- Angiography provides definitive delineation: it clarifies the full vascular architecture, enables precise embolization planning, and confirms the absence or presence of arteriovenous shunting.
- MRI offers supportive, noninvasive confirmation: flow voids on T1WI and T2WI indicate rapid flow within vascular channels and help differentiate AVMs from other soft tissue lesions.
- Differential diagnosis is essential: AVMs must be distinguished from venous malformations (which typically display venous-type flow on Doppler and lack arteriovenous shunting) and congenital hemangiomas (which can be rapidly involuting or noninvoluting and may mimic AVMs). Angiography helps confirm whether true arteriovenous shunting exists. Misclassification can lead to inappropriate management, so a careful, multimodal imaging approach is advisable.
Clinical takeaway
Ultrasound, especially Color Doppler, provides valuable early clues about a suspected high‑flow vascular malformation by showing abundant vascularity and a HVLR spectral pattern. When such findings are present, proceeding to DSA for definitive mapping supports targeted transarterial embolization, which can effectively treat the AVM and reduce the risk of progression or complications. MRI adds corroborating evidence through flow voids and nidus characterization, while CT/CTA can illustrate the extent of vascular involvement.
Limitations and future directions
This report reflects a single case; therefore, the conclusions may not generalize to all AVMs. Prospective studies with larger patient cohorts are needed to standardize ultrasound protocols, define clear follow‑up strategies, and optimize multidisciplinary approaches for rare pelvic AVMs.
Notes
First author and corresponding author details are provided in the original report.
Would you like this rewritten version to emphasize practical guidance for clinicians, patient‑facing explanations, or both? Also, should I tailor the tone to a medical journal audience or a general readership with lay explanations?
