By Ahmad Alomari
Vascular anomalies can be broadly classified into vascular tumours (eg. infantile haemangioma) and vascular malformations. The two main categories of vascular malformations are slow-flow (venous, lymphatic and capillary malformations) or fast-flow (arteriovenous malformations and fistulas). The interventional management of vascular malformations is the primary minimally-invasive therapy which largely replaced the surgical approach. The use of accurate terminology to describe this heterogenous, occasionally overlapping group of disorders is crucial for proper management and research. Unfortunately, despite the major improvement in the clinical, genetic and therapeutic management of vascular anomalies, myths and misconceptions about the diagnosis and management of these anomalies continue to be surprisingly pervasive with frequent serious consequences.
Dispelling some of these common myths can only help the management of this challenging disorder.
Myth 1. Modern medical practice uses proper terminology for vascular anomalies
Partially correct! The common use of inappropriate terms such as “lymphangioma”, “cystic hygroma”, “cavernoma” or “cavernous haemangioma”, does not attest to this statement. Vascular malformations are not tumours. Old, imprecise tumour-denoting terms (such as the suffix “oma”) should be avoided. “Lymphangioma” and “cystic hygroma” should be replaced by the proper name “lymphatic malformation.” Similarly, the use of “cavernoma” or “cavernous haemangioma” to refer to venous malformations is inappropriate.
Myth 2. Interventional radiology management of vascular anomalies is the only justified practice
Managing patients with vascular anomalies usually requires the collaboration of several experienced specialties, including interventional radiology. The unidisciplinary approach is hardly justified in modern medicine.
Myth 3. Interventional radiologists are well-trained to manage vascular anomalies
This is correct for only a handful of institutions. A reasonably large volume of patients with vascular anomalies is essential to consolidate such experience. In reality, the current high-intensity interventional radiology fellowship training cannot provide a comprehensive knowledge base and the practical skills necessary for managing these diseases in a one-year period. I advocate further specific training and re-training in this field beyond the fellowship and institutional experience limits.
Myth 4. Surgical management of vascular anomalies is an antiquated practice
Imprecise! For some vascular anomalies, successful management can be primarily achieved surgically. In addition, combined interventional radiological-surgical approach is particularly helpful for large vascular anomalies requiring eventual debulking and for cosmesis and solid components of vascular anomalies.
Myth 5. Magnetic resonance angiography (MRA) and magnetic resonance venography (MRV) are standard parts of the protocol for imaging vascular anomalies
Difficult to prove! One of the common mistakes in imaging vascular anomalies is studying local blood vessels with MRA and MRV without standard cross-sectional sequences. For the vast majority of the vascular anomalies, MRA and MRV provide little, if any additional information. Contrary to the common belief, MRA and MRV studies are not essential for the diagnosis of arteriovenous malformations, which can be imaged by standard cross-sectional sequences. Nevertheless, the 3D data can be helpful in characterising and planning the management of some fast-flow anomalies.
Myth 6. Contrast enhancement is essential to differentiate venous from lymphatic malformation
Most of the time, contrast enhancement is not needed for this particular purpose. The classic T2 magnetic resonance imaging (MRI) signal of venous malformations is anamorphous mass of very thin septations (malformed venous walls) containing stagnant blood and clots without solid components. Blood stagnation very commonly causes fluid-fluid level. Enhancement of venous malformations is patchy and heterogenous while only septal enhancement is typically seen in lymphatic malformations. Nevertheless, with characteristic T2 features, enhanced sequences are not essential for diagnosis.
Myth 7. Lymphaticovenous malformations are commonly noted on imaging
This myth is expressed far too often. For isolated, non-syndromic slow flow malformations, the common use of “lymphaticovenous malformation” is incorrect. These malformations are composed predominantly of one anomalous vascular lineage and the diagnosis is simply either “venous” or “lymphatic” malformations.
Myth 8. “Klippel-Trenaunay-Weber syndrome” is a proper diagnosis
False! Klippel-Trenaunay syndrome and Parkes Weber syndrome are completely different clinical entities. In fact, there is no such eponym as “Klippel-Trenaunay-Weber syndrome”! Parkes Weber syndrome is characterised by a limb overgrowth with capillary stain and hypervascularity of the soft tissue. In Klippel-Trenaunay syndrome, limb overgrowth is composed of extrafascial fatty thickening, ectatic marginal venous system and lymphatic malformations.
Myth 9. Arteriovenous malformations can be precisely diagnosed with angiography
This is true—to a point. Fast flow, early venous filling and even arteriovenous shunting are not a sine qua non of arteriovenous malformation. Benign hypervascular masses (eg. hepatic infantile hemangioma) and extensive capillary malformations demonstrate marked hypervascularity, overgrowth and early venous filling without discreta arteriovenous shunting. Arteriovenous malformations by definition are primary lesions with no solid mass component.
Myth 10. “Liver hemangioma” and “vertebral hemangioma” are benign tumours
The so called “liver hemangioma” and “vertebral hemangioma” are not tumours, as the suffix “oma” suggests. These two entities are peculiar slow-flow venous lesions, not tumours.
Ahmad Alomari is an associate professor at Harvard Medical School, Boston Children’s Hospital, Boston, USA