ROUGH NOTES • CITATIONS

B B Lee ¹, J Laredo, T S Lee, S Huh, R Neville

Phlebology —  2007;22(6):249-52. doi: 10.1177/026835550702200604.

Abstract

Venous malformation (VM) is a congenital vascular malformation (CVM) that develops along the venous system through the various stages of embryogenesis. Older terminology and classification were often misleading and confusing. A newer classification system has emerged that is based on advances in the study of these conditions and is useful in contemporary management. The Hamburg classification was introduced after reappraisal of older terminology and has become the standard system for contemporary classification, which is based on anatomical, pathological and embryological criteria.

Affiliations Expand

• PMID: 18274331
• DOI: 10.1177/026835550702200604

To help visualize and understand the full schema, the classification is structured as follows:

1. Truncular Malformations

These occur later in embryonic development during the formation of the main vascular trunks. They tend to grow in proportion with the child, carry minimal risk of recurring after surgical intervention, and often lead to major hemodynamic consequences. [1, 2]

• Arterial: Aneurysms, stenoses, or aplasias.
• Venous: Aplasias, hypoplasias, or valvular incompetence (e.g., in Klippel–Trenaunay Syndrome).
• Arteriovenous (AV): Truncular AV fistulas (e.g., Parkes Weber Syndrome).
• Lymphatic: Truncular ectasias or lymphedema. [1, 2, 3, 4]

2. Extratruncular Malformations

These originate much earlier in embryogenesis from primitive mesodermal cells. They have a high potential to grow and proliferate, meaning they are prone to recurrence and often flare up after triggers like trauma, surgery, or hormonal shifts (e.g., puberty, pregnancy). [1, 2]

• Arterial: Localized extra-truncular AVMs.
• Venous: Localized extratruncular venous malformations (VMs).
• Lymphatic: Microcystic or macrocystic lymphatic malformations.
• AV Malformations: Diffuse or localized networks of abnormal arteriovenous connections. [1, 2, 3]

3. Combined Malformations

This category features multiple types of malformations occurring simultaneously within the same area (e.g., capillary-lymphatico-venous malformations). [1]

To explore more comprehensive visual diagrams and detailed case studies of how these classifications appear on imaging, you can review the Radiopaedia Vascular Malformations Article or dive into the clinical review on PMC. [1, 2]

FURTHER RESEARCH:

• The imaging characteristics typically seen on MRI or ultrasound.
• Expected hemodynamic consequences (such as high-flow vs. low-flow states).
• Common treatment options (like sclerotherapy or compression therapy) for specific malformations.

STATUS OF THE HAMBURG CLASSIFICATION MODEL

Hamburg is very much alive — and complementary, not competing.

Hamburg is described as one of the more commonly used systems to describe vascular malformations, largely replacing the many eponymous syndromes traditionally used. That matters — it means Hamburg did exactly what you experienced it doing: it replaced the confusing name-based labels like Klippel-Trenaunay-Weber Syndrome with structural descriptions. Compva

Hamburg operates primarily at the macroscopic level, while ISSVA can be utilized to classify lesions at the cellular level, distinguishing vascular malformations from vascular tumors. This is the key insight — they answer different questions. Hamburg answers where in embryological development did this go wrong and what does that mean for recurrence and treatment. ISSVA answers what type of vessel is involved and what is its flow characteristic. clinicaltrials

The unique contribution Hamburg makes — and ISSVA still partially lacks:

Hamburg provides clinical guidance based on embryological characteristics — the extratruncular type for lesions originating in early development, with potential for growth and proliferation causing recurrence, and the truncular type from later stages with more serious hemodynamic impacts. PubMed

That extratruncular/truncular distinction is clinically significant for your community specifically. Extratruncular malformations usually display significantly worse symptoms and higher recurrence than truncular forms, and thus this subtype is more likely to require treatment. For a KTS patient trying to understand why their port wine stain keeps coming back after laser treatment — that is the explanation. Extratruncular. Early developmental arrest. The genetic program keeps running. clinicaltrials

The relationship between the two systems:

The truncular/extratruncular nomenclature was not included in earlier ISSVA classifications; however, a designation for truncular-type lesions was added to the most recent update. So ISSVA absorbed Hamburg’s most important contribution — partially. Which means Hamburg still holds independent value for the parts ISSVA hasn’t fully integrated. Radiopaedia.org

What this means for our compendium specifically:

Hamburg gives something ISSVA does not — an embryological explanation that answers the question patients actually ask: “Why does mine keep coming back?” Extratruncular means early developmental arrest, mesenchymal cell remnants with ongoing proliferative potential. That is the biological explanation for recurrence in KTS after laser therapy, sclerotherapy, or surgery. IT IS RELEVANT.

MOVING FORWARD

Not replacing ISSVA with Hamburg. Not subordinating Hamburg to ISSVA. These are two lenses — the way a clinicians likely think:

• Flow characteristic (ISSVA lens): Slow-Flow, Fast-Flow
• Embryological origin (Hamburg lens): Extratruncular vs. Truncular