Arteriovenous malformation

Arteriovenous malformation (AVM) of the jaws is a congenital high-flow vascular malformation characterized by abnormal direct connections between dysplastic arteries and draining veins through intervening nidal vessels, bypassing the normal capillary bed.[1][2] The pathological angioarchitecture consists of a feeding artery, a central nidus, and an outflowing vein; venous arterialization causes progressive luminal dilation and compression of surrounding bone.[3] Intraosseous jaw AVMs are among the most dangerous hemorrhagic lesions of the maxillofacial region, with a high tendency toward life-threatening bleeding, particularly when provoked by dental extraction or during the mixed-dentition period.[4][5] On panoramic radiographs, the signature pattern is an osteolytic radiolucency—often centered on the premolar-molar region—with indistinct margins and variable internal septation.[4][6] Management centers on endovascular embolization, with or without surgical resection.[1][7]

Current classification

Under the International Society for the Study of Vascular Anomalies (ISSVA) classification, AVMs and arteriovenous fistulas (AVFs) are categorized as high-flow (fast-flow) vascular malformations, distinct from low-flow malformations (venous, lymphatic, capillary) and from vascular tumors.[2][8] The 2025 ISSVA update retains this framework and integrates molecular-genetic features.[8]

• Arteriovenous malformation (AVM): abnormal arteriovenous connections through a nidus of dysplastic vessels.
• Arteriovenous fistula (AVF): a direct single-channel communication between an artery and a vein without an intervening nidus.[2][9]

Obsolete and confusing terms

The term "central hemangioma" was historically applied to intraosseous jaw AVMs but is now considered incorrect; the ISSVA classification reserves "hemangioma" for vascular tumors with endothelial proliferation, not developmental malformations.[3][8] The Mulliken and Glowacki biologic classification (1982), which first separated vascular tumors from malformations, forms the foundation of current nomenclature.[8][10]

Clinical staging

The Schobinger system stages the natural history of AVMs:

• Stage I (quiescence): skin discoloration and warmth
• Stage II (expansion): enlargement with palpable pulsation
• Stage III (destruction): ulceration, tissue destruction, pain, profuse bleeding
• Stage IV (decompensation): high-output cardiac failure (rare in head and neck AVMs)[1]

• Frequency: Jaw AVMs are rare. Approximately 50% of extracranial AVMs affect the head and neck, with predilection for the midface and oral cavity.[1]
• Age: Mean age at presentation is approximately 22 years in a large series of 211 jaw AVMs, though diagnosis may be delayed because of insidious onset in childhood.[3][4]
• Sex: Slight male predominance (male-to-female ratio approximately 4:3).[4]
• Site: The mandible is affected roughly twice as often as the maxilla (approximately 65% vs. 32%). Within the jaws, the vast majority (>95%) involve the posterior teeth region (premolar and molar areas).[4]
• Head and neck AVFs can be primary (congenital/spontaneous) or secondary (traumatic/iatrogenic); secondary AVFs are almost twice as common as primary AVFs in the head and neck overall.[11]

Presentation and symptoms

• Bleeding is the most common presenting complaint, ranging from chronic periodontal oozing to acute massive oral hemorrhage. Life-threatening hemorrhage may be triggered by tooth extraction, exfoliation of deciduous teeth, or incisional biopsy.[3][4][5]
• Facial swelling, asymmetry, and soft-tissue discoloration (bluish-red mucosal or gingival color) are common.[6]
• Spontaneous gingival bleeding, erythematous and edematous gingiva, and tooth mobility are frequently observed.[3][6]

Examination findings

• Pulsation may be palpable when the lesion erodes through cortical bone into soft tissue.[3]
• Elevated cutaneous temperature over the affected area is a hallmark of high-flow malformations.[3]
• A thrill or bruit may be detected on auscultation.[9][11]
• Teeth in the affected region may show mobility and root resorption.[3][6]

Tempo and complications

AVMs are present at birth but may remain clinically silent until puberty, trauma, or dental procedures provoke expansion or hemorrhage.[1][12] Progression through Schobinger stages can be accelerated by hormonal changes or iatrogenic manipulation. Catastrophic hemorrhage during dental extraction is the most feared complication and has resulted in fatalities.[3][5] Numbness of the inferior alveolar nerve distribution may occur with large mandibular lesions.[6]

Location and distribution

Intraosseous jaw AVMs strongly favor the posterior mandible (premolar-molar region), with the mandibular body being the most common site.[3][4] Maxillary lesions are less frequent and tend to involve the posterior alveolar process and may extend into the maxillary sinus.[4] Lesions are typically centered on or adjacent to tooth roots, often around the first molar.[4]

Periphery and shape

• Mandibular AVMs classically present as oval or irregularly shaped radiolucencies with indistinct (ill-defined) margins on panoramic radiographs.[4][6]
• Corticated borders are generally absent, distinguishing AVMs from most odontogenic cysts.[6][13]
• Shape ranges from a well-circumscribed oval lucency in smaller lesions to large, irregular, poorly marginated destructive areas in advanced cases.[3][4]

Internal architecture

• A macrocystic pattern (a single large area of radiolucency) on panoramic radiography suggests an intact mandibular cortex and a less extensive lesion.[3]
• A microcystic pattern, described as "soap bubble" or "honeycomb" septation, suggests more aggressive disease with soft-tissue involvement.[3]
• Some lesions show coarsened or altered trabecular patterns within the radiolucency. Occasionally, a "sunburst" periosteal reaction may be seen, mimicking malignancy.[13]
• Maxillary AVMs may produce a diffuse ground-glass opacification of the maxillary sinus on panoramic radiographs, rather than a discrete lucency.[4]

Effects on teeth and adjacent structures

• Root resorption of teeth within or adjacent to the lesion is common and may be the first radiographic clue.[3][6]
• Tooth displacement and mobility are frequently observed.[6]
• Widening of the periodontal ligament space around involved teeth may be present.
• The inferior alveolar canal may be displaced or obscured by mandibular lesions.[13]

Cortical involvement and extent

• Cortical expansion and thinning are common; frank cortical perforation occurs in advanced lesions and correlates with palpable pulsation clinically.[3]
• CBCT provides superior assessment of cortical integrity, including buccal and lingual cortical thinning, perforation, and three-dimensional extent of the lesion compared with panoramic radiography.[14]
• CBCT can delineate the relationship of the lesion to the inferior alveolar canal, mental foramen, and maxillary sinus floor with greater accuracy.[14]

Variants and atypical presentations

• Small, early-stage AVMs may appear as subtle periapical or pericoronal radiolucencies, mimicking periapical pathology or dentigerous cysts.[13]
• Rare phleboliths (calcified thrombi) may be identified within or adjacent to the lesion, more commonly associated with venous malformations but occasionally seen in AVMs with a venous component.[15]
• Bilateral jaw involvement is uncommon but has been reported in syndromic settings.[12]

MRI

MRI is the preferred cross-sectional modality for characterizing AVMs.[16] Key findings include:

• Flow voids on T1- and T2-weighted sequences, representing high-velocity blood flow through the nidus and enlarged vessels.[6][16]
• Dilated, tortuous feeding arteries and ectatic draining veins are visualized on contrast-enhanced sequences.[1]
• Dynamic contrast-enhanced MR angiography (MRA) demonstrates early arterial filling and rapid venous drainage, confirming high-flow physiology.[17]
• MRI delineates soft-tissue extent and involvement of adjacent structures (muscles, nerves, subcutaneous tissue) that may not be apparent on dental radiographs or CBCT.[18]

CT angiography

• Contrast-enhanced CT demonstrates avid enhancement within the cancellous bone of the affected jaw.[4]
• CT angiography (CTA) offers superior temporal resolution for mapping feeding arteries and draining veins and is useful for pretreatment planning, particularly when MRI findings are equivocal or bony detail is needed.[17]
• Three-dimensional CT reconstruction can reveal expansion and erosion of the mandibular body.[1]

Conventional angiography

• Digital subtraction angiography (DSA) remains the gold standard for definitive diagnosis and treatment planning. It demonstrates distended feeder vessels, the nidus, arteriovenous shunting, and early venous filling in real time.[1][6][16][17]
• DSA is typically performed immediately before or during embolization procedures.[1]

Ultrasound

• Doppler ultrasonography demonstrates enlarged vascular channels with low-resistance, high-velocity arterial waveforms and spectral broadening, confirming high-flow physiology in superficial or soft-tissue components.[1][17]

Intraosseous jaw AVMs produce nonspecific osteolytic radiolucencies that overlap with a range of odontogenic and non-odontogenic entities. The clinical context—particularly unexplained gingival bleeding, pulsation, warmth, or tooth mobility in a young patient—should raise suspicion for a vascular lesion before any invasive procedure is performed.[5][13]

The highest-risk diagnostic pitfall is performing an incisional biopsy or tooth extraction without first suspecting a vascular lesion. When an intraosseous radiolucency is associated with unexplained bleeding, pulsation, or mucosal discoloration, needle aspiration should precede any biopsy; return of pulsatile arterial blood mandates advanced vascular imaging (MRI/MRA or CTA/DSA) and referral before further intervention.[3][5][13]

Histopathologic examination of jaw AVMs is rarely performed as a primary diagnostic step because of hemorrhage risk; tissue is typically obtained after embolization or at the time of surgical resection.[20]

Microscopic findings

• AVMs consist of a mixture of large, malformed thick-walled arteries and dilated thin-walled veins of varying caliber, with vessels of indeterminate lineage also present.[20][21]
• The arterial component often shows disruption of the internal elastic lamina with neointimal cushions; the venous component may display irregular wall thickening and neointimal hyperplasia.[21]
• Capillary-sized vessels arranged in a lobular pattern may be present and can be mistaken for lobular capillary hemangioma or congenital hemangioma.[21]
• Identification of the actual arteriovenous shunt on histologic sections can be challenging.[21]
• Elastic Verhoeff-Van Gieson stain highlights elastic fibers in thick-walled arteries; Masson trichrome highlights smooth muscle cells.[20]

Immunohistochemistry

• CD31: diffuse endothelial positivity.[20]
• α-smooth muscle actin (α-SMA): strongly highlights smooth muscle cells and pericytes.[20]
• GLUT-1: negative in approximately 79% of jaw AVMs, consistent with a vascular malformation rather than an infantile hemangioma (which is GLUT-1 positive).[20]
• D2-40: uniformly negative, excluding lymphatic differentiation.[20]
• Desmin: positive in approximately 56% of cases.[20]

Molecular findings

Sporadic extracranial AVMs are most commonly associated with somatic activating mutations in MAP2K1; KRAS and BRAF mutations are more characteristic of intracranial AVMs.[1][21] AVMs may also occur in the setting of hereditary hemorrhagic telangiectasia (ENG, ALK1 mutations), capillary malformation–AVM syndrome (RASA1, EPHB4 mutations), PTEN hamartoma tumor syndrome, and CLOVES syndrome.[1][21]

Workup and referral

Any jaw radiolucency suspected of being vascular warrants needle aspiration before biopsy.[5] If pulsatile blood is obtained, the patient should be referred to a multidisciplinary vascular anomalies team (interventional radiology, oral and maxillofacial surgery, head and neck surgery) for advanced imaging and treatment planning.[5][22] MRI/MRA is the preferred initial cross-sectional study; DSA is performed for definitive angioarchitectural mapping and typically immediately before embolization.[1][16]

Definitive treatment

• Embolization is the primary treatment modality. The goal is to deliver embolic material into the nidus and immediate draining veins rather than to occlude proximal feeding arteries, which may stimulate collateral angiogenesis and worsen the lesion.[1][7]
  • Approaches include transarterial catheter embolization, direct percutaneous puncture of the nidus, or a combination ("double interventional therapy").[7]
  • Embolic agents include dehydrated ethanol, acrylate glue (N-butylcyanoacrylate), and ethylene-vinyl alcohol copolymer (Onyx). For intraosseous jaw AVMs, fibered platinum coils may be placed first to reduce flow, followed by ethanol embolization.[1][7]
• Surgical resection is reserved for small, well-circumscribed lesions or those refractory to embolization. Preoperative embolization within 24–48 hours reduces intraoperative blood loss.[1]
• Combined embolization and resection is often required for large or complex lesions.[1][23]
• Interstitial bleomycin injection has been reported as effective for early-stage (Schobinger I–II) AVMs.[1]
• No established systemic medical therapy exists, though genotype-guided therapy targeting MAP2K1 activation has shown success in isolated refractory cases.[1]

Recurrence and prognosis

Complete cure is often unrealistic for large, diffuse AVMs; the treatment goal is lesion control, symptom reduction, and preservation of vital functions.[1] Recurrence rates vary widely and recurrences have been documented up to 10 years after treatment.[1] Lesion size >6 cm is a significant predictor of recurrence after surgical resection.[24] In a review of 50 mandibular AVMs treated primarily with embolization, clinical stability with cessation of bleeding was achieved in 50% and reossification in 46%, though complications (mostly minor and transient) occurred in half of cases.[25] Long-term surveillance with clinical examination and periodic imaging is essential.[25]

Syndromic associations

Jaw AVMs may occur as part of several genetic syndromes that alter management:

• Hereditary hemorrhagic telangiectasia (HHT/Osler-Weber-Rendu): associated with mucocutaneous telangiectasias and visceral AVMs; screening for pulmonary and hepatic AVMs is indicated.[1][21]
• Capillary malformation–AVM syndrome (CM-AVM): caused by RASA1 or EPHB4 germline mutations; multiple small AVMs may be present.[1][21]
• PTEN hamartoma tumor syndrome and CLOVES syndrome: rare associations that carry additional tumor surveillance requirements.[1]

Pediatric considerations

Jaw AVMs may present catastrophically during the mixed-dentition period when deciduous teeth exfoliate, exposing the vascular nidus.[3] Dental practitioners managing children with unexplained gingival bleeding or radiographic lucencies in the posterior jaws should maintain a high index of suspicion and avoid extraction without prior vascular workup.[3][5]

The article above synthesizes evidence from a large 211-patient jaw AVM cohort, the ISSVA classification framework, a comprehensive JAMA review of head and neck vascular malformations, an immunohistochemical characterization of 16 jaw AVMs, molecular advances in vascular anomaly classification, and a systematic analysis of 50 embolization-treated mandibular AVMs, among other sources.[1][2][4][8][20][21][25] Key radiographic descriptors (macrocystic vs. microcystic patterns, indistinct margins, root resorption) are drawn from the largest available clinical-imaging series.[3][4] The critical safety message—that needle aspiration must precede biopsy when a vascular lesion is suspected—is emphasized in both the differential and management sections, consistent with multiple authoritative sources.[3][5][13]