‘Vascular anomaly’ is an umbrella term for local, structural aberrancies in the vasculature that can affect arteries, veins, capillaries as well as lymphatic vessels [24]. The first classification for vascular anomalies, by Virchow and Wegner, was solely based on histopathological features (Additional file 1) [20]. In 1982 Mulliken and Glowacki classified anomalies based on the endothelial cellular kinetics, coupled with the clinical manifestation and physical findings (Additional file 2) [23, 36]). They divided vascular anomalies into tumors and vascular malformations. This clinically more meaningful classification formed the base for the ‘International Society for the Study of Vascular Anomalies’ (ISSVA) classification. This classification was first introduced in 1996, and is now widely accepted in the literature (Additional file 3) [10]. In clinical practice, the nomenclature does often not match the ISSVA classification [32]. However, a correct terminology is crucial as the vascular anomalies can be diagnosed and treated by a variety of specialists and the various types of anomalies require different treatments [1]. In the past, surgery was the main and sometimes only available treatment modality. In recent years there has been a trend towards more minimally invasive techniques and medication [40].

After a synopsis of the most common types of vascular anomalies, we present an overview of all patients with vascular anomalies who presented at the department of oral and maxillofacial surgery (OMFS) in the university hospitals of Leuven in a 16-year period, focusing on nomenclature, classification, epidemiology, diagnostics, treatment, complications and outcome.

Infantile hemangiomas (IHs) are the most common and best-known vascular tumors. IHs have a characteristic growth pattern: they are absent or merely visible at birth, start growing before the fourth week, stop expanding before the fifth month and involute spontaneously after 6 to 12 months [3, 14]. In 40–50% of the patients, IHs leave residual skin changes, e.g. discolouration, fibro-fatty tissue,… [14]. The standard therapy for IHs is propranolol, which accelerates regression and ultimately reduces residual lesions [39].

Congenital hemangiomas (CHs) are fully developed at birth and have no postnatal proliferative phase. There are two main variants: rapidly involuting CHs start involuting within the first year after birth, while non-involuting CHs never regress [3]. CHs do not respond to pharmacological therapies and thus resection is the treatment of choice [7].

Lobular capillary hemangiomas (LCHs) are common benign vascular tumors with a prevalence of 0.5 to 1% in the general population [9, 34]. They occur mainly in the head-and-neck region and intra-orally, on the gums, tongue, lips and buccal mucosa [9, 38]. The synonym ‘pyogenic granuloma’ is a misnomer because lobular capillary hemangiomas are not associated with pus and do not histologically resemble granulomas [38].

Vascular malformations are always present at birth, whether symptomatic or visible. They never regress spontaneously and grow in relation with the patient. There may be periods of accelerated growth, for example at puberty or pregnancy, due to hormonal changes [15].

Venous, capillary, lymphatic and arteriovenous malformations are simple malformations. Combined malformations consist of two or more types of simple malformations, e.g. capillary-venous malformations, capillary-venous-arteriovenous malformation, … [15]. If a vascular malformation has an arterial component, it is categorized as a high flow malformation. All other malformations have a low flow [15].

A venous malformation (VM) is a soft, non-pulsating, compressible lesion that swells when the central venous pressure rises. The overlying skin or mucosa may be bluish or normal, depending on the depth of the VM [15]. Congestion in the VM can cause chronic pain. Intralesionally formed thrombi evoke a more intense pain [14, 19]. Calcified thrombi, also known as phleboliths, are pathognomonic for VMs [14].

Therapy consists of sclerotherapy, surgical resection, laser-therapy for superficial VMs (Nd:YAG) or a combination of these modalities. Small VMs can be excised if well-defined, with or without prior sclerotherapy, which helps to delineate the lesion and reduces intraoperative blood loss. For ill-defined, infiltrative and/or big lesions, sclerotherapy is the preferred treatment [33]. Laser-therapy is limited by its penetration depth, and thus can only be used for superficial VMs [27].

Lymphatic malformations (LMs) are the most common vascular malformations in the head- and neck region [29]. A local or systemic infection or hemorrhage can cause a temporary growth, which partially regresses once the infection is cleared. A macrocystic LM (individual cysts > 1 cm) feels soft, while the microcystic LM (individual cysts < 1 cm) is rather firm. They are generally painless, unless complicated with infection or intracystic hemorrhage, which turns the overlying skin or mucosa blue. LMs are often accompanied by overgrowth of soft and/or bony tissue [5, 25, 29].

LMs should only be treated if symptomatic or if acute swelling due to infection/hemorrhage could compromise neighboring vital structures (e.g. acutely endangered airway). LMs are difficult to eliminate completely without mutilating the surrounding tissue [37]. Macrocystic LMs can be treated surgically or with sclerotherapy, which are equally effective. Treatment of microcystic LMs is challenging as sclerotherapy is almost impossible and surgery is complicated by the infiltrative nature of microcystic LMs. Treatment with the mTOR inhibitor Sirolimus could address this challenge, as there are promising results [37].

Arteriovenous malformation (AVM) is an uncommon, dangerous, and difficult-to-treat anomaly. The capillary network between arteries and veins is missing, resulting in abnormal pressure and flow in the first part of the veins, which are dilated. The center of the AVM is called the nidus [6].

The clinical manifestation of an AVM changes as the patient ages and the lesion expands [28].

AVMs can be treated by surgical resection, embolization or (most often) the combination [17]. Because the recurrence rate is high (60–98%), the primary goal of therapy should be symptom relief, prevention of disfigurement and life-threatening situations [6, 17, 30].

Capillary malformation (CM) is a general term encompassing several types of lesions consisting mainly of capillaries, but with different characteristics and clinical courses. The best known types of CM are the nevus simplex and the nevus flammeus [10].

The nevus simplex, also known as ‘‘angel kiss’’, is a congenital CM most often found in the midline of the face and neck as a pink or bright red, blanchable lesion. The borders are blurred, but the contrast with surrounding tissue enhances with increasing blood pressure or vasodilatation. During the first two years of life, most lesions fade or disappear [13].

The nevus flammeus, also called “port wine stain”, is far less common than the nevus simplex with an incidence of 0,3%. The lesion is caused by a deficiency of the nerves in de the papillary plexus, which causes the capillaries to dilate continuously. The nevus flammeus hypertrophies and darkens with time [11]. In the face, port wine stains follow the distribution of the trigeminal nerve [4].

A CM is usually isolated but can also be part of a syndrome. Sturge-Weber syndrome is characterized by multiple CMs, mostly in the face, the ocular choroid, causing glaucoma, and in the ipsilateral meninges, resulting in epilepsy, stroke and intellectual disability [21].