Masses of developmental and genetic origin affecting the paediatric craniofacial skeleton

Abstract

Although rare, masses and mass-like lesions of developmental and genetic origin may affect the paediatric craniofacial skeleton. They represent a major challenge in clinical practice because they can lead to functional impairment, facial deformation and disfigurement. The most common lesions include fibrous dysplasia, dermoid cysts, vascular malformations and plexiform neurofibromas. Less common lesions include torus mandibularis and torus palatinus, cherubism, nevoid basal cell carcinoma syndrome, meningoencephalocele and nasal sinus tract. This article provides a comprehensive approach for the evaluation of children with masses or mass-like lesions of developmental and genetic origin affecting the craniofacial skeleton. Typical findings are illustrated and the respective roles of computed tomography (CT), cone beam CT (CBCT), magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) sequences and ultrasonography (US) are discussed for the pre-therapeutic assessment, complex treatment planning and post-treatment surveillance. Key imaging findings and characteristic clinical manifestations are reviewed. Pitfalls of image interpretation are addressed and how to avoid them. TEACHING POINTS: • Masses of developmental and genetic origin may severely impair the craniofacial skeleton. • Although rare, these lesions have characteristic imaging features. • CT, MRI and ultrasonography play a key role in their work-up. • Recognition of pivotal imaging pearls and diagnostic pitfalls avoids interpretation errors.

Keywords: CT; Developmental lesions; Head and neck; MRI; Maxillofacial.

Fig. 1

Fibrous dysplasia (FD) of the maxilla in a 12-year-old boy with rapidly increasing facial asymmetry. a Axial computed tomography (CT) scan (bone window) shows expansile lesion of the left zygomatic arch with ground-glass opacity (arrow). b Three-dimensional CT volume rendering (VR) reconstruction depicts zygomatic bone remodelling involving the floor and lateral wall of the orbit and the zygomatic arch (arrows). Partial surgery was performed six years later for cosmetic reasons. c Low-power photomicrograph obtained after partial lesion resection reveals irregular, curvilinear trabeculae of woven and lamellar bone surrounding fibrous tissue with bland-appearing fibroblastic cells (original magnification, ×100; haematoxylin and eosin [H&E] stain). At higher power, (inset in c), the bone trabeculae are devoid of osteoblastic rimming (original magnification, ×200)

Fig. 2

Magnetic resonance imaging (MRI) findings of FD involving the greater wing of sphenoid bone in a patient with left orbital pain. Axial (a) and coronal (b) CT images (bone window) show an enlarged greater wing of the left sphenoid bone (arrows) with medullary expansion and intact cortical outline. Ground-glass opacities within the affected bone. No bone destruction. c Diffusion-weighted imaging ((DWI) reveals intermediate signal on the b = 1000 image (arrowhead, upper image part) and on the ADC map (arrowhead, lower image part, apparent diffusion coefficient [ADC] = 1.4 × 10⁻³ mm²/s). d Heterogeneous low signal on T2 without intracranial extension. e Homogeneous low T1 signal (arrow). f Heterogeneous non-specific enhancement on the gadolinium-enhanced coronal fat-saturated T1 (arrowhead)

Fig. 3

An 8-year-old boy with progressive painless and symmetric bilateral facial enlargement. a Translucent cone beam CT (CBCT) thick-slab reconstruction shows well-defined bilateral multilocular radiolucencies with deformation and symmetric bilateral enlargement of the mandible and maxilla, and dental abnormalities (displaced permanent teeth and unerupted first molars). Axial (b) and coronal (c) CBCT images show multilocular pseudocystic osteolytic lesions with a few irregular bony septa (asterisks), no periosteal reaction, teeth displacement and inferior alveolar nerve canal invasion. d Hypertrophic osteolytic mandibular and maxillary lesions typical of cherub face as seen on the three-dimensional CBCT reconstruction

Fig. 4

Typical manifestations of nevoid basal cell carcinoma syndrome (NBCCS) in a 16-year-old boy. a Orthopantomography (OPT) shows cystic lesions of the mandible and maxilla (arrows), with unilocular and multilocular pattern and smooth or scalloped borders associated with displaced and unerupted permanent teeth. b Coronal CT scan (bone window) shows ectopic calcifications of the falx cerebri and tentorium cerebelli (arrows) and spotted meningeal calcifications (arrowheads). Brain MRI reveals a cavum veli interpositi on axial T2 (asterisk in c) and coronal contrast-enhanced T1 (asterisk in d) and also vermian dysgenesis (arrowheads in d)

Fig. 5

Characteristic radiological findings of odontogenic keratocyst (OKC) as seen in an elderly male. a OPT shows a large, well-defined osteolytic lesion involving the body and angle of the mandible on the right encompassing the right inferior alveolar nerve canal (arrow). Absence of root resorption (asterisks). b Multiplanar reformatted CT image (bone window) shows an unilocular cystic expansile lesion extending into the right inferior alveolar nerve canal (arrowhead). No periosteal reaction or pathological fracture. T1 (c) and T2 (d) axial images reveal thinned cortex (arrows) with postero-inferior cortical breach. e DWI reveals high signal on the b = 1000 image (arrowhead, upper image part) and low signal on the ADC map (asterisk, lower image part, ADC = 0.7 × 10⁻³ mm²/s), compatible with restricted diffusion due to intralesional ortho-/parakeratin accumulation and/or haemorrhage. f Subtraction image (T1 post-contrast and T1 pre-contrast) in the sagittal oblique plane shows only a thin enhancing lesion rim (arrowheads)

Fig. 6

Torus palatinus (TP) in a 3-year-old girl who underwent imaging because of an indurated palpable midline mass of the hard palate increasing in size (a) after a fall occurring from a swing hanging on a tree two weeks earlier. Coronal low-dose CT image (bone window) (b) and three-dimensional CT VR reconstruction show a small midline spur/exostosis (arrow and circle). Characteristic aspect of a torus mandibularis (TM) (asterisks in d and e), of a TP (arrowheads in e and f) and of a torus maxillaris (TMax) (arrows in f) as seen in a young adult. It is worthwhile mentioning that TM and TMax are extremely rarely diagnosed in children

Fig. 7

Intraosseous dermoid cyst (DC) in a 17-year-old male presenting as a gradually enlarging right supraorbital swelling since three years. a Cystic lesion in the right frontal bone (arrow) with non-lipomatous contents on axial T2. On T1 (b) and fat-saturated contrast-enhanced T1 (c), the lesion appears hypointense and displays intracystic serpiginous hyperintense areas which correspond to haemorrhage, high protein content or saponification (arrows). d DWI reveals high signal on the b = 1000 image (asterisk, upper image part) and low signal on the ADC map (asterisk, lower image part, ADC = 0.6 × 10⁻³ mm²/s), compatible with restricted diffusion and characteristic of an epidermoid cyst

Fig. 8

DC with bone remodelling in a 14-year-old male with lateral supraorbital soft tissue swelling and induration. a Axial CT (bone window) shows well-demarcated cystic subcutaneous lesion (arrowhead) with frontal bone scalloping and no cortical erosion (arrow). b Three-dimensional CT VR reconstruction shows bone remodelling in the supraorbital left area (arrow). c DWI reveals high signal on the b = 1000 image (arrowhead, upper image part) and high signal on the ADC map (arrowhead, lower image part, ADC = 2.5 × 10⁻³ mm²/s), compatible with no restricted diffusion and characteristic of a DC. d Peripheral lipid density on T2 (arrow, upper image part) and T1 with low signal (arrow in e) in gadolinium-enhanced coronal fat-saturated T1. Central soft tissue density on T1 (arrowhead in lower image part) with no contrast enhancement (arrowhead in e), corresponding to squamous debris

Fig. 9

Nasal dermoid sinus cyst (NDSC) visible since birth in a 15-year-old boy. a Sagittal contrast-enhanced CT scan (soft tissue windows) shows the extra- and intracranial dermoid cysts (white arrows), which connect with each other via the abnormal foramen caecum (black arrow). b High-resolution sagittal T2 shows that the cystic lesions have different signal intensities (arrows), suggesting different proteinaceous/lipomatous contents. Note also corpus callosum agenesis and posterior ethmoidal meningocele (asterisk). c The lipomatous content (arrowheads) of the NDSC appears hyperintense on T1 (upper image part) and hypointense on fat-saturated contrast-enhanced T1 (lower image part), respectively

Fig. 10

Rapidly enlarging painful plexiform neurofibroma (PNF) in a 15-year-old girl with neurofibromatosis type 1 (NF1). Imaging was performed before PNF resection. a Panoramic view shows mandible deformity (thinning and bowing of the right ascending ramus of the mandible and the right mandibular body) with involvement and enlargement of the right inferior alveolar nerve canal (arrow). b The axial T2 images reveal extensive PNF (asterisks) with a characteristic “target sign”: central T2 hypointensity within the multilobulated hyperintense mass (arrowheads). c Gadolinium-enhanced coronal fat-saturated T1 shows large, infiltrative and multilobulated PNF involving the entire hemiface with perineural spread and extension to the right foramen ovale (arrow). d Immunohistochemistry (original magnification, ×40; S100 protein) obtained from surgical specimen highlights plexiform nerve bundles (arrows) dissecting the adipose tissue of the hypodermis (asterisk). Numerous confluent Wagner-Meissner bodies are seen (inset, original magnification, ×200; H&E stain)

Fig. 11

Venous vascular malformation (VVM) in a 12-year-old girl complaining of increasing left cheek swelling causing major facial asymmetry and dental malocclusion. a Grey-scale ultrasound (upper image part) and corresponding Doppler US (lower image part) show hypoechoic and infiltrative mass with poor vascularisation. b Axial low-dose CT (bone window) shows shortened and remodelled left ascending ramus of the mandible (arrowhead) and increased distance (arrow) between the left ascending ramus of the mandible and posterior wall of the left maxillary sinus, compatible with a slow-growing lesion. c This increased distance is also clearly seen on the three-dimensional CT VR reconstruction. STIR (d) and T2 (e) images show a hyperintense mass with multiple small phleboliths (small, dark, rounded areas) situated within Bichat’s fat (arrows). f Contrast-enhanced axial fat-saturated T1 shows partial, progressive, centripetal lesion enhancement (arrowhead) characteristic of a VVM

Fig. 12

Lymphatic malformation (LM) in a term-born-boy presenting with a large anterior and lateral neck mass beneath a bluish-coloured skin. a Ultrasound of the neck shows that the mass is composed of large fluid-filled macrocystic (asterisk) and microcystic (arrowheads) portions. b Sagittal T2 illustrates the macrocystic submental component extending into the base of the tongue (arrow). Percutaneous sclerotherapy was carried out. Post-sclerotherapy follow-up MRI (c, d). c Axial T2 depicts intracystic fluid/fluid levels due to internal bleeding (arrows). Fat-saturated, contrast-enhanced T1 (d) shows enhancement of the thin septae of the macrocystic and microcystic components. Two years later, the mandibular deformation is visible on the follow-up MRI (T2W image, e, arrowheads) and on an x-ray image (f, arrows), obtained during percutaneous sclerotherapy (asterisk)

Fig. 13

Meningoencephalocele in a 13-month-old boy of African origin with a large midline facial mass. a Sagittal CT (brain window) shows herniation of cranial content through a bony defect located in the anterior skull base. The herniation contains a cyst-like mass with multiple septations and lined by glial tissue and/or meninges (arrow). b The exact size and configuration of the bony defect, as well as the extent of orbital bony malformation, is better appreciated on the three-dimensional CT VR reconstruction of the bony skull (asterisk). c Three-dimensional CT VR illustrating the extent and position of the meningoencephalocele with respect to the craniofacial skeleton. d Axial T2 shows cystic cerebrospinal fluid (CSF)-filled meningocele structures displacing the globes laterally and a suprasellar cyst (asterisk). e Fused sagittal CT and T2 illustrate CSF, parenchymal and bony abnormalities. Large suprasellar cyst (asterisk) lined by Liliequist membrane