Diving Ranula

Findings

Figure 1 and Figure 2 Axial contrast-enhanced CT demonstrates a thin-walled, well-defined hypodense lesion in the right sublingual space (Figure 1) which herniates posteriorly into the submandibular space (Figure 1). This lesion also tracks into the sublingual space lateral to the right genioglossus muscle (Figure 2). It is located anterior and lateral to the right internal and external carotid arteries and effaces the submandibular gland.


Diagnosis: Diving Ranula


A diving ranula is an extravasation pseudocyst of a simple ranula in the sublingual space rupturing out into the submandibular and or parapharyngeal space. It originates from trauma or inflammation of the sublingual gland or minor salivary glands in the sublingual space. With obstruction of the gland duct, the duct dilates and eventually ruptures, allowing its secretions to leak into the surrounding soft tissue.

CT is the imaging study of choice. On CT, the lesion demonstrates water content and thin walls with subtle or no wall enhancement. If the lesion is infected, it may show thick, enhancing walls. The characteristic shape is a collapsed cystic portion in the sublingual space - “tail sign,” with its head extending into the submandibular space. The sublingual spaces are located on the floor of the mouth on either side of the midline genioglossus muscles. They are separated from the submandibular space by the mylohyoid muscle that extends from the medial inferior aspect of the mandible to the hyoid bone. Thus, the sublingual space is superomedial to the mylohyoid muscle and the submandibular space is inferolateral to the muscle. Ultrasound and MR can also be used to characterize these lesions. Ultrasound demonstrates a well-defined hypoechoic mass in the sublingual and submandibular space. MR images show the lesion with signal intensity of water, though if infected, signal intensity can vary according to the protein content or presence of hemorrhage with some wall enhancement.

The differential diagnosis would include epidermoid or dermoid cyst, lymphangioma or cystic hygroma, abscess, submandibular gland cyst (mucocele), and second branchial cleft cyst. These lesions differ in appearance on CT.

The treatment of a diving ranula is removal of the ipsilateral sublingual gland via the cervical or intraoral approach. It is not necessary to excise the pseudocyst since it puts the surrounding structures at risk for damage. Biopsy can be done to confirm the diagnosis.

Primary osteosarcoma of the mandible

Findings

There is destruction of the vertical ramus of the mandible on the left side with associated periosteal reaction and osteoid matrix (Figure 2 and Figure 3). Multiple lamellae are seen radiating from the lesion giving it a sunburst appearance. Also there is extension into the soft tissue of the face (Figure 1).


Diagnosis: Primary osteosarcoma of the mandible


Malignant tumors of the mandible can be grouped as odontogenic and non-odontogenic. Examples of non-odontogenic solid malignant tumors include sarcomas, metastases, multiple myeloma, lymphoma/leukemia, and squamous carcinomas. Osteosarcomas of the mandible are rare non-odontogenic tumors and account for 5-13% of all osteosarcomas.

Osteosarcomas of the jaw generally peak during the 3rd or 4th decade, as opposed to osteosarcomas of long bones which peak during adolescence. There is no conclusive gender predilection. It can be secondary to Paget disease, fibrous dysplasia and irradiation to the jaw. Clinically the patients present with painful jaw swelling.

Typical osteosarcomas show matrix mineralization, which may be osteoid or chondroid, with associated bone destruction and soft tissue extension. With large tumor size these signs are identified on a plain radiograph, and CT scan helps in describing the extent of involvement. For cases presenting early CT helps in identifying those missed with conventional radiography. Differentiating osteosarcomas from chondrosarcomas can be troublesome radiologically and sometimes even histopathologically; however chondrsarcomas are even rarer in the head and neck region.

Histologically, this tumor is less aggressive and less frequently high grade as compared to its conventional counterpart in the long bones. The spread of the disease to the cervical lymph nodes is seldom seen.

Osteosarcoma of the jaw should be treated with radical surgery as the primary modality. The single most important factor in curative therapy for osteosarcoma of the jaw is its amenability to radical resection with clear margins. Neoadjuvant chemotherapy is not used as a routine as against osteosarcoma of long bones. There is no general consensus over the role of radiation therapy in management of patients. In one study Delgado, et al. reported that when surgical margins are not free of disease, the use of radiation does not improve the outcome.

Trigonocephaly

Findings

CT 3D surface reconstructions show near-complete fusion of the metopic suture with trigonocephaly and "beaking" of the frontal bone along the midline. The sagittal, lambdoid, and coronal sutures are normal.


Diagnosis: Trigonocephaly


Craniosynostoses are calvarial dysmorphsims that result from premature closure of one or more sutures. Trigonocephaly, which involves the metopic suture, comprises less than 10% of all forms of craniosynostoses. It manifests prominent frontal keel, narrow forehead, and hypotelorism, which produces the appearance of a triangular skull. 3D CT reconstructions of the skull are well-suited for imaging the cranial sutures and osseous deformities. Trigonocephaly usually only poses an aesthetic concern and is amenable to reconstructive surgery. This craniosynostosis is infrequently associated with intracranial pathology or genetic disease such as Opitz "C" syndrome.

Orbital Dermoid

Findings

Figure 1 and Figure 2: Ovoid well-circumscribed ventromedial left orbital extraconal mass resulting in mass effect on the intraorbital contents displacing the globe laterally, demonstrating nonaggressive features. Internal areas of fat attenuation.

Figure 3and Figure 4: Ovoid well-circumscribed mass centered in the post-septal, extraconal left orbit which exerts mass effect on the left globe, displacing it laterally. Signal characteristics of the lesion are most consistent with an intraorbital dermoid, including fat signal layering within the nondependent portion of this predominantly cystic lesion. This fat floats on underlying proteinacous cystic material.


Diagnosis: Orbital Dermoid


Patients with this diagnosis generally complain of an orbital mass, which may be visible on physical examination. Growth of these lesions is generally slow. In adults, dermoids may become symptomatic for the first time and grow considerably over a year. Based on this fact, some authors have concluded that these lesions may be dormant for many years and/or have intermittent growth, such as in our case example.

Dermoids are the most common benign congenital lesion of the orbit, accounting for 1-2% of all orbital masses. Dermoid and epidermoid cysts are examples of choristomas, tumors that originate from aberrant primordial tissue. These tumors contain normal-appearing tissue in an abnormal location. As two suture lines of the skull close during embryonic development, dermal or epidermal elements are pinched off and form cysts, which are adjacent to the suture line. Approximately 50% of these tumors that involve the head are found in or adjacent to the orbit. They arise most often in the superolateral portion of the orbit at the frontozygomatic suture. They can also arise inferiorly, posteriorly, or medially (as in our case example). These lesions are extraconal and displace the globe. If the displacement is great, interference with vision by compression of the optic nerve may result or ocular motility may be disturbed, typically resulting in diplopia.

On MR the diagnosis is usually clinched with high signal on T1WI in the region which suppresses with fat saturation techniques. Fat may be seen floating in cystic fluid on T1WI.

These tumors are most often noted in young children; however, they may appear or grow at any age. In adults, they are more likely to displace the globe, possibly growing or eroding their way into adjacent