Dermoid Cyst in Submandibular Space: Imaging Findings and Diagnosis

1. CASES DR. HIRAL THAKKAR IIND YEAR RESIDENT DEPT. OF RADIODIAGNOSIS

2. CASE 1

3. A 4 Year old male presented with complaint of painless neck mass. • CT Scan was performed

4. Cystic mass with multiple septations located anterior to the right sternocleidomastoid muscle and extending inferiorly from the level of the hyoid. There is mild displacement of right carotid and jugular vessels as well as the trachea.

5. Differential diagnosis: Of submandibular space lesions include • Congenital lesions • cystic hygromas, • branchial cleft cysts, • dermoid & epidermoid, • thyroglossal duct cysts. • lymphadenopathy • Ranula • Abscesses

6. DERMOID CYST • It usually manifest during the 2nd and 3rd decades of life with no gender predilection. • Only 7% of dermoid inclusion cysts occur in the head and neck, with the lateral eyebrow being the most common location. About 11% of dermoid cysts of the head and neck are in the floor of the mouth, the second most common location & the most common cervical location of a dermoid cyst. • Clinical signs and surgical approach are determined by the relationship of the cyst to the musculature of the floor of the mouth. • This information is crucial for optimal preoperative planning.

7. They appear as moderately thin-walled, unilocular masses, located in the submandibular or sublingual space. • On CT scans, the central cavity is usually filled with a homogeneous, hypoattenuating (0–18 HU) fluid material. • It may appear to be filled with "marbles," due to the coalescence of fat into small nodules within the fluid matrix. This "sack-of-marbles" appearance is virtually pathognomonic for a dermoid cyst in this location. • It may be heterogeneous on CT scans because of the various germinal components. Fluid-fluid levels with supernatant lipid are possible. • The rim of these cysts often enhances following administration of contrast material.

8. Axial CECT scan shows a well-defined mass in the submandibular-submental region with multiple discrete foci of hypoattenuation in the nondependent portion of the cyst. Coronal CT scan shows the mass inferior to the mylohyoid muscle (arrowheads).

9. MR imaging depicts the topographic relationship of these cysts to the mylohyoid muscle in the floor of the mouth and helps determine the surgical approach. • The coronal plane is optimal for determining the location of the mass with respect to this muscle pair. • Dermoid cysts have variable signal intensity on T1-weighted images. They may be hyperintense (because of the presence of sebaceous lipid) or isointense relative to muscle on T1-weighted images. They are usually hyperintense on T2-weighted images. • The mass has a clearly demarcated rim but frequently has a heterogeneous internal appearance.

10. Coronal T1W

11. EPIDERMOID CYSTS • They are rare congenital lesions and are much less common than dermoid cysts in the head and neck. They appear earlier than dermoid cysts, with most lesions evident during infancy • They have fluid attenuation on CT scans and are hypointense on T1-weighted images and hyperintense on T2-weighted images, following the signal intensity of fluid. • An epidermoid cyst located entirely within the sublingual space may be difficult to distinguish from other cystic lesions in the floor of mouth (e.g., a simple ranula) on the basis of imaging criteria alone

12. The essential difference between a dermoid cyst and an epidermoid cyst lies in the presence of skin appendages (e.g., sebaceous glands, hair follicles) within the wall of the dermoid cyst and the absence of these features in the epidermoid cyst. • A teratoid cyst may also contain tissue of other major organ systems (e.g., nervous, gastrointestinal, respiratory).

13. TERATOID CYSTS • 5% of teratomas in newborns situated in the lateral and anterior cervical region. • CT may show a hypoattenuating, thin-walled unilocular mass. • At MR imaging, they are hypo- to isointense on T1-weighted images and hyperintense on T2-weighted images.

14. Mature neck teratoma in a 9-month-old boy. (a) Axial proton-density–MR image shows a hyperintense subcutaneous mass in the right side of the neck (arrow). (b) Coronal T2-weighted MR image shows multiple cysts with heterogeneous signal intensity (arrowheads). PD AXIAL IMAGE CORONAL T2W IMAGE

15. ABSCESS • Abscesses are usually rapidly developing and painful and may be associated with fever and leukocytosis. • Abscesses frequently involve the nodal groups draining the primary site of infection. • A third of cases of suppurative cervical lymphadenopathy are associated with pharyngitis and tonsillitis, a third with dental infection, and a third with dermatologic and otologic infection. • Imaging distinguishes the ill-defined edema of cellulitis from the coalesced and cystic abscess requiring surgery. • Abscesses frequently have thick ring-configured enhancement and may be multiloculated. Untreated infection may dissect along fascial planes.

16. Enhanced CT demonstrates confluent, necrotic submandibular lymph nodes (asterisk) draining the site of an infected dental procedure. The subcutaneous fat is infiltrated (arrow) and the airway is encroached on.

17. THYROGLOSSAL CYST • Most common congenital anomaly of the neck • 2-4% of all neck masses • Over half present in the first decade of life but may also be seen in adults • There is an equal gender distribution, and they are usually asymptomatic. • Pyramidal lobe of the thyroid is the most common remnant of the thyroglossal tract (50% of population)

18. Etiology • Represents a persistent epithelial tract during the descent of the thyroid from the foramen cecum to its final position in the anterior neck. • Normally this duct obliterates by week 10 of development. • Histologically • Well-defined cyst with an epithelial lining composed of either squamous or respiratory epithelium • There can sometimes be islands of thyroid tissue lying in the walls of the cysts • Cysts are filled with mucoid or mucopurulent material, depending on whether the cyst has been infected

19. Types of thyroglossal duct cysts • Infrahyoid type • 65% and is mostly found in the paramedian position • Suprahyoid type • Nearly 20% and is positioned in the midline • Juxtahyoid cysts (15% ), Intralingual location (2%), Suprasternal variety (10% ), Intralaryngeal (Very rare ) • Clinical • Nontender and mobile masses • Infected cysts may manifest as tender masses with • Dysphagia, Dysphonia, Draining sinus, Fever, Enlarging neck mass • Often appear after an upper respiratory tract infection • Airway obstruction possible, especially with intralingual cysts • The pathognomonic sign is that the cyst moves with tongue protrusion

20. Radiologic Features: • On all radiologic images, a thyroglossal duct cyst manifests as a cyst like mass either in the midline of the anterior neck at the level of the hyoid bone or within the strap muscles just off the midline. • At US, the finding of an anechoic mass with a thin outer wall in this characteristic location easily establishes the diagnosis of a thyroglossal duct cyst. However, this "classic" appearance is seen in less than half of the cases.

21. More commonly, these cysts manifest as hypoechoic masses, often with increased through-transmission. • They may be either homogeneous or heterogeneous in appearance with variable degrees of fine to coarse internal echoes. • Heterogeneity seen in thyroglossal duct cysts on sonograms is more likely due to the proteinaceous content of the fluid secreted from the cyst wall rather than to infection. • Preoperative sonographic visualization of normal thyroid tissue is sufficient to exclude a diagnosis of ectopic thyroid tissue and obviates routine thyroid scintigraphy.

22. On CT scans, usually appears as a smooth, well-circumscribed mass anywhere along the vertical course of the vestigial thyroglossal duct. • The mass has a thin wall and homogeneous attenuation, the values of which correspond to those of fluid (10–18 HU). • Elevated attenuation values of the fluid cyst reflect its increased protein content and generally correlate with a history of prior infections. • Peripheral rim enhancement is usually observed on contrast-enhanced scans.

23. On MRI, an uncomplicated thyroglossal duct cyst has low signal intensity on T1-weighted images and is hyperintense on T2-weighted images, findings that reflect its fluid content. • The rim will be non-enhancing unless inflammation is present. • In case of infection or hemorrhage, a thick irregular rim may be visualized, and the signal intensity of the fluid becomes variable from the presence of proteinaceous debris.

24. Thyroglossal duct cyst at & above the hyoid bone.

25. Infrahyoid & paramedian thyroglossal duct cysts

26. Complications • Infection is probably the most common complication • Local growth and invasion is extremely uncommon • Carcinoma is extremely rare • Occurs in about 1% to 2% of patients • Thyroid ectopia • Fewer than 5% of these cysts actually have ectopic thyroid tissue

27. 2ND BRANCHIAL CLEFT CYST • Over 90% of branchial anomalies arise from the second branchial apparatus, with a predominance of cysts. • Most second branchial cleft cysts are located in the submandibular space, at the anteromedial border of the sternocleidomastoid muscle, lateral to the carotid space, or posterior to the submandibular gland. • They appear as painless fluctuant masses adjacent to the anterior border of the sternocleidomastoid muscle at the mandibular angle.

28. The cysts usually occur in patients between 10 and 40 years of age, but fistulas or sinuses are more commonly found during the 1st decade of life. • There is no gender predilection. • The walls of the cysts are usually lined with stratified squamous epithelium overlying lymphoid tissue and occasionally with columnar respiratory epithelium. The intracystic fluid may contain cholesterol crystals.

29. USG- • It is seen as a sharply marginated, round to ovoid, centrally anechoic mass with a thin peripheral wall that displaces the surrounding soft tissues. • The mass is compressible and shows distinct acoustic enhancement. • Occasionally, fine, indistinct internal echoes, representing debris, may be seen.

30. CT & MRI: • Typically well-circumscribed, homogeneously hypoattenuated masses surrounded by a uniformly thin wall, typically do not enhance. • They are hypo- to isointense on T1-weighted images and is hyperintense on T2-weighted images. • The mural thickness may increase after infection. • The "classic" location of these cysts (at either CT or MR imaging) is at the anteromedial border of the sternocleidomastoid muscle, lateral to the carotid space, and at the posterior margin of the submandibular gland.

31. The cyst typically displaces the sternocleidomastoid muscle posteriorly or posterolaterally, pushes the vessels of the carotid space medially or posteromedially, and displaces the submandibular gland anteriorly. • Extension of the mass between the external and internal carotid arteries is very suggestive of a second branchial cleft cyst regardless of its relation to the sternocleidomastoid muscle.

32. INFECTED BRANCHIAL CYST

33. AXIAL T2W IMAGE AXIAL T1W IMAGE

34. RANULAS • They are sublingual salivary gland retention cysts and by definition arise in the sublingual space. • Simple ranulas are confined to the floor of the mouth. • Plunging ranulas dehisce either through or posterior to the mylohyoid muscle and spill into submandibular and parapharyngeal spaces. • Magnetic resonance imaging is ideally suited for characterizing floor of the mouth cystic lesions.The MRI appearance of ranulas is usually cystic; however, signal intensity varies with the protein or hemorrhagic contents of the ranula.

35. CECT shows bilobed thin walled cystic arising in the Lt sublingual space & extending into the submandibular space.

36. CYSTIC HYGROMA • It is the most common form of lymphangioma and constitutes about 5% of all benign tumors of infancy and childhood. • The majority (about 80%–90%) are detected by the time the patient is 2 years old. No gender predilection has been reported. • In children, the most common location is the posterior cervical space, followed by the oral cavity. • They are characteristically infiltrative in nature and do not respect fascial planes. Consequently, they may extend inferiorly from the posterior cervical triangle into the axilla and mediastinum or anteriorly into the floor of the mouth and the tongue. If the mass is very large, it may extend across the midline.

37. On US scans, most cystic hygromas manifest as a multilocular predominantly cystic mass with septa of variable thickness. • The echogenic portions of the lesion correlate with clusters of small, abnormal lymphatic channels. • Fluid-fluid levels can be observed with a characteristic echogenic, hemorrhagic component layering in the dependent portion of the lesion.

38. On CT images, cystic hygromas tend to appear as poorly circumscribed, multiloculated, hypoattenuated masses. • They typically have characteristic homogeneous fluid attenuation. • Infected lesions commonly show higher attenuation than that seen in simple fluid. • Usually, the mass is centered in the posterior triangle or in the submandibular space It is not uncommon for some of these lesions to extend from one space in the neck into another as a result of their infiltrative nature.

40. MR imaging allows the best differentiation between lymphatic malformations and the surrounding soft tissues, with the former demonstrating low or intermediate signal intensity on T1-weighted images and hyperintensity on T2-weighted images. • The walls of the septa may enhance after intravenous injection of gadopentetatedimeglumine. • Infrequently, it may be hyperintense on T1-weighted images, a finding associated with clotted blood or high lipid (chyle) content. In the case of hemorrhage, fluid-fluid levels may be observed.

41. T2-w MR images and an axial fat-saturated post Gd T1-w image obtained show a multiloculated cystic mass in the left posterior triangle of the neck (arrow). The cysts are hyperintense on the T2-weighted images and demonstrate peripheral wall enhancement on the T1-weighted image.

42. 2ND BRANCHIAL CLEFT CYST 3 & 4th decade of life Classic location: anteromedial border of SCM muscle, lateral to carotid space & posterior to SM gland. On CT: homogenous hypoattenuating mass with thin wall whiach typically do not enance. DERMIOD CYST 2 & 3RD decade of life On CT: central cavity with homogenous hypoattenuating fluid material with sack of marbles appearance which is pathognomonic. MRI: hyperintense but hetrogenous. EPIDERMOID CYST Rare Infant age group On CT homogeonous fluid attenuating ON MRI: hypointense on T1 and hyperintense on T2 ABSCESS Rapidly developing and painful lesion Ass. With fever and leucocytosis Thick ring configured enhancement and may be multiloculated THYROGLOSSAL DUCT CYST C’n location is midline 1st decade On CT: smooth well defined circumscribed mass along the vertical course of vestigeal TGD with thin wall, homogenous fluid attenuation and peripheral rim enhancement. CYSTIC HYGROMA Most c’n form of lymphangioma < 2 yrs of age Infilterative in nature Multilocular cystic lesion with fluid – fluid levels if there is haemorrhage RANULA Seen extending into sublingual space

43. Cystic mass with multiple septations located anterior to the right sternocleidomastoid muscle and extending inferiorly from the level of the hyoid. There is mild displacement of right carotid and jugular vessels as well as the trachea. • Thus in our case

44. Most likely DIAGNOSIS is: CYSTIC HYGROMA

45. CASE2

46. A 26 yrs old male presented with complaint of pain in left shoulder after lifting a heavy weight. • His x-ray of left shoulder was taken which revealed…

47. Shows slightly expansile, septated lytic lesion is present involving the proximal 1 /3rd of the left humerus. The margins are not sclerotic. The epiphysis appears uninvolved.

48. The most likely differentials would be: • Unicameral bone cyst • Aneurysmal bone cyst • Enchondroma • Fibrous dysplasia • Myxoid fibroma.

49. ANEURYSMAL BONE CYST • Aneurysmal bone cyst (benign bone aneurysm) is a solitary benign osteolytic lesion expanding a long bone or within a vertebra, consisting of blood-filled spaces, and separated by fibrous tissue containing multinucleated giant cells causing swelling, pain, and tenderness. • ABC predilects 5- 20 years old individuals. • The most common locations include: Posterior elements of the spine, Clavicle, Metaphysis of long bones • There are two types of ABC’s: primary and secondary • Primary has no known cause or association with it. • Secondary type occurs in conjunction with another lesion or from trauma. 

50. RADIOGRAPHIC APPEARANCE: Radiographs: -The classical lesion is an eccentric expanding lytic lesion in the metaphysis of a child, -aneurysmal expanded appearance of cortex is contained by periosteum & thin egg- shell covering of expanded cortex over the surface of the lesion. -Lesion rarely penetrates the articular surface or growth plate; -cyst often shows apparent trabeculation usually due to over riding of endosteal cortex. -In diaphysis, an intracortical or subperiosteal site is sometimes seen producing a superficial blister. • Spine: • radiographs demonstrate loss of pedicle of involved vertebrae and some displacement of the soft tissues by the mass;in the spine ABC’s usually involve one side of vertebral arch. posterior elements of the vertebrae are a frequent location;