Non-Odontogenic Cysts
* **Developmental**
* Lymphoepithelial cyst
* Presentation / Progression
* OKC with lymphoid tissue in wall
* Occurs at the sites of lymphoid tissue
* Commonly FOM, lateral & posterior tongue and tonsil pillars
* Pathophysiology
* Arises from entrapment of epithelium within lymph nodes or lymphoid tissue during development
* Blind ended epithelial invagination into lymphoid tissue that may lead to a tract that become filled with keratin
* Histology
* Lined by parakeratinised stratified squamous epithelium (Similar to OKC)
* Epithelial lining surrounded by discrete lymphoid component
* Cyst wall contains variable proportions of lymphocytes, macrophages and plasma cells
* Cyst lining may be continuous with surface epithelium
* Treatment
* Thyroglossal duct cyst
* Presentation / Progression
* Most common developmental cyst of the neck
* 7% of the population
* Any age
* Midline lesion but 20% para-median
* Moves with tongue on protrusion
* Imaging
* Thyroid scan - Iodine 131
* Determines presence of thyroid tissue in neck or lingual thyroid
* US - can show tract and lesion
* Pathophysiology
* Remnant of epithelial cells from the descent of thyroid gland
* Thyroid develops around Foramen cecum - 3 to 4 weeks
* Descends - 4 to 8 weeks
* Involution of duct - 8 to 10 weeks
* Distal portion may persist at the pyramidal lobe in up to 50% of the population
* Histology
* Lining of psudostratified columnar epithelium
* Frequently contain thyroid follicles and thyroid colloid
* Treatment
* Sistrunk procedure
* Excison of cyst and entire tract all the way up to tongue
* Centre of hyoid bone usually invovled in excision
Can excise lesion from periosteum as an alternative
* Ligation of duct as far proximal as possible
* Recurrence is rare
* Branchial cleft cyst
* Presentation / Progression
* Also known as cervical lymphoepithelial cyst
Contains epithelial cells and lymphoid tissue/germinal centres
* 20 - 30 yr old
* II branchial arch - 95%
* Bailey Classification for II arch cysts
* Based on depth
* I - Deep to platysma
* II - Superficial to Carotidy body
* III - Passing between Carotid arteries
* IV - On pharyngeal wall
* I - 5%
* Incidental finding or activation of activation of lymphoid tissue during infection
* Branchial arches cleft cyst locations:
* I - Near angle of mandible. Can extend to auricle
* II - Located anterior to SCM (Inf and mid third)
* III - Extend from SCM (Inf and mid third) to piriform fossa
* IV - Parallels the course fo the recurrent laryngeal nerve. Begins at the piriform fossa and extend to the thyroid
* Pathophysiology
* Two theories
* Cleft between branchial arches fails to completely involute
* Cystic transformation of cervical lymph nodes
* Histology
* Lined by SSE
* Lymphocytes and germinal centres
* Same as lymphoepithelial cyst - cystic degeneration of lymph node
* Treatment
* Sclerotherapy with Picibanil
* Surgery
* Excision and ligation of residual tract
* Dermoid cyst
* Presentation / Progression
* Dermoid cyst contains adnexal structures
cf Epidermoid cyst (Sebaceous cyst) - Epithelial cells
* Most common site is the lateral brow
* Asymptomatic swelling
* Pathophysiology
* Improper fusion of skin layers
* Histology
* Line by SSE
* Fibrous connective tissue wall
* Contain adnexal structures
* Hair follicles
* Sebaceous glands
* Sweat glands
* Teratoid variety includes elements of all germ cell layers
* Teeth
* Bone
* Muscle
* Treatment
* Surgical excision
* Recurrence is rare
* **Acquired**
* Simple bone cyst / Solitary bone cyst
* Presentation / Progression
* Not a true cyst - Lacks epithelial lining
* Occurs in younger patients
* Asymptomatic
* No bony expansion
* Vital dentition
* Radiolucent lesion with sclerotic bone that scallops around the teeth
* Pathophysiology
* FITH
* Fibro-osseous lesion resolving
* Ischaemia - Necrosis leading to interruption of venous drainage leading to increased intramedullary pressure which triggers osteoclastic bone resorption
* Trauma - Intramedullary hemarrhage which resolves but is not replaced with bone
* Hormones - changes during teenage years cause disturbances in remodelling of trabecular bone
* Histology
* Bone cavity with no epithelial lining
* Serosanguinous material in the lumen
* Treatment
* Exploration and currettage the bone wall to stimulate bleeding and bone infill
* Nasopalatine duct cyst
* Presentation / Progression
* Most common non-odontogenic cyst
1% of population
* M\>F
* 30 - 50 yrs of age
* Asymptomatic soft swelling of the anterior hard palate
* Vital teeth
* Root resorption is rare
* Fluctuating painful swelling can occur due to secondary infection
* Imaging
* Heart shaped appearance
* Occurs between the central incisors
* 7mm cut-off (Roper-Hall 1938)
* Pathophysiology
* Nasopalatine ducts runs either side of the nasal septum and exite at the incisive canal
* Epithelial remnants of nasopalatine duct that have failed to degenerate can form cysts
* Infection or trauma can stimulate cyst formation
* Histology
* Epithelial lined cyst
* Stratified squamous or Cuboidal or Columnar
* Pseudostratified columnar
* Higher up in canal - More features of respiratory epithelium
* Can have nerves, arteries, veins and minor salivary gland
* Treatment
* Enucleate
* Recurrence is very low
* Median palatal fissure cyst
* Presentation / Progression
* Fissural cyst due to the entrapment of epithelium along fusion line of lateral palatal shelves
* Firm fluctuant swelling in midline of hard palate and posterior incisive canal
* Can be difficult to distinguish from a posteriorly located Nasopalatine duct cyst
* Pathophysiology
* Due to the entrapment of epithelium along fusion of the lateral palatal shelves
* Histology
* Stratified squamous epithelium
* No nerves, arteries or veins
* Treatment
* Excision
* Recurrence low
* Nasolabial cyst
* Presentation / Progression
* 30 - 40 yr olds
* 10% bilateral
* M \< F - 1:4
* Nasolabial swelling
* Anywhere from alar crease to labial vestibule
* Asymptomatic
* Fluctuant
* Pathophysiology
* Two theories
* Entrapped epithelial remnants at the junction of maxillary medial and lateral nasal processes
* Ectopic epithelium of the Nasolacrimal duct
* Deep to muscles of facial expression
* May have respiratory epithelium
* Histology
* Line by pseudostratified columnar epithelium +/- goblet cells
* Fibrous connective tissue wall
* Treatment
* Extracapsular excision
* Can be performed trans-cutaneously or trans-orally if close to nasal floor
* Part of the nasal mucosa may require excision
* Mucous retention cyst
* Presentation / Progression
* True cyst - cf Mucous extravasation cyst
* Asymptomatic swelling
* Painful if infected
* Pathophysiology
* Obstruction of salivary duct that causes pooling of saliva and distension of the duct and or gland
* True cyst - lined by epithelium
* Histology
* Lined by cuboidal, columnar, squamous cells
* Mucoid secretions
* Dilated ducts
* Treatment
* Excise if isolated
* If within major gland - may require gland removal
* Surgical ciliated cyst
* Presentation / Progression
* 30 - 40 yr olds
* Occurs post trauma or surgery
* Asymptomatic swelling
* Pathophysiology
* Occurs post trauma or surgery
* Respiratory epithelium is trapped in foreign tissue in surgical site
* Histology
* Lined by respiratory epithelium
* Pseudostratified columnar epithelium
* Treatment
* Excision of cyst