lecture 5 Developmental cysts

lecture 5 Developmental cysts

1. 1- Palatal cysts of the newborn

   • small keratin filled cysts (2-6)
     • 55% to 85% of neonates
       • Innocuous / self-healing
     • 1-3mm
     • stratified squamous
       • some communication with the mucosal surface
       • , white or yellow-white papules
   • Epstein’s pearl
     • median palatal raphe
     • arise from epithelium entrapped along the line of fusion of the palatal shelves.
   • Bohn’s nodule
     • scattered over the hard palate near the soft palate junction
     • arise from epithelial derived from minor salivary glands

2. 2- NASOLABIAL CYST (NASOALVEOLAR CYST)

   • rare
     • occurs in the in the soft tissues deep to the nasolabial fold.
       • origin
         • fusion of the maxillary, medial nasal, and lateral nasal processes
         • misplaced epithelium of the nasolacrimal duct
     • soft tissue> can't be seen in radiograph only by CT/MRI
   • a swelling of the upper lip lateral to the midline
     • elevation of the ala of the nose
       • May rupture spontaneously and drain into the oral cavity or nose
         • adults, 4th -5th / female predilection (3:1)
           • 10% bilateral
   • pseudostratified columnar epithelium+- goblet cells and cilia (respiratory type)
     • The cyst wall is composed of fibrous connective tissue with adjacent skeletal muscle.

3. 3- Nasopalatine duct cyst (incisive canal cyst):

   • most common non-odontogenic cyst of the oral cavit / 1% of the population
     • arise from remnants of the nasopalatine duct
       • 4th to 6th decades of life
         • Male
           • Biopsy is recommended
             • should be removed
     • symptomatic
       • Swelling of the anterior palate. Drainage ( if it raptures). Pain (in case of secondary infected).
     • Radiographs
       • near the midline of the anterior maxilla, between and apical to the central incisor teeth.
         • round or oval with a sclerotic border
           • pear shape, presumably because of resistance of adjacent
           • heart shape (this is not the true shape)
             • superimposition of the anterior nasal spine or because they are notched by the nasal septum
     • why it is hard to distinguish by radiograph
       • most cysts are in the range of 1.0 to 2.5 cm
         • incisive foramen can be 6mm
         • less than 6mm-6cm
     • cysts of the incisive papilla.
       • nasopalatine duct cyst develop in the soft tissues of the incisive papilla area without bone
         • bluish discoloration
     • Chronic inflammation of the wall is common
   • histology
     • near the nasal cavity: respiratory epithelium.
       • near the oral cavity : squamous epithelium
         • characteristic feature : neuromuscular bundles

4. 4- Median palatal(palatine) cyst

   • embryonic line of fusion of the palatal shelves of the maxilla
     • Positioned nasopalatine duct cyst
     • firm or fluctuant swelling of the midline of the hard palate posterior to the palatine papilla.
     • young adults
     • 2 × 2 cm
   • histology
     • stratified squamous epithelium
       • some ciliated pseudostratified columnar epithelium
     • no show large neurovascular bundles

5. 5- Follicular cysts of the skin:

   • keratin-filled
     • hair follicle
   • most common type come from the follicular infundibulum (shaft exists skin)
     • epidermoid cyst
       • midline floor of the mouth region are the simplest form of teratoma dermoid cyst
         • 80%
     • infundibular cyst
       • mouth XXX
   • after localized inflammation or obstruction of the hair follicle
     • or after traumatic implantation of epithelium
       • (rare) epidermal inclusion (implantation) cysts also can develop in the mouth.
         • occurs in the mouth
   • acne-prone areas >>
     • before puberty unless they are associated with Gardner syndrome
     • Young adults<< face older adults <<back
     • nodular, fluctuant subcutaneous lesion
   • histology
     • stratified squamous epithelium
       • Granules layer<< keratin hyaline<<maturation of the keratin<<epi disturbed << foreign body granulomatous inflammatory reaction

6. 6- Dermoid cyst

   • uncommon , dermal adnexal structures ,benign cystic form teratoma
     • children and young adult
       • 14% congenital
   • histology
     • orthokeratinized stratified squamous
       • prominent granular cell layer. / Abundant keratin / fibrous connective tissue wall /sebaceous glands, hair follicles, or sweat glands
   • location
     • most commonly occur in the midline of the floor of the mouth.
       • minimal manifestation of the teratoma-dermoid cyst epidermoid cyst spectrum
     • above the geniohyoid muscle
       • sublingual swelling may displace the tongue toward the roof of the mouth and create difficulty in eating, speaking, or even breathing
     • below the geniohyoid muscle
       • submental swelling, with a “double-chin” appearance

7. 7- Thyroglossal duct cyst (thyroglossal tract cyst)

   • Suggested stimuli:
     • inflammation: adjacent lymphoid tissue
     • Retention of secretions :func thyroid tissue/ secretions from epithelial itself
     • familial occurrence
   • develops
     • classically midline : foramen cecum area of the tongue to the suprasternal notch
     • 60%-80% adjacent to the hyoid bone
     • Suprahyoid cysts may be submental in location
     • thyroid cartilage deflected lateral to the midline because of the sharp anterior margin of the thyroid cartilage
     • Intralingual cysts are rare.
     • at base of the tongue may cause laryngeal obstruction
   • 50% : < 20.
     • painless, fluctuant, movable swelling
       • 3-10cm
         • if attachment to the hyoid bone or tongue<<move vertically during swallowing or protrusion of the tongue.
   • histology
     • columnar stratified squamous epithelium/ cuboidal epithelium/mixture +-Thyroid tissue in cyst wall

8. 8- Branchial cleft cyst(cervical lymphoepithelial cyst)

   • Incomplete obliteration of pharyngeal clefts and pouches //2nd branchial arch>> in upper lateral neck anterior or deep to the sternocleidomastoid muscle
     • most common area at the anterior border of sternocleidomastoid muscle
       • 10-40y // 1-10cm // as a soft, fluctuant mass
     • lesion becomes evident after an upper respiratory tract infection or trauma
   • histology
     • stratified squamous epithelium+- keratinized.>> respiratory epithelium.
       • The wall of the cyst: lymphoid tissue,germinal center formation

9. 9- Oral lymphoepithelial cyst

   • oral lymphoid tissue // <1cm
     • similar to cervical lymphoepithelial cyst but much smaller
       • Waldeyer ring:
         • palatine tonsils
         • lingual tonsils
         • pharyngeal tonsils
       • representive sites
         • Floor of the mouth. - Ventral tongue. - Posterior lateral border of the tongue.- Palatine tonsil. - Soft palate
   • firm or soft to palpation/ smooth and nonulcerated mucosa //white or yellow // most common in young adults.
   • histology
     • stratified squamous epithelium = parakeratinized + desquamated epithelial cells
       • lymphoid tissue in the cyst wall. +- Germinal centers

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