Chapter 15: Odontogenic cysts and tumors Flashcards
Dentigerous cyst
-‐ Most common developmental odontogenic cyst: dentigerous cyst
-‐ Fluid accumulation between reduced enamel epithelium and crown of tooth
-‐ Central, lateral and circumferential
-‐ Wall: glycosaminoglycan ground substance
-‐ Lining may give rise to ameloblastoma, SCC and mucoep (if mucous cells are present)
* Small dentigerous cyst vs enlarged follicle
–Radiolucent space around tooth crown should be at least 3-4mm in diameter to be dentigerous cyst
Eruption cyst
- ST counterpart DC.
- Soft, often translucent swelling in gingival mucosa overlying crown of erupting deciduous or permanent tooth
- Children < 10 yo
- Mandibular central incisors, 1st permanent molars, deciduous max incisors = most common
- If trauma occurs with hemorrhage -‐> eruption hematoma
Odontogenic keratocyst
-‐ Arises from dental lamina rests. New name: keratocystic odontogenic tumor (KCOT)
-‐ OKC: UL or ML RL post MD, 10-‐40 yo, 25-‐40% w/ impacted tooth. 30% recurrence (up to 10y)
-‐ May rarely undergo malignant transformation into SCC
- - Tend to grow in the anterior - posterior direction. No obvious bone expansion
Some suggests OKC be regarded as benign cystic neoplasm rather than a cyst - keratocystic odontogenic tumor (KCOT)
○ Greater expression of proliferating cell nuclear antigen (PCNA) and Ki-67 in suprabasilar layer
○ 30% of sporadic OKCs and > 85% of OKCs associated with nevoid basal cell carcinoma syndrome
○ Mutations of PTCH1 - Hedgehog signaling pathway
Orthokeratinized odontogenic cyst
-‐ Similar to OKC clinically. Epithelium lacks features of OKC. 2% recurrence
–young adults, posterior mandible
Nevoid basal cell carcinoma
-‐ Aka Gorlin syndrome: PTCH (9q22.3-‐q31) mutation.
-‐ BCC skin, multiple OKC, intracranial calcifications, bifid rib, kyphoscoliosis (curvature of spine), epidermoid cysts, hypertelorism, palmar/plantar pits, large head
-‐ BCC: less aggressive, younger age, blacks have less BCCs than whites
-‐ OKCs: more satellite lesions, solid islands of epith. proliferation and odont rests. Also overexpression of p53 and cyclin D1 (bcl-‐1)
Gingival cyst of the newborn
-‐ Remnants of Dental lamina rests.
-‐ Multiple whitish papules (keratin filled cysts) on MX alveolar process. Seen in up to 50% of newborns.
Gingival cyst of the adult
-‐ ST counterpart of LPC. Derived from rests of Serres (dental lamina)
-‐ May show clear cells (glycogen-‐rich cells)
Lateral periodontal cyst
-‐ Dental lamina rests.
– 5th through 7th decades of life, rarely occurs in individuals <30 yo
– RL MD canine-‐lat incisor-‐PM area
-‐ Botryoid odontogenic cyst: grape-‐like clusters of small individual cyst (polycystic/multilocular)
Calcifying odontogenic cyst (Gorlin cyst)
-‐ 20% associated with odontoma; also seen with AOT, ameloblastoma and ameloblastic fibroma
-‐ 30% peripheral.
-‐ MD=MX, anterior region, mean age 30 yo. UL or Ml RL, 30-‐50% w/ calcifications, 30% unerupted tooth (canine)
-‐ Cystic (98%) or neoplastic (2%)
-‐ Solid: similar to AB, but w/ ghost cells and dentinoid (dentinogenic or epithelial odontogenic ghost cell tumor) (intraosseous or peripheral-‐latter more common)
-‐ May rarely transform into SCC
-‐ Odontogenic ghost cell carcinoma (tumor): malignant/aggressive odontogenic ghost cell tumor
-‐ Skin analogue: pilomatrixoma (calcifying epithelial tumor of Malherbe, usually scalp)
Glandular odontogenic cyst
-‐ Anterior MD, crossing midline. 30% recurrence
-‐ Hobnail or papillary epithelial lining, cilia, mucicarminophilic material, mucous cells, spherical nodules (similar to LPC)
– Middle-aged adults (46 - 51 yo), rarely before 20
– * 9 criteria
○ Flat epithelial interface
○ Focal luminal projections
○ Hobnail cells
○ Mucous/goblet cells
○ Ducts
○ Papillary projections
○ Ciliated cells
○ Multicystic/multiluminal
○ Clear cells in basal layer
Buccal bifurcation cyst
-‐ Buccal of mandibular first molar. Lingual displacement of roots on occlusal.
-‐ Enamel extension in bifurcation can predispose tooth to pocket and cyst formation
-‐ May arise by an inflammatory response during tooth eruption
-‐ Paradental cyst: distally to partially erupted third molar
Carcinoma arising in odontogenic cysts
-‐ Arises de novo, from AB, from odontog tumor, or odontog cyst (DC, OKC, OOC, LPC)
-‐ Most common pattern in a residual periapical cyst. Must R/O met
Ameloblastoma
-‐ Origin from dental lamina, enamel organ, lining of cyst or basal cell of mucosa
-‐ Desmoplastic ameloblastoma: anterior MX. Mixed RL/RP [(~ BFOL (COD)]. Histology ~ met
-‐ Histology: follicular, plexiform, acanthomatous, granular cell, desmoplastic, basal cell, clear cell
-‐ Granular cell ameloblastoma: more aggressive; younger patients; contains lysossomes
-‐ Desmoplastic ameloblastoma: TFG-‐beta increased. Inductive effect around islands and myxoid elsewhere.
-‐ Unicystic ameloblastoma: patients younger than multicystic. Histo: luminal, intraluminal, mural
-‐ Plexiform unicystic ameloblastoma: nodules similar to plexiform amelob prolif into lumen
-‐ Unicystic: if histology shows mural, new sx should be performed
-‐ Vickers-‐Grolin criteria to define unicystic amelo: (1) columnar basilar cells, (2) palisading of basilar cells, (3) polarization of basilar layer nuclei away from the basement membrane, (4) hyperchromatism of basal cell nuclei in the epithelial lining, and (5) subnuclear vacuolization of the cytoplasm of the basal cells.
-‐ Peripheral amelob: nodule in post gingiva. DDx: P odontog Fibroma (has dentin or cementum-‐ like material and lacks reverse polarity). May rarely undergo malignant transform
Malignant ameloblastoma and ameloblastic carcinoma
-‐ Malignant ameloblastoma: normal histo in both primary and met. Mean age 30 yo. Met usually lung 10y after first dx
-‐ Ameloblastic carcinoma: cytologic features of malignancy. Older pts.
Clear cell odontogenic carcinoma
-‐ Glycogen-‐rich pre-‐secretory ameloblasts.
-‐ Three patterns: monophasic, biphasic (clear/epithelial) and clear cell ameloblastoma-‐like.
-‐ DDx: mucoep (mucicarmine +), CEOT (amyloid +) and metastatic cancer (renal, breast, melanoma - panel)
– rearrangements of EWSR1 gene in clear cell odontogenic carcinoma
This alteration can often be seen in hyalinzing clear cell carcinoma
