Epithelial Remnants Derivatives

Why do these remnants proliferate?
The origin of epithelial odontogenic neoplasms, hamartomas and cysts is inextricably bound up with a discussion of the parent cells of these lesions.

Epithelial Remnants may develop into Cysts, Tumors, and Hamartomas.

1. Epithelial Remnants
Derivatives
Ahmad AmroBaradee

2. Definition
•The epithelial remnants are the rests of an epithelia
that served once as a meaningful tissue in embryonic
life or during the tooth formation.
•While this epithelial cells are supposed to disintegrate due
to ectomesenchymalinvasion and/or programmed cell
death, others persist !!
•These Remnants may develop into Cysts, Tumors, and
Hamartomas.

5. Rests of Malassez

6. Reduced enamel epithelium

7. Rests of Serres
(Remnants of dental lamina)

8. Why do these remnants proliferate?
It is widely held that the majority of epithelial residues persist
throughout life as vital, by large inactive (resting) single cells or cell
clusters. Some of the cell rests seem to be triggered to proliferation by
hitherto unknown mechanisms (apart from instances of possible
inflammatory stimuli), resulting in production later in life of well-
recognized pathological entities.
The origin of epithelial odontogenicneoplasms, hamartomasand cysts is
inextricably bound up with a discussion of the parent cells of these
lesions.

9. •RadicularCyst (+ Residual + Lateral)
Rests of
Malassez
•ParadentalCyst (Craig 1976)
•Calcifying OdontogenicCyst(Prætoriuset al. 1981)
•Dentigerouscyst
•Eruption Cyst
Reduced
enamel
epithelium
•Odontogenickeratocyst
•Lateral periodontal Cyst
•Gingival Cyst
•Glandular odontogenicCyst
Rests of
Serres
cysts originated from odontogenicepithelial remnants

11. •Ameloblastomas
•SquamousOdontogenicTumour
Rests of
Malassez
•Ameloblastomas
Reduced
enamel
epithelium
•Ameloblastomas(Peripheral Ameloblastoma)
•SquamousOdontogenicTumour
•Calcifying Epithelial OdontogenicTumor
•AdenomatoidOdontogenicTumour
•KeratinisingCystic OdontogenicTumour
•OdontogenicGingival Epithelial Hamartoma
Rests of
Serres
Tumoursoriginated from odontogenicepithelial remnants

13. •Arises from epithelial remnants of
the embryonic thyroglossalduct.
Thyroglossal
tract cyst
•Arises from epithelial remnants (of the
branchialarches or of salivary origin) within
cervical lymph nodes.
Branchial
cleft cyst
•Arises from epithelial remnants of the
embryonicnasopalatineduct.
Nasopalatine
Canal Cyst
Derivatives of other epithelial remnants in H&N

14. •Arises from epithelial remnants of the
lower part of the embryonic
nasolacrimalduct.
Nasolabial
Cyst
•Arises from epithelial remnants in the midline
during closure of 1
st
& 2
nd
branchialarches
Dermoid&
Epidermoid
cyst
•Arises from salivary epithelium
remnants in extracapsularlymphnodes
Warthin’s
Tumour
Derivatives of other epithelial remnants in H&N

15. In recent years, the existence of this group of lesions as separate entities has
been questioned and they were excluded from the 1992 WHO Classification of
epithelial jaw cysts (Kramer et al., 1992).
Previously,it had been thought that these cysts developed from epithelium
entrapped in the process of fusion of embryonic processes.
It is nowbelieved that they represent :
-posterior extension of an incisive canal cyst in the case of median palatine cyst;
-anterior extension in the case of median alveolar cyst;
-and a range of other odontogeniccysts, frequently an odontogenickeratocyst, in
the case of the globulomaxillarycysts.
-Moreover, the so-called median alveolar cyst may also, in a number of instances,
be a keratocystderived from dental lamina in the midline of the maxilla.
“NOTE ON THE SO-CALLED :MEDIAN PALATINE,MEDIAN
ALVEOLAR,MEDIAN MANDIBULAR ANDGLOBULOMAXILLARY
CYSTS”

16. Radicular
Cyst
Paradental
Cyst
Dentigerous
Cyst
Eruption
Cyst

17. Odontogenickeratocyst
Lateral periodontal CystGingival Cyst
Glandular odontogenicCyst

18. Ameloblastoma Calcifying OdontogenicCyst
Peripheral AmeloblastomaSquamousOdontogenicTumor

19. Calcifying Epithelial
OdontogenicTumour
Adenomatoid
OdontogenicTumour

20. OdontogenicGingival
Epithelial Hamartoma
Dermoid& Epidermoidcyst
KeratinisingCystic
OdontogenicTumour

21. Thyroglossal
tract cyst
Branchialcleft cyst
NasolabialCyst NasopalatineCanal Cyst

22. References
•PhilipsenHP, ReichartPA . The Development
and Fate of Epithelial Residues after
Completion of the Human Odontogenesiswith
Special Reference to the Origins of Epithelial
OdontogenicNeoplasms, Hamartomasand
Cysts. Oral BiosciMed.2004; 1: 171-179.
•RegeziJA, SciubbaJJ, Jordan RCK. Oral
Pathology: Clinical Pathologic Correlations, 5th
ed.St. Louis: Saunders; 2007.
•SoamesJV, SouthamJC. Oral pathology, 4th
ed.New York, Oxford University Press 2005.
•Shear M, Speight P. Cysts of the Oral and
Maxillofacial Regions 4th ed. Oxford: Blackwell
Munksgaard2007.
•Neville BW, DammDD, White DH. Color Atlas
of Clinical Oral Pathology 2nd ed. Ontario: BC
Decker 2003.

23. Questionnaire Session