Epithelial Remnants Derivatives

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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.

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Epithelial Remnants Derivatives

  1. 1. Epithelial Remnants Derivatives Ahmad Amro Baradee
  2. 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 ectomesenchymal invasion and/or programmed cell death, others persist !! • These Remnants may develop into Cysts, Tumors, and Hamartomas.
  3. 3. Rests of Malassez
  4. 4. Reduced enamel epithelium
  5. 5. Rests of Serres (Remnants of dental lamina)
  6. 6. 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 odontogenic neoplasms, hamartomas and cysts is inextricably bound up with a discussion of the parent cells of these lesions.
  7. 7. • Radicular Cyst (+ Residual + Lateral) Rests of Malassez • Paradental Cyst (Craig 1976) • Calcifying Odontogenic Cyst(Prætorius et al. 1981) • Dentigerous cyst • Eruption Cyst Reduced enamel epithelium • Odontogenic keratocyst • Lateral periodontal Cyst • Gingival Cyst • Glandular odontogenic Cyst Rests of Serres cysts originated from odontogenic epithelial remnants
  8. 8. • Ameloblastomas • Squamous Odontogenic Tumour Rests of Malassez • Ameloblastomas Reduced enamel epithelium • Ameloblastomas (Peripheral Ameloblastoma) • Squamous Odontogenic Tumour • Calcifying Epithelial Odontogenic Tumor • Adenomatoid Odontogenic Tumour • Keratinising Cystic Odontogenic Tumour • Odontogenic Gingival Epithelial Hamartoma Rests of Serres Tumours originated from odontogenic epithelial remnants
  9. 9. • Arises from epithelial remnants of the embryonic thyroglossal duct. Thyroglossal tract cyst • Arises from epithelial remnants (of the branchial arches or of salivary origin) within cervical lymph nodes. Branchial cleft cyst • Arises from epithelial remnants of the embryonic nasopalatine duct. Nasopalatine Canal Cyst Derivatives of other epithelial remnants in H&N
  10. 10. • Arises from epithelial remnants of the lower part of the embryonic nasolacrimal duct. Nasolabial Cyst • Arises from epithelial remnants in the midline during closure of 1st & 2nd branchial arches Dermoid & Epidermoid cyst • Arises from salivary epithelium remnants in extracapsular lymphnodes Warthin’s Tumour Derivatives of other epithelial remnants in H&N
  11. 11. 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 now believed 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 odontogenic cysts, frequently an odontogenic keratocyst, in the case of the globulomaxillary cysts. - Moreover, the so-called median alveolar cyst may also, in a number of instances, be a keratocyst derived from dental lamina in the midline of the maxilla. “NOTE ON THE SO-CALLED : MEDIAN PALATINE, MEDIAN ALVEOLAR, MEDIAN MANDIBULAR AND GLOBULOMAXILLARY CYSTS”
  12. 12. Radicular Cyst Paradental Cyst Dentigerous Cyst Eruption Cyst
  13. 13. Odontogenic keratocyst Lateral periodontal CystGingival Cyst Glandular odontogenic Cyst
  14. 14. Ameloblastoma Calcifying Odontogenic Cyst Peripheral AmeloblastomaSquamous Odontogenic Tumor
  15. 15. Calcifying Epithelial Odontogenic Tumour Adenomatoid Odontogenic Tumour
  16. 16. Odontogenic Gingival Epithelial Hamartoma Dermoid & Epidermoid cyst Keratinising Cystic Odontogenic Tumour
  17. 17. Thyroglossal tract cyst Branchial cleft cyst Nasolabial Cyst Nasopalatine Canal Cyst
  18. 18. References • Philipsen HP, Reichart PA . The Development and Fate of Epithelial Residues after Completion of the Human Odontogenesis with Special Reference to the Origins of Epithelial Odontogenic Neoplasms, Hamartomas and Cysts. Oral Biosci Med. 2004; 1: 171-179. • Regezi JA, Sciubba JJ, Jordan RCK. Oral Pathology: Clinical Pathologic Correlations, 5th ed. St. Louis: Saunders; 2007. • Soames JV, Southam JC. 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 Munksgaard 2007. • Neville BW, Damm DD, White DH. Color Atlas of Clinical Oral Pathology 2nd ed. Ontario: BC Decker 2003.
  19. 19. Questionnaire Session

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