A CLINICOPATHOLOGIC STUDY OF ODONTOGENIC (OKC) AND THE ROLE OF AgNORs IN CELL PROLIFERATION

* Vindhya Savithri **Sudha S ***Shameena P.M ****Ipe Varghese

Abstract :

The histologic pattern of OKC is distinct and hence the has potential for more aggressive behaviour than other of the jaws. When inflammation is present within the cyst wall of an OKC, the character of the cyst lining changes from the classical pattern to a non-keratinized stratified squamous lining typical of other inflammatory cysts. This transformation often occurred quite abruptly at the margin of inflammed and non- inflammed tissue. These findings prompted us to investigate the association of inflammation with OKC lining changes and explore its possible relationship to clinical behaviour.

Introduction : OKC occurs over a wide age range with a (OKC) is a peak in the second and third decades. It clinicopathologically distinct form of has a marked male predilection. OKC is developmental . It is seen predominantly in the molar and known for its pathognomonic ramus of mandible. Small OKCs may be microscopic features, aggressiveness and asymptomatic while larger ones may be high recurrence rate. The term ‘OKC’ was associated with pain, swelling and pus introduced by Philipsen in 1956 . It discharge. It is associated with naevoid represents 10% to 12% of odontogenic basal cell carcinoma syndrome – Gorlin developmental cysts (Eslami B et al Goltz sydrome. Radiographically, it 200311). usually has well defined radio lucency with

Oral & Maxillofacial Pathology Journal [ OMPJ ] Vol 1 No 1 Jan- Jun 2010 ISSN 0976-1225 distinct sclerotic margin. They may be behaviour which reflects this unilocular or multilocular and may transformation. envelop an unerupted tooth. AgNORs : Nucleolar organizer regions (NORs) are The histologic features are distinct, the loops of DNA that transcribe genes for cyst is lined by orthokeratinised or ribosomal RNA. AgNORs are NOR parakeratinised stratified squamous associated acidic protein selectively epithelium which is 4 – 8 cell layers thick, stained by silver methods. They vary in with corrugated surface . Absence of rete size and shape according to nucleolar pegs is a characteristic feature. The transcription and are intimately related to columnar or cuboidal basal cells have . The amount of AgNORs polarized and palisaded nucleus. The proteins is proportional to proliferative epithelial lining is weakly attached to activity of the cell (Egan MJ et al 199210). fibrous wall and may easily separate. The presence of satellite cysts and odontogenic epithelial islands in the cyst wall is another Aims and Objectives : feature. 1. To assess the clinical and Effect of inflammation : pathological features of OKC. Rodu B et al (198717) reported that the 2. To compare the clinical and cyst lining changes from classical pattern pathological characteristics of to a non – keratinized stratified squamous inflamed OKCs with the non- lining typical of other inflammatory cysts. inflamed ones. The transformation occurred abruptly at 3. To determine the proliferative the margin of inflamed and non-inflamed capacity of the basal and parabasal tissue. The epithelial lining of OKC is layers of both inflamed and non- more active than other odontogenic cysts inflamed OKC lining by counting and hence has an important role in its AgNORs. aggressive behaviour and high recurrence 4. To compare the AgNOR counts rate. The change in epithelial lining in the in inflamed and non-inflamed presence of inflammation may be OKC. accompanied by re-alignment in biologic

Oral & Maxillofacial Pathology Journal [ OMPJ ] Vol 1 No 1 Jan- Jun 2010 ISSN 0976-1225

Materials and Methods : distilled water for one minute, dehydrated, cleared and mounted in DPX. The study comprised of 30 cases of AgNOR sites were seen as intranuclear histologically proven OKC. The clinical black dots and the background as pale details were noted retrospectively from yellow. The AgNOR’s were enumerated the files.Two sections were cut from the using a x100 oil immersion lens. The paraffin blocks of the cases.Haematoxylin AgNOR counts in 100 cells were made in and Eosin staining was done and sections the basal and parabasal layers of the were examined for the histopathologic epithelium and the results expressed as the features and divided into two groups mean number of NORs per nucleus. namely inflamed and non-inflamed depending upon the presence or absence of inflammatory infiltrates in the cyst wall. Observations and Results : Another section was cut from the blocks of inflamed OKCs for silver staining. This It was noted that OKCs occurred over a was done by silver nitrate method (Ploton wide age range and the peak prevalence et al2). The working solution was was seen in the 2nd and 3rd decades for prepared as follows: both inflamed and non-inflamed ones. Males have a marked predilection in both 50% Silver nitrate solution – 2 types. Both inflamed and non-inflammed parts occur more in the mandible than the Gelatin Solution (Gelatin 2g, maxilla. The clinical presentations Formic acid 1ml, Distilled included swelling, pain and pus discharge. water 100ml) – 1 part Majority of both types had unilocular radiolucency. 43 % of cysts had associated The two solutions were mixed unerupted teeth and 20% cases had immediately before use. The dewaxed multiple cysts of which an equal number sections were hydrated and rinsed in were inflamed and non-inflamed. 16.60% distilled water. The slides were then cases reported of previous cyst incubated in freshly prepared working enucleation and all the cases were of non- solution for 45 minutes at room inlfamed type. The histologic features temperature, followed by rinsing in were studied under three broad groups

Oral & Maxillofacial Pathology Journal [ OMPJ ] Vol 1 No 1 Jan- Jun 2010 ISSN 0976-1225 namely; the epithelium, epithelial cyst occurring in inflamed OKCs when connective tissue interface and the compared to the non-inflamed ones. connective tissue. 90% of cases (equal AgNOR counts may be useful as a number of both) showed parakeratinized proliferative marker to differentiate epithelium. Interestingly, varying thickness between inflamed and non-inflamed of epithelium was found in 23.30 % of the OKCs. case and all of them were of inflamed Reference: type. In these cases, rete peg formation 1. Ahlfors E, Larsson A, Sjogren S. The was also noted. The cells in the basal layer Odontogenic Keratocyst: A Benign cystic was cuboidal in 53.30 % of cases . tumor? J Oral Maxillofac Surg 1984; 42: Majority of the cysts ( 63.30%) had the 10-19. typical corrugated surface. Detachment of 2. Bancroft J.D, Gamble M. Theory and the epithelium from the connective tissue Practice of histological techniques. 5th ed. was seen in 86.60 % cases. Satellite cysts, 3. Brannon R.B. The Odontogenic Keratocyst. Islands of odontogenic epithelium were A clinico pathologic study of 312 cases part found in more number in inflamed I. Clinical features Oral Surg; 1976: 42 OKCs. The AgNOR counts in the (1): 54-72. inflamed OKCs were significantly higher 4. Brannon R.B. The Odontogenic keratocyst. compared to the non-inflamed group. A clinicopathologic study of 312 cases. Part II. Histologic features Oral Surg 1977; Summary and Conclusion : 43(2): 233-255. 5. Browne R.M. The Odontogenic Keratocyst. A statistically significant association was Clinical Aspects. Brit. Dent. J, 1970: 225- found between the presence of 231. inflammation in the cyst wall and increase 6. Browne R.M. The Odontogenic keratocyst. in thickness of the lining, rete peg Histological features and their correlation formation and presence of odontogenic with clinical behaviour. Brit dent J. 1971; epithelial islands. The AgNOR counts 131: 249-259. were statistically significant in the 7. Coleman H.G, Altini M, Groeneveld H.T. inflamed OKCs as compared to non- Nucleolar organizer regions (AgNORs) in inflamed OKCs. This study implicates odontogenic cysts and . J that there is a greater chance of recurrent Oral Pathol Med 1996; 25: 436-40.

Oral & Maxillofacial Pathology Journal [ OMPJ ] Vol 1 No 1 Jan- Jun 2010 ISSN 0976-1225

8. Crowley T.E, Kaugars G.E, Gunsolley J.C. 15. Magnusson B.C. Odontogenic : a Odontogenic keratocysts: A clinical and clinical and histological study with special histologic comparison of the parakeratin and reference to enzyme histochemistry. J Oral orthokeratin variants. J Oral Maxillofac Pathol 1978;7:8-18. Surg 1992; 50: 22-26. 16. Murtadi A.E, Grehan D, Toner M, 9. de Paula A.M.B, Carvalhais J.N, McCartan B.E. Proliferating cell nuclear Domingues M.G, Barreto D.C, Mesquita antigen staining in syndrome and R.A. Cell proliferation markers in the nonsyndrome odontogenic keratocysts. Oral odontogenic keratocyst: effect of inflammation Surg Oral Med Oral Pathol Oral Radiol J Oral Pathol Med 2000: 29: 477-82. Endod 1996; 81: 217-20. 10. do Carmo M.A.V, Silva E.C: 17. Neville B.W, Damm D.D, Brock T. Argyrophilic nucleolar organizer regions Odontogenic keratocysts of the Midline (AgNORs) in ameloblastomas and maxillary region. J Oral Maxillofac. Surg adenomatoid odontogenic tumours (AOTs). 1997; 55: 340-344. J Oral Pathol Med 1998; 27: 153-6. 18. Rodu B, Tate A.L, Martinez Jr. M.G. 11. Egan M.J, Crocker J. Nucleolar organiser The implications of inflammation in regions in pathology. Br J Cancer 1992; 65: odontogenic keratocysts. J Oral Pathol 1987; 1-7. 16: 518-521. 12. Eslami B, Yaghmaei M, Firoozi M, Saffar 19. Scharffetter K, Balz-Herrmann C, Lagrange A.S. Nucleolar organizer regions in selected W, Koberg W, Mittermayer C. odontogenic lesion. Oral Surg Oral Med Proliferation Kinetics – Study of the Growth Oral Pathol Oral Radiol Endod 2003; 95: of Keratocysts. J Cranio-Max. Fac, Surg. 187-92. 1989; 17:226-233. 13. High A.S, Quirke P, Hume W.J. DNA- 20. Shear M. Developmental odontogenic cysts. ploidy studies in a keratocyst undergoing An update. J Oral Pathol Med 1994: 23: subsequent malignant transformation. J 1-11. Oral Pathol 1987; 16: 135-1 38. 21. Woolgar J.A, Rippin J.W, Browne R.M. 14. Leek R.D, Alison M.R, Sarraf C.E. A comparative study of the clinical and Variations in the occurrence of silver-staining histological features of recurrent and non- nucleolar organizer regions (AgNORs) in recurrent odontogenic keratocysts. J Oral non-proliferating and proliferating tissues. J Pathol 1987; 124-128. Path 1991; 165: 43-51.

Oral & Maxillofacial Pathology Journal [ OMPJ ] Vol 1 No 1 Jan- Jun 2010 ISSN 0976-1225

Changes in OKC Epithelium due to inflammation. (H&E, 10X) Silver stained section showing rete peg

formation & satellite cysts (10X)

* Reader, Annoor Dental College, Muvattupuzha, Ernakulam District. ** Associate Professor, Department of Oral Pathology, GDC, Calicut. *** Professor and Head, Department of Oral Pathology, GDC, Calicut. **** Principal, Government Dental College, Calicut.

Oral & Maxillofacial Pathology Journal [ OMPJ ] Vol 1 No 1 Jan- Jun 2010 ISSN 0976-1225