Odontogenic keratocyst with metaplastic epithelium: A case report.

Correct treatment begins with correct diagnosis. Arriving at a correct diagnosis require knowledge skill and art. Because many diseases have similar symptoms, the clinician must be astate in determining the correct diagnosis.[1] One lesion mimicking the other poses the diagnostic dilemma. Periapical lesions resulting from necrotic dental pulp are among the most common pathologic conditions within the alveolar bone.[2] Odontogenic cysts of the jaws include various pathological entities. Keratocystic odontogenic tumour (KCOT) is defined as "a benign uni- or multicystic, intraosseous tumour of odontogenic origin, with a characteristic lining of parakeratinized stratified squamous epithelium and potential for aggressive, infiltrative behaviour." In relation to OKC, there are two significant diagnostic issues. Firstly, they commonly show active epithelial growth which has prompted the belief that they should perhaps be regarded as neoplasm rather than a cyst. Secondly, they are known to occur in two fashions solitary (or sporadic) and as part of the BCNS.[3] The aggressive clinical behavior and frequent recurrence following curettage has been the focus of several studies, which indicated that the odontogenic keratocyst epithelial lining may have some intrinsic growth potential.[4] In light of the epithelial behavior here, we present a case of odontogenic keratocyst with metaplastic epithelium attributed to the presence of inflammation.

Introduction

Correct treatment begins with the correct diagnosis. Arriving at a correct diagnosis require knowledge, skill and art. One lesion mimicking the other poses a diagnostic dilemma.[1] Periapical lesions resulting from necrotic dental pulp are among the most common pathologic conditions within the alveolar bone.[2] Odontogenic cysts of the jaws include various pathological entities. By definition, these are the cysts (pathological cavities with fluid or semi-fluid contents but excluding pus) with an epithelial lining that derives from the tooth forming organ epithelia; the so-called glands of Serre, the rests of the Malassez and the reduced enamel epithelium. Some type of odontogenic cysts have characteristic epithelial linings and differ in their behavior.[3]

First described by Philipsen in 1956, odontogenic keratocyst (OKC) is now designated by the World Health Organization (WHO) as a keratocystic odontogenic tumour (KCOT) and is defined as “a benign uni- or multicystic, intraosseous tumour of odontogenic origin, with a characteristic lining of parakeratinized stratified squamous epithelium and potential for aggressive, infiltrative behaviour.” WHO “recommends the term keratocystic odontogenic tumour as it better reflects its neoplastic nature.”[5]

In relation to OKC, there are two significant diagnostic issues, firstly, they commonly show active epithelial growth which has prompted the belief that they should perhaps be regarded as neoplasm rather than a cyst. Secondly, they are known to occur in two fashions solitary (or sporadic) and as part of the BCNS.[3]

The aggressive clinical behavior and frequent recurrence following curettage has been the focus of several studies, which indicated that the OKC epithelial lining may have some intrinsic growth potential.[4] In light of the epithelial behavior here we present a case of odontogenic keratocyst with metaplastic epithelium attributed to the presence of inflammation.

Case Report

A 40-year-old male patient came to the department of oral medicine and radiology with a chief complaint of pain in the lower right back tooth region from 20 days. The pain was insidious in onset, pricking type, moderate in intensity and the pain aggravated following extraction of 47. On radiographic examination, a solitary multilocular radiolucency was seen in the right body of the mandible extending to angle and ramus measuring approximately 6 × 3 cms with scalloped outline and corticated margins. Excisional biopsy was done and sent for histopathological examination.

The soft tissue was routinely processed and stained with hematoxylin and eosin. The stained sections reveal the presence of epithelium lining and connective tissue wall. The epithelial lining was of uneven thickness of 5 to 8 cells exhibiting palisaded cuboidal to tall columnar basal cells in some areas shown in Figures 1 and 2 and thicker in other areas with rete ridge formation in few areas as shown in Figures 3 and 4. It was parakeratinized stratified with corrugated surface in few areas. Non-keratinized epithelium exhibits arcading patterns at places. Connective tissue wall was dense fibrous type consisting of dense chronic inflammatory infiltrate, irregular calcifications and numerous blood vessels and hemorrhagic areas. A diagnosis of odontogenic keratocyst was given correlating with radiographic features.

Figure 1

Photomicrograph (10×) showing parakeratinized stratified squamous epithelial lining and connective tissue wall with loss of typical palisaded basal cell layer and tombstone appearance

Figure 2

Photomicrograph (10×) showing keratinized stratified squamous epithelium with budding

Figure 3

Photomicrograph (10×) showing proliferated non-keratinized epithelium with chronic inflammatory infiltrate in the connective tissue wall

Figure 4

Photomicrograph (10×) showing arcading epithelium with chronic inflammatory infiltrate in the connective tissue

Discussion

OKC comprises approximately 11% of all cysts of the jaws. They occur most commonly in the mandible, especially in the posterior body and ramus regions.[6] Although OKC is classified as a developmental cyst, inflammation in the connective tissue wall of OKC has been found in almost 75% of the cases reported in the literature. In the present case, there was dense inflammation in the cystic wall.[4]

Unlike epithelial cells of an odontogenic keratocyst, which is a neoplastic lesion, the basal cells of an inflammatory apical cyst are not capable of self-proliferation without stimulation by external signals such as inflammatory mediators, proinflammatory cytokines, and growth factors released by innate and adaptive immune cells during apical periodontitis.[1]

Growth of odontogenic keratocyst is chiefly in the anteroposterior dimension and the lesions may attain remarkable size without significantly deforming the jaw skeleton which is evident in the present case. The particular tendency to rapid growth is due to higher activity of the epithelial cells of the cyst lining stimulating osteolytic activity of prostaglandin substances in the cell population of the cyst lining and higher accumulation of hyperkeratotic scales in the lumen of the cyst with resulting greater difference in hydrostatic pressure.[7]

Odontogenic keratocysts are lined by ortho or parakeratinised epithelium exhibiting corrugated surface and a basal layer of palisaded tall columnar cells. In the present, there are features of both radicular cyst and odontogenic keratocyst. The clinical history was negative for carious tooth and replacement of the classic parakeratinized lining of OKC with non-keratinizing squamous epithelium has been reported in cases with inflammation present in the cyst wall, and in cases following decompression treatment where inflammation is always present.

In a study done to assess the correlation of epithelial cell proliferation and inflammation in OKC metaplastic squamous epithelium was found in 64% of all cases, twice as frequent in cases with high inflammatory scores (90%) than in cases with low scores (44%).[4]

Conclusion

MacDonald and Fletcher found that cytokeratin expression in metaplastic epithelium attributed to the presence of inflammation was focally altered by inflammation. The morphologic alterations in the epithelial lining of metaplastic epithelium attributed to the presence of inflammation may also be associated with changes in the proliferative potential, thus affecting its biologic behavior.[4]

In the present case, the presence of severe inflammation has attributed to the metaplastic change in the epithelium from keratinized to non-keratinized. Proper histopathologic diagnosis is essential for the proper management of the case which affects the betterment of the patient health.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.