the calcifying odontogenic cyst ( coc ) is an uncommon odontogenic lesion , which was described by gorlin et al . in 1962 as a distinct entity .
since then , literature shows a large controversy regarding terminology and classification in spite of the currently acceptation of gorlin 's original designation by the world health organization ( who ) in 1971 .
coc is thought to represent a non - neoplastic lesion , but it has a potential for continuous growth .
a lot of confusion and disagreement is present in the terminology and classification of coc .
some investigators have considered coc as a tumor with a tendency for marked cyst formation .
this concept , called  monistic  by toida has led some researchers to substitute the terms  calcifying ghost cell odontogenic tumor  or 
approach has been suggested that coc can contain two entities : 
 cyst : calcifying ghost cell odontogenic cystneoplasm ( benign : calcifying ghost cell odontogenic tumor ; or malignant : malignant calcifying ghost cell odontogenic tumor ) ; and combined lesion : each of the categories described above associated with odontoma , ameloblastoma , or other odontogenic lesions . 
 
cyst : calcifying ghost cell odontogenic cyst neoplasm ( benign : calcifying ghost cell odontogenic tumor ; or malignant : malignant calcifying ghost cell odontogenic tumor ) ; and combined lesion : each of the categories described above associated with odontoma , ameloblastoma , or other odontogenic lesions . the calcifying cystic odontogenic tumor ( ccot ) represents less than 2% of all odontogenic tumors and cysts .
the intraosseous ccot ( iccot ) is an unilocular or multilocular destructive radiolucent lesion that may contain irregular calcifications .
ccot is usually an asymptomatic slow growing swelling of the jaws or gingival tissues , depending upon whether the lesion is intra or extraosseous .
it has been reported to be found between the 1 and 9 decades of life , with a highest incidence occurring in the 6 - 7 decades and tends to appear with equal frequency amongst males and females .
clinically it appears as a localized or pedunculated gingival mass with no distinctive features and radio graphically it shows no or only superficial bone involvement with surface erosion .
the histological features of eccot are similar to the iccot characteristics , and include an epithelial lining of varied thickness , composed of a distinct columnar ( and occasionally cuboidal ) basal layer , with cells that contain darkly staining nuclei , polarized away from the basement membrane and palisading , similar to the ameloblasts . within the epithelial lining
, there is an irregular collection of cells , including sheets of stellate reticulum and eosinophilic cells so called ghost cells .
next to the basal layer , irregular or dysplastic dentin and osteoid can also be found .
the present paper reports a case of an eccot in a 17-year - old male with the brief review of relevant literature .
a 17-year - old male patient reported with a chief complaint of swelling in relation to the right region of the lower jaw , since 4 months .
on intra - oral examination , a pinkish dome - shaped , oval nodular growth was seen measuring about 1  1 cm in diameter , in relation to 48 region .
the overlying mucosa was normal with superficial blood vessels , giving a pinkish appearance [ figure 1 ] .
intra - oral periapical radiograph ( iopa ) shows no osseous involvement , but vertically impacted 48 [ figure 2 ] .
based on these features a differential diagnosis of hyperplastic or reactive lesions arising from the gingival and eruption cyst was made .
clinical appearance of the growth radiograph intra - oral periapical radiograph in relation to 48 excisional biopsy under local anesthesia was performed .
microscopic examination showed a cyst lined by an epithelium with numerous ghost cells and few calcified masses .
the basal cells were cuboidal to columnar with darkly staining nuclei , polarized away from the basement membrane , and showed palisading appearance similar to ameloblasts [ figure 3 ] .
basal cells are cuboidal to columnar in shape showing hyperchromatism , few showing reverse polarity with palisading appearance ( h and e , 10 )
coc or gorlin cyst was described first by gorlin and pretarious as a definite pathologic entity .
a rare developmental odontogenic lesion ( less than 2% of jaw cysts ) is described as having features of both cystic and solid neoplasm .
the latest who classification 2005 of odontogenic tumors [ table 1 ] renamed the cystic type of this entity as ccot with four subtypes .
world health organization calcification ( 2005 ) of calcifying cystic odontogenic tumor and dentinogenic ghost cell tumor the term dentinogenic ghost cell tumor was retained for neoplastic type .
most cases of ccot arise centrally from within the bone , but occasionally they may occur peripherally .
eccot has been reported to be found between the 1 and 9 decades of life , with a highest incidence occurring in the 6 - 7 decades , and tends to appear with equal frequency amongst males and females .
it is usually present as a slowly enlarging asymptomatic mass with smooth surface in the gingiva or alveolar mucosa .
the clinical differential diagnosis of eccot includes common gingival growths of non - neoplastic nature and other peripheral odontogenic tumors .
the most common locations included the incisor - cuspid and the premolar regions , with only a few lesions located in the molar - retromolar region .
the size of the lesion ranged from 0.5 to 4 cm in greatest diameter and the majority of cases were less than 1.5 cm .
clinically , a variety of diagnosis are made by clinicians , the most common being the fibroma or fibrous hyperplasia .
other differential diagnoses are gingival cyst of adult and peripheral ameloblastoma . however , currently the origin of eccot is not known but regarding to the histogenesis of eccot two major sources of origin may be considered .
the lesion which are located entirely within connective tissue of gingiva and separated from the surface epithelium by a band of connective tissue ( just like present case ) probably arise from remnants of the dental lamina whereas other lesions appear arising from the surface epithelium .
radio graphically , it has been reported that eccot appears as a radiolucent area with scattered amounts of calcification .
microscopically four variants of eccot like ccot were distinguished : 
 type 1 ( simple cystic),type 2 ( odontoma associated),type 3 ( ameloblastomatous proliferating),type 4 ( eccot associated with benign odontogenic tumors other than odontoma ) . 
 
type 1 ( simple cystic ) , type 2 ( odontoma associated ) , type 3 ( ameloblastomatous proliferating ) , type 4 ( eccot associated with benign odontogenic tumors other than odontoma ) .
type 1 is the most common pattern characterized by cystic epithelial lining in which a well - defined basal layer of columnar cells and overlying layers resemble stellate reticulum of enamel organ with masses of ghost cells , which may be located within the epithelial lining or fibrous capsule .
the presence of ghost cells in ccot is not pathognomonic , having been described in ameloblastoma , ameloblastic fibroma , ameloblastic fibro - odontoma , and odontomas .
sometimes variable quantities of dentinoid material are laid down adjacent to epithelial lining . in some instances ,
the microscopic differential diagnosis , especially type 1 and 3 must be made with peripheral ameloblastoma .
both lesions share the presence of prominent elongated basal cells and stellate reticulum zone , but the presence of ghost cells is rare in ameloblastoma .
eccot has a less aggressive behavior than the intraosseous counterpart and a simple excision biopsy is curative .
follow - up treatment ranged from 9 months to 60 months , only one case of recurrence could be observed . in summary ,
the current paper presents a case of eccot ( type 1 ) in an 17-year - old male patient , located in the posterior alveolar mucosa in relation to 48 region , measuring about 1  1 cm in diameter .
it should be included by the general dentists in the differential diagnosis of other oral hyperplastic / reactive lesions or cystic lesion arising from the gingiva or alveolar mucosa due to its clinical similarities .
more data are needed to draw conclusion relative to any differences in their nature and behavior .
 odontogenic cysts comprise a diverse group of exceptional lesions derived from epithelial elements of the tooth - forming apparatus . calcifying 
 cystic odontogenic tumor is a rare odontogenic lesion , which represents about 2% of all odontogenic tumors and cysts . 
 it may occur in a central ( intraosseous ) or peripheral ( extraosseous calcifying cystic odontogenic tumor [ eccot ] ) location . 
 eccot in contrast to central , tends to affect the older patients , commonly located in the anterior lower jaw , is less aggressive and the recurrence is rare . here , we report clinico - pathological and radiographic features of eccot located in relation to 48 ( posterior lower jaw ) measuring about 1 cm in the greatest diameter in a 17-year - old male . 
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