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 .