L. Su et al., DISTINGUISHING FEATURES OF FOCAL CEMENTO-OSSEOUS DYSPLASIAS AND CEMENTO-OSSIFYING FIBROMAS .1. A PATHOLOGICAL SPECTRUM OF 316 CASES, Oral surgery, oral medicine, oral pathology, oral radiology and endodontics, 84(3), 1997, pp. 301-309
Focally expressed cemento-osseous dysplasia (periapical cemento-osseou
s dysplasia and focal cemento-osseous dysplasia) and cemento-ossifying
fibroma (ossifying fibroma and cementifying fibroma) are two clinical
ly recognized entities that are not easily differentiated histopatholo
gically because of the lack of recognition of specific microscopic fea
tures. We have assessed 20 pathologic parameters for their ability to
distinguish reliably between the two. Included in this study were 241
cases of focally expressed cemento-osseous dysplasia and 75 cases of c
emento-osseous fibroma diagnosed from a combination of clinical, radio
graphic, and histopathologic information. Results revealed that 92.5%
of focally expressed cemento-osseous dysplasia were composed of multip
le small fragments of tissue whereas 88.0% of cemento-osseous fibromas
showed a large intact specimen. Thick curvilinear trabeculae (''ginge
r root'' pattern) or irregularly shaped cementum-like masses were typi
cally seen in focally expressed cemento-osseous dysplasia, whereas thi
n isolated trabeculae with prominent osteoblastic rimming were more co
mmonly observed in cemento-osseous fibroma. The stroma of focally expr
essed cemento-osseous dysplasia often displayed characteristic caverno
us-like vascularity that was almost always associated with bony trabec
ulae. Free hemorrhage was frequently interspersed in the artifactual s
paces throughout focally expressed cemento-osseous dysplasia. In contr
ast, the cases of cemento-osseous fibroma showed more cellularity in t
he stroma in which a storiform pattern was present in more than hall t
he lesions studied. Giant cells, when present in cemento-osseous fibro
ma, were clustered in the center of the cellular stroma. The features
described here allowed distinction histopathologically in 94% of cases
studied. Three progressive stages of focally expressed cemento-osseou
s dysplasia and subtypes oi cemento-osseous fibroma may be recognizabl
e microscopically.