The most striking microscopic feature of this tumour are the
so-called "Ghost" epithelial cells present either in the
epithelial lining or connective tissue.
Ghost cells are large pale
anucleate cells with homogeneous pale eosinophilic cytoplasm and
very pale to clear central areas instead of a basophilic nucleus.
Individual ghost cells may fuse
together to form large sheets of amorphous eosinophilic structure on
which calcification may occur.
Confocal laser scanning microscopy
observations have disclosed that Calcifying odontogenic cyst
ghost cells autofluoresce. However, autofluorescence intensities are
variable, possibly due to hard keratin presence .
Anucleated ghost cells have been
referred to in the English literature using a variety of terms,
including "degenerated epithelium" , "epithelial pearls" , "enamel
organ" , "concentric homogenous bodies" , "calcified globules
resembling keratin" , "hyaline-like bodies" , and "keratinized
squamae", to name a few.
In the German literature, Rywkind and
Shiltzow introduced the name "rote Zellen" (red cells) for ghost
cells in 1931.
Dr RJ Gorlin
et al, was the first person to
describe calcifying ghost cell odontogenic cyst (CGCOC) under the
term calcifying odontogenic cyst (COC)
Although Gorlin et al. coined the
term "calcifying odontogenic cyst" (COC) in 1962, this type of cyst
was initially reported three decades earlier by Dr AW Rywkind in
Russia, and almost concurrently by Dr JC Bloodgood in the United
States and Dr S Sato in Japan.
The term "calcifying epithelioma of Malherbe" first appeared in a
1931 French report.
Highman and Ogden (1944)
first described ghost cell in pilomatrixomas. They described ghost
cells as dyskeratotic cells, which are similar to viable cells, but
have a distinct outline.
According to some authors the term
"ghost cells" had its origin in two American seminal articles by
Thoma and Goldman in 1946.
As the number of cases increased,
Gorlin et al. began to call calcifying odontogenic cyst as "oral
Malherbe" by the 1950s.
Dr L Gold also reported on COC
in 1963. Dr RJ Gorlin's study stressed the histological resemblance
of COC to cutaneous calcifying epithelioma of Malherbe and Dr L Gold
focused on the relationship between COC and calcifying epithelial
consideration of Dr Gold’s suggestion , Dr Gorlin in 1968 also used
a similar compound name "calcifying and keratinizing odontogenic
cyst" only once.
Although Thoma in 1946 came to the
conclusion that ghost cell keratinization is caused by necrobiosis
of the odontogenic epithelium preceding calcification, there is no
mention of ghost cells in the 3rd (1950), 4th (1954) , or 5th (1960)
editions of his textbooks.
This fascinating tumour has been reported under a variety of other
names including keratinizing cyst ; keratinizing cyst and
calcifying odontogenic cyst (KCOC) ; calcifying ghost cell
odontogenic tumor; dentinogenic ghost cell odontogenic tumour ;
epithelial odontogenic ghost cell tumour; ghost cell cyst ;
calcifying ghost cell odontogenic tumour, and dentino-ameloblastoma
by various authors.
From the year of description,
disagreements exist regarding the nature, terminology and
classification of CGCOC.
These controversies and confusion
about the lesion are due to existence of two variants of the lesion:
cystic and the neoplastic forms.
In 1971, the WHO described CGOC as
a "non-neoplastic" cystic lesion; nevertheless, it decided that the
lesion should be classified as a benign odontogenic tumour.
In 1992, the World Health Organization
(WHO) classified CGOC as a neoplasm rather than a cyst but confirmed
most of the cases are nonneoplastic.
The unified term "odontogenic
ghost cell lesions (OGCL)" or "ghost cell odontogenic tumors",
which refers to the origin and nature of these lesions and also
defines their most characteristic microscopic feature, was proposed
under the 2005 WHO guidelines.
World Health Organization (2005)
updated its classification of odontogenic tumors , and reclassified
the calcifying odontogenic cyst subdividing it into three distinct
- calcifying cystic odontogenic
- dentinogenic ghost cell tumor (DGCT)
- ghost cell odontogenic carcinoma
Calcifying ghost cell odontogenic cyst
is a very rare tumour. Average oral and maxillofacial surgeon is
likely to see only one case or two during his/her professional
In Asians, it showed a higher
incidence in younger age group; almost 70% occurred in the second
and third decades, whereas in Caucasians, this tumour was reported
in only about 53% of patients in this age group.
In the Asians, the lesions showed a
predilection for the maxilla (65%), whereas in Caucasians, the
mandible (62%) was more commonly involved. The most common site of
occurrence has been the anterior part of the jaws. In the mandible,
several cases have crossed the midline, but this is not a prominent
feature in the maxilla
Although characteristic of calcifying
cystic odontogenic tumors , "Ghost cells" are also found in other
odontogenic lesions namely ameloblastoma odontoma and
ameloblastic fibro-odontoma , and in nonodontogenic tumours such as
pilomatrixoma and craniopharyngioma.
The World Health Organization
Classification of Head and Neck Tumours considered ghost cells as
transitory squamous cells at various stages of development. However
to date the true nature of these ghost cells is not known. The
calcifying process of ghost cells also remains ill-understood.