Squamous cell carcinoma arising in dermoid cyst or cystic teratoma of ovary occurs
rarely in women; its incidence is low and varies from 1.7% to 3%.
A non-teratomatous squamous cell carcinoma of ovary is even rarer. Only one or two
authentic cases are reported in the literature.
Human ovarian squamous cell carcinoma is usually found in benign cystic teratomas
which undergo malignant transformation. According to E. R. Novak, histogenesis of
teratoma is inadequately established and their relationship to other tumors such as
struma ovarii, seromucinous cystadenomata, dysgerminoma and embryonal carcinoma is
not clear. Black and Benitez reported a most unusual case of nonteratomatous squamous
cell carcinoma in situ of ovary in a 35-year-old woman of Mongolian descent, who was
operated on for a large cystic ovary measuring 8.2×6.3×3.4 cm. Three cysts were
found on section; one of them was lined by squamous cell carcinoma in situ, and the
remaining two were lined by flattened cuboidal epithelium. This certainly indicates that
squamous cell carcinoma may haute a non-teratomatous origin in ovary. Black and
Benitez suggested that perhaps an atypical squamous metaplasia of the endocervical like
epithelium of an ovarian cyst could conceivably progress to an in situ carcinoma.
Another case of a primary cystic squamous cell carcinoma was reported to have
originated in the areas of squamous metaplasia in a mucinous cystadenoma. Therefore it
is quite possible that the Black's case may well be of the same histogenesis as the
case cited above, although in this case the original cyst may have been lined by
follicular cells and the latter undergone squamous metaplasia progressing to carcinoma.
Since there is a growing evidence in recent years that granulosa cells are mobile as
well as derived from the ovarian stroma, it is conceivable that many hormone-producing
tumors of ovary also take their origin in the stroma, which is, as R.A. Willis puts it
and others concur, not a mere supportive tissue but an undifferentiated blastema that is
highly plastic and capable of wide range of metaplastic transformation. Some form of
malignant Brenner tumors look very much like primary squamous cell carcinoma of
ovary and Shay and Janovski suggested to classify the tumor as epidermoid,
adenocarcino matous and mixed type.
There are numerous studies and reports on histogenesis and hormonal activity of
granulosatheca cell tumor, Brenner tumor, and serous cystadenocarcinoma. Review Of
the literature makes us believe more strongly that all these tumors, be .it feminizing or
musculinizing, are closely related to each other and of the same stromal origin. The
current report of an experimental study of mouse ovarian cell cultures and tumors
which they induced is presented to support the view that many of these tumors are
akin to one another and of common origin in bipotential ovarian cells.
The ovarian epithelial and stromal cells were shown to undergo an interchangeable
type of differentiation. Knowledge of the conditions under which this ability becomes
manifested and of the mechanisms in altering cell differentiation may lead to a better
understanding of histogenesis of ovarian tumors, including origin of such unusual type
of ovrarian neoplasm as squamous cell carcinoma.
An in vitro method of growing epithelial cell cultures isolated from explanted ovary of
mouse led to the development of cell lines with tumorigenic properties. Among various
neoplasms such as granulosa cell carcinoma and sarcomatoid tumors produced by
inoculation of isologous mice, a squamous cell carcinoma was also observed.
The description of the method by which this unusual tumor was unexpectedly
produced and the demonstration of the usefulness of an in vitro analytical approach to
studies of differentiation of various types of ovarian cells and of histogenesis of ovarian
tumors are the main objectives of this report.
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