CYSTS OF THE PAROVARIUM.
The parovarium consists of a series of fine tubules lying between the
layers of the mesosalpinx. It may be seen in the fresh specimen by
holding the mesosalpinx stretched between the eye and the light (Fig.
145).
The typical parovarium consists of three parts: a series of vertical
tubules; a series of outer tubules free at one extremity; and a larger
longitudinal tubule.
The vertical tubules range from five to twenty-four in number. They
converge somewhat toward the ovary, where they end in blind extremities
and become closely associated with the paroöphoron. At the other end
they terminate in the larger longitudinal tubule.
The series of outer tubules are called Kobelt’s tubes. They are free
and closed at the distal extremity, while at the proximal extremity
they join the longitudinal tubule. The larger longitudinal tubule is
called the duct of Gärtner. It may sometimes be traced traversing the
broad ligament to the uterus, and through the walls of this organ and
of the vagina to its termination at the urethra. It corresponds to the
vas deferens in the male. When persistent in the vaginal wall it may
become the starting-point of a vaginal cyst.
The vertical tubes of the parovarium are from 0.3 to 0.5 millimeters
in diameter. They are occasionally found lined with ciliated columnar
epithelium. Usually they contain a granular detritus representing the
remains of broken-down epithelium.
Cysts may arise from any of the parts of the parovarium.
Kobelt’s tubes frequently become distended, and form small
pedunculated cysts about the size of a pea. They are of no clinical
importance (Fig. 145). They are often observed in operations for
ovarian disease, and are very often mistaken for the hydatid or the
cyst of Morgagni which springs from the Fallopian tube, and which has
already been described.
[Illustration: FIG. 170.--Cyst of the parovarium. There is no
distortion of the ovary. The Fallopian tube has been much elongated.]
The difference between these two varieties of small cysts may be
determined by careful examination of the point of origin and by
means of the microscope. Sutton states that the cyst of Morgagni has
muscular walls and is lined by ciliated columnar epithelium. In the
cyst of Kobelt’s tubes the walls are fibrous and the lining is cubical
epithelium.
Large cysts of the parovarium originate from the vertical or the
longitudinal tubules, and usually remain sessile and develop between
the layers of the mesosalpinx and the broad ligament. As the cyst
grows and separates the layers of the mesosalpinx, it comes into close
relationship with the Fallopian tube. This structure, being held by its
uterine connection and the tubo-ovarian ligament, becomes stretched
across the surface of the cyst and very much elongated. The elongation
of the Fallopian tube is a very constant accompaniment of parovarian
cysts. The tube may attain a length of 15 or 20 inches. The fimbriæ may
also become much stretched and elongated by the traction of the growing
cyst, and may attain a length of 4 inches.
The ovary is unaffected unless the cyst be of very large size, in which
case the ovary may be stretched upon the surface of the cyst, so that
its position becomes difficult to determine.
There are two varieties of parovarian cyst--the simple and the
papillomatous.
The _simple parovarian cyst_ has a very thin wall of uniform thickness.
In small cysts, less than the size of a child’s head, the wall may
be transparent. It is of a light yellowish or greenish color, and
the fine vessels ramifying upon the surface are plainly visible. As
one would expect from the direction of growth, the outer covering
of the cyst is peritoneum, which is not adherent and may be readily
stripped off. The middle coat is composed of fibrous tissue containing
unstriped muscle. The lining membrane is ciliated columnar epithelium,
stratified epithelium, or simple fibrous tissue, according to the size
of the cyst. The changes in the character of the epithelium are due to
pressure. The cyst-contents are a clear, limpid, opalescent fluid of a
specific gravity below 1010.
In the _papillomatous parovarian cyst_ the interior is covered with
warts or papillomatous growths resembling in every respect those
that occur in the cyst of the paroöphoron, already described. The
papillomatous parovarian cyst exhibits the same clinical features,
and is liable to the same accidents, as the paroöphoritic cyst. It may
become perforated and infect the general peritoneum.
The walls of the papillomatous parovarian cyst are somewhat thicker
than those of the simple parovarian cyst; the fluid contents are not so
clear and limpid, and may contain altered blood that has escaped from
the papillomata.
Parovarian cysts are almost invariably unilocular. Only a few cases
have been reported in which two or more cavities were present.
The cysts are of small size, not often exceeding that of a child’s
head. They may, however, attain large dimensions and contain several
quarts of fluid.
Parovarian cysts are of very slow growth, and refill but slowly after
tapping or rupture. On account of the thinness of the cyst-walls,
these cysts seem especially liable to the accident of rupture. Unless
the cyst be papillomatous, the bland, unirritating fluid is readily
absorbed by the peritoneum, and the cyst may remain quiescent for a
long period.
Cysts of the parovarium occur most frequently during the period of
active sexual life. Unlike dermoids and cysts of the oöphoron, they are
unknown in childhood.
Cysts of the parovarium are much less common than cysts of the oöphoron
and paroöphoron. In 284 tumors of the ovary and parovarium operated
upon by Olshausen, about 11 per cent. originated in the parovarium.
Some authorities maintain that in rare instances dermoid cysts may
arise from the parovarium.
The symptoms of parovarian cysts resemble those of ovarian cysts of
similar development. On account of the intra-ligamentous development
of the tumor, pressure-symptoms may appear early. The cyst is of such
slow growth that the simple parovarian cyst may exist for a long time
without giving any trouble whatever. The slow growth is the only
clinical feature that would enable one to make a diagnosis between
parovarian and ovarian cyst.
COMPARISON OF OÖPHORITIC, PAROÖPHORITIC, AND PAROVARIAN CYSTS.
The chief characteristic features of the large cysts of the ovary and
the parovarium--the glandular cyst, the paroöphoritic cyst, and the
parovarian cyst--may be tabulated for comparison as follows:
[Illustration: FIG. 171.--Section, perpendicular to the long axis of
the Fallopian tube, passing through the tube, the parovarium, and the
ovary; showing the relation of the structures to the peritoneum of the
broad ligament.]
[Illustration: FIG. 172.--Section, perpendicular to the long axis of
the Fallopian tube, showing the relation of an oöphoritic cyst to the
peritoneum of the broad ligament.]
[Illustration: FIG. 173.--Section, perpendicular to the long axis of
the Fallopian tube, showing the relation of a paroöphoritic cyst to the
oöphoron and the peritoneum of the broad ligament.]
=Glandular Oöphoritic Cyst.=--Intra-peritoneal in development; no
peritoneal investment. Ovary destroyed early in the course of the
disease. Cyst multilocular.
Fluid contents thick, colored; specific gravity greater than 1010.
Tumor of rapid growth.
Usually unilateral.
Fallopian tube distinct from tumor, and not much, if any, elongated.
=Paroöphoritic Cyst.=--Often extra-peritoneal in development, in which
case there is a detachable peritoneal investment.
Oöphoron not at first involved by the growth.
Unilocular.
Fluid contents less thick and viscid than in oöphoritic cyst.
Interior filled with papillomata.
Tumor usually of slower growth than the oöphoritic cyst.
Very often bilateral.
Fallopian tube more likely to be involved than in oöphoritic cyst.
[Illustration: FIG. 174.--Section, perpendicular to the long axis of
the Fallopian tube, showing the relation of a parovarian cyst to the
ovary, the tube, and the peritoneum of the broad ligament.]
=Cysts of the Parovarium.=--Intra-ligamentous in development.
Peritoneal investment which may be stripped off.
Ovary pushed aside, but shape not affected unless the cyst be very
large.
Cyst unilocular.
Wall thin. Fluid contents watery, opalescent; specific gravity below
1010.
May or may not have papillomata in interior.
Tumor of very slow growth.
Usually unilateral.
Fallopian tube much elongated and stretched immediately over the
surface of the cyst.