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TERATOMAS AND THEIR RELATION TO AGE H. E. HIMWICH
From Department of Pathology, C m e l l University Medical
College, New York
Received for publication May 10, 1922
The great accumulation of reported cases of teratomas offers an
excellent opportunity to review the data, with the object of
investigating the relation of their frequency to the age of the
host. In the course of the study, it has become apparent that this
relationship is so definite as to assume the form of a gen- eral
law.
The largest collections of teratomas were gathered by Taruffi
and Ahlfeld. Both of these observers stressed the large con-
genital forms which are situated in the head, the thoracic, the
abdominal, or the sacral regions. Gonadal teratomas occur most
frequently in early adult life (Wilms). Among others, Askanazy
investigated the internal craniopagi, and Ekehorn, the internal
thoracopagi. Lexer and Kakayama studied the abdominal inclusions
and pygopagi.
Though many hypotheses have been advanced on the origin of
teratomas, they may be resolved into two view points: The teratoma
is either the offspring or the twin of its host. Stockard has
recently produced experimental evidence in favor of the latter
conception.
CRITERIA AND METHODS OF STUDY
Two precautions have been observed in compiling the present
statistics: (1) Only growths of tridermal or bidermal origin have
been considered. KO such case has been omitted. (2) Special effort
has been exerted to determine the age at which the teratoma began
its growth. The first increase in size of external growths may be
accurat,ely observed. For those
26 1
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262 H. E. HIMWICH
situated internally, the initial symptom was used as an
indicator. Where the history was deficient, the age at which the
operation took place or at which death occurred was taken as the
closest approximation obtainable. The last criterium particularly
applies to the teratomas of the aged. In this manner 895 cases have
been studied. Sometimes a period of slow growth is followed by one
of heightened activity. Such is the case of chorioma testis
reported by Jackson, in which growth commenced at the age of twenty
and slowly continued to twenty-three, after which the increase in
size became extremely rapid. Since the relationship between the
growth of the host and that of the teratoma is of interest, in such
cases, the beginnings of both periods have been noted. A similar
effort was made for internal teratomas, thus bringing the total
number of growths tabulated to 975. In systematizing the results it
was noted that though the
variation from year to year is considerable, there seems to be
an orderly waxing and waning of the number of cases to an extent
which justifies the drawing of a curve. An average has been drawn
in order to minimize accidental variation. Six year periods have
been chosen because they are the longest which correspond to actual
changes throughout the length of the curve. The first period begins
at fertilization and ends at five. In the curves which are drawn to
a scale of one-half, the abscissae represent the age of the host
when the tumor began its growth, the ordinates the number of cases
in each year.
THE CURVE FOR ALL TERATOMAS
After an initial maximum rise, the curve falls and remains low
from five to eleven years (fig. 1). At eleven it achieves a higher
level, which is increased at seventeen and twenty-three years. The
second maximum is found between twenty-three and twenty-nine years.
The curve falls gradually at twenty-nine and thirty-five years, and
then more rapidly at forty-one, after which it becomes
progressively lower towards its end at seventy- six years.
Eighty-seven per cent of the teratomas occur before forty-one years
and 95 per cent before fifty-three.
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TERATOMAS AND "HEIR RELATION TO AGE 263
.
Most congenital teratomas do not evince postnatal growth and
since this study concerns only those which do grow, for the early
maximal total may be substituted the smaller number of tumors,
showing power for growth, represented by the low@ broken line in
the graph. With this correction the highest point in the curve is
found between twenty-three and twenty-nine years. This is borne out
by Wilms who finds the period of greatest frequency for sex-gland
teratomas to be between the ages of twenty and thhty years. His
conclusion is to be expected because teratomas occur most
frequently in aex glands.
..-. . I @ I I I I I I
r
Fro. 1. CURVE FOR ALL TERATOMAB The abscissae stand for the
years of appearance of growths, the ordinates for
the number in each year. Both are drawn to a scale of one-half.
The total number of congenital tumors is not shown. The dash line
indicates the average for each six-year period. In the first six
years there are two; the upper one stands for all cases, the lower
for those which had power of postnatal growth. The mode is from
twenty-three t o twenty-nine, the timo when growth stops.
STUDY OF THE CORRECTED CURVE
There are three aspects of the described phenomenon: First, it
is evident that the total number of teratomas at any age increases
with the actual growth of the individual. As size
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264 H. E. HIMWICH
increases, the total number of teratomas increases. But it must
be remembered that while size is increasing, growth rate is
falling. Therefore, second, teratomas become more frequent as
growth slows down, at the time when growth potential be- comes
smaller. Growth must be recognized as involving two elements:
increasing actual proportions, and decreasing growth potential.
Hence, third, the total number of teratomas at any age increases as
growth potential diminishes.
When one recalls the fact that the changes in growth rate are
not constant, the number of teratomas is seen to bear even a closer
relationship to the growth of the hosts than has been indicated.
Not only do these tumors appear as growth of the host slows, but
during their time of appearance the teratomas are more frequent in
the periods of slower growth of the host. Teratomas are common in
early infancy following a space of the most rapid proliferation of
all-fetal growth. They increase again when the comparatively rapid
growth rate of earlychild- hood gives way to the slower one of
pubescence and lastly they are found in greater numbers as active
growth gradually ceases.
To explain the relative number of teratomas appearing in the
several periods we must take into consideration an additional
factor, the growth potential of the embryonal rest, for a teratoma
by most theories arises in an embryonal rest of some kind. It is
known that the great majority of embryonal rests do not grow; they
either degenerate or remain dormant. Others achieve a more or less
perfect adult growth, while a few develop into tumors. Tridermal
rests act in a similar manner. Thus we have a few with high growth
potential, many with less capacity for growth, and finally others
which remain latent unless they are stirred to development by an
external stimulus.
During the first six years of life the growth rate of the host
declines rapidly, bis growth potential is greatly reduced, and the
number of teratomas of relatively higher potential, capable of
proliferation, is comparatively large. From five to eleven years
the growth rate is fairly constant, the loss of potential is small,
and the additional number of teratomas released is few. The next
appreciable change takes place during the differentia-
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TERATOXAS AND THEIR RELATION TO AGE 265
tion occurring a t puberty and accompanying the maturation of
the sex organs. Here the number of teratomas begins to increase and
continues to do so until growth finally stops, at which time the
greatest number of teratomas make their pres- ence known. Although
the loss of growth potential in the host becomes smaller, being
least in the final period from twenty- three to twenty-nine years,
yet just because growth itself is slow, there is an ever increasing
number of embryonal rests of low potential, capable of expressing
their latent growth energy. The very inactive rests even a t this
period do not have suficient energy to start growth spontaneously
and are therefore consid- ered in another group at a later time.
However, they may serve as a nidus for neoplasms since many do
commence development after the growth of the host has stopped.
Thus the number of teratomas appearing a t any given time
depends upon the amount of loss in growth potential of the hosts
during that time and the number of rests whose potential is large
enough to proliferate under these conditions. Evidently the number
of teratomas in any period varies inversely to the growth potential
of the hosts and directly as that of the embryonal rests.
ANALYSIS OF CURVES OF AGE INCIDENCE OF TERATOMAS IN THE
DIFFERENT LOCATIONS
The object of this study is to show the relation to the general
law of the occurrence of teratomas in the various situations.
Ekehorn in his collection of teratomas of the anterior
mediastinum finds fifteen cases occurring between the ages of
twenty and thirty, four between thirty and forty years, and four
more to sixty, thus agreeing with the present curve in showing the
maximum occurrence from twenty-three years to twen ty-nine.
Abdominal inclusions. The abdominal tridermal growths are
frequently discovered a t birth but continue to be found throughout
life, with a second rise from twenty-three to twenty- nine
years.
Craniopagi and pygopagi. There is not a sufficiently large
number of head and sacral teratomas to yield reliable
statistics.
Thoracopagi.
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2G6 H e E. HIMWICH
4 3 10 8 12 14 10 11 8
10 6 3 1 2 2
103
Statistic8 of varioue authors. They ahow a cloee agreement with
or@inul statwlkr here presented. Note increaaed number of dermoida
during pubeSCeM8
-- 0-5
6-17 18-24 25-29 30-34 35-39 40-44 45-40 50-59 80-75
--
5 0 16
11 11 7 3
2 2
61
-- 0-19
20-25 25-30 30-35 3540 40-45 45-60
4 6 0 - 6 0 80-63
--
46 1 1 4
2
279 33 70
114 144 118 94 45 30 10 10 8 6
OARCINOYAB - D v u p
11 26 48 19 20 21 10 10 14 14 1
-
- 207 -
- 1 19 7 2 2
- 31
- 1-5 6-10
10-15 15-20 20-25 26-30 30-35 36-40 40-46 4b-so 50-55 56-60
60-66 86-70 70 + -
I - 0 1 8 8
19 14 4 2 2
- 69
0-5 6-11
11-17 l.7-23 23-29 29-35 36-41 41-47 47-63 63-69 59-66 65-71
- -
2 2 1
12 29 30 34 27 10 8 1 1
- 167 -
10-20 20-30 30-40 40-50 so+
Incluiona according to age and situation. Those which are
capable of growth appear in greater number from twenty-three yeara
to twenty-nine years
?TQOPAOI I TOT'AL AOB .BDOYINAI P A B A I I T I B OVARIAN
DRATOYAB rnOR*O- OPAQI RAMOPAQ 78 1 4 4 1
2
90
30 6
18 16 20 15 8 4 4 1 2 1 1
17 16 27 44 52 47 39 22 19 13 10 0 2
48 7 9
32 55 44 43 15 7
3 1
264
-5 6-11
11-17 17-23 23-29 29-36 35-41 41-47 47-53 53-69 69-65 66-71
71-77
Total. . . .
55 3
11 14 16 10 4 4 4 1 1
123 132 --
63 I 976 313
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TERATOMAS AND THEIR RELATION TO AGE 267
Most are congenital. The internal craniopagi occur most
frequently from eleven to twenty-seven years. The only year where
there is more than one case is the nineteenth, where there are two.
The last teratoma capable of spontaneous growth appeared at
twenty-seven. The later examples of sacral tera- tomas are even
rarer than those occurring in the head. There is one each at ten
and thirteen years and four from nineteen to twenty-three.
Ovarian terakmas. Turning next to the gonadal teratomas and
comparing the testicular and ovarian curves, we eee that the latter
is less variable (fig. 3). This is due to the delayed diagnosis of
so many of the ovarian teratomas, probably because of their slow
growth, as their structure is often of the adult type. Their
internal position further postpones their discovery, yet dermoids
are sometimes found by accident. Nevertheless, the largest number
of tumors occurs between the ages of twenty- three and twenty-nine.
From a review of one hundred and three case8 Pauli fmds dermoids
appearing most often from twenty to thirty years.
Another difference between the ovarian and testicular curves is
the greater rise in the former in the two periods between eleven
and twenty-three years. This phenomenon might be expected as a
result of the growth differences since, in the male, postpubescent
growth is more rapid than in the female.
Teratoma testis. The external situation of the male sex gland
allows prompt discovery of its tumors. Although the greatest
decline in rate of growth occurs early in life from birth to four
years and the number of testicular teratomas at this time is large,
the maximum number nevertheless occurs at a later period. This is
probably due to the fact that growth under four years is
comparatively very rapid in spite of its fast declining rate. The
modal year of the curve is twenty-six, It is interesting to note
that the last growth cartilage of the long bones ossifies at
twenty-five.
Teratomas in the testes commence growth most frequently between
the ages of twenty-three and twenty-nine years. Che- vassu finds
the maximum between twenty and thirty years (fig. 2).
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268 H. E. HIMWICH
TERATOMAB OF LATER LIFE
After establishing the time of greatest frequency of teratomas,
it still remains to account for those of old age. Those diagnosed
after the age of fifty-one may be divided into two groups. The
first consists of neoplasms of adult structure which had reached
the limits of their capacity for post-natal growth, while those of
the second are more malignant. To the first group belong such
tumors as the following:
Craniopagi. Beck reports a case in which a dermoid was found at
autopsy in place of the hypophysis in a woman seventy- four years
of age. Eberth reports a similar accidental finding beneath the
dura in a woman of seventy-five.
Thoracopugi. There are two examples in Ekehorn’s collec-
tion-Pinder’s case of a patient with bulbar paralysis, aged fifty-
three, in whom the dermoid was discovered at autopsy; and Lebert’s
of a man of sixty who had been dyspneic since his six- teenth
year.
Abdominal inclusions. Rizzoli (Taruffi) reports two cases of
late abdominal inclusions, one at sixty, the other at sixty-two.
Symptoms had been present for a long time in both. In one of the
cases they appeared first at the age of twenty.
The tumors mentioned thus far were benign, though some produced
symptoms because of their size and position.
In the second group of neoplasms the element of trauma be- comes
important in the etiology. There is Bonney’s report of a
retroperitoneal chorioma of a man of sixty-seven, and Goebell’s of
an abdominal teratoma that became malignant a t fifty-four,
twenty-seven years after a mass had been diagnosed. Djewitski
reports a chorioma of the bladder which first gave symptoms at the
age of seventy-three. The same irritation which produces a
papilloma of the bladder may transform an otherwise benign
embryonal rest.
Pygopagi. Hudson describes a sacral teratoma which began growth
at the age of fifty-two; the history shows that a nodule had
existed in that region since the birth of the patient. The
histological picture is one of a tridermal rest with cancerous
degeneration of mucous glands. It is similar to an old age
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TERATOMAS AND THEIR RELATION TO AGE 269
cancer arising in previously normal tissue. Evidently in the
last four cases it is not growth potential of the embryonal rest
but an extrinsic traumatic influence, to which every part of the
body is subject, that caused the proliferation of cells. A case of
Briddon’s beautifully illustrates both these factors occurring in
the same growth but independently and at different times. It
concerns a sacral dermoid which appeared externally a t the age of
twenty-two and then ceased growth till the fifty-second year, when
it underwent epitheliomatous change.
Teratoma testis. There are three examples of late teratoma
testis. Lexer quotes one from v. Bergmann’s clinic in a man of
sixty. On section the growth was of adult structure.
Ewing and Pepere report cases which first showed growth a t the
ages of sixty-one and sixty-three, respectively. The micro- scopic
examination in both instances showed carcinomatous change of one
element in rt totipotent rest.
Ovarian teratmnas. Of thirty-two dermoids, thirteen exhibited
malignant transformation of a carcinomatous, sarcomatous, or
endotheliomatous type. Four showed thyroid structure, of which
three were rapidly growing tumors. In six reports de- tails were
lacking. However, since the growths were called dermoids, their
structure must have been of the adult type, like that of the
remaining nine inclusions.
To summarize, the late appearance of stationary teratomas is due
to their delayed discovery, while that of growing teratomas is
caused by their injury.
Carcinoma testis is discussed in this place not only for its
possible teratomatous origin, but because trau- matic etiology
links it with the tumors of later life. In many cases of teratoma
testis in young people the transformation of a slowly into a more
rapidly growing tumor is caused by trauma. In older people the
growth is rapid from the start. The same se- quence of events
obtains for carcinoma testis. The cell of many cases of carcinoma
testis is characteristic, with a large nucleus and clear cytoplasm.
Sometimes the growth is called a sarcoma; the difference in opinion
is due to the fact that no analogous cell is found in the human
body. This same cell is
,
Carcinoma testis.
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270 H. E. HIMWICH
often found with teratoma testis. There are only two probable
interpretations: (1) The irritation caused by some extrinsic
factor, in this special case, by the teratoma on the tubule cells,
is the cause of carcinoma. (2) The unique type of cell is of
teratomatous origin. Chevassu takes the position that it develops
from the adult spermatogonia, putting the tumor in the class of
acquired carcinomas. The final convincing link in the chain of
evidence has not been produced, for he has not been able to trace
the steps of anaplastic change from the sperma- togonia to the
carcinoma cell.
It has been definitely established that the cell which is of
more rapid growth will often overrun and may finally crowd out
alto- gether the other constituents of the tumor. Thus arise the
rhabdomyomas, the chondromas-the simple tumors of the sex glands.
In this uncontrolled competition the most embryonal type of cell
would have a decided advantage. Therefore Ewing concludes that
carcinoma testis is a one-sided teratoma. In the light of the
foregoing it is interesting to see to which of these two theories
the carcinoma curve lends itself.
According to Chevassu’s statistics embryomas occur with greatest
frequency from twenty-five to thirty years and semino- mas from
thirty-five to forty (fig. 2). The writer’s review of a larger
number of cases coincides with the data of Chevassu, the modes
occuring from twenty-three to twenty-nine years in the teratomas
and thirty-five to forty-one years in the carcinomas.
Comparing the carcinoma testis curve with that of all cancer
(Hoffmanl), of which the congenital cases are too small a
propor-
Mortality from cancer throughout the United States Registration
Area. All organs and all parte. 1903-1912. (Hoffman, The Mortality
from Cancer.)
Until 10 10-24 25-34 35-41 45-54 65-04 65-74
75 and over
1,170 2,028 3,767
10,750 24,431 35,327 33,745 i a , ~
984 1,844 7,891
26,779 46,669 62,393 43,010 24,801
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TERATOMAS AND THEIR RELATION TO AGE 271
tion materially to alter the general outline, we see that the
former has no resemblance to the latter, for in that case it would
have a continuous rise to some time after sixty. In brief, the
carcinoma testis curve is the teratoma testis curve with themode
slightly shifted.
Since the histogenesis of carcinoma testis has not been traced
from either embryonal or adult tubule cells, it is probable that
carcinoma testis is of nontesticular origin, and since there is no
reason why misplaced cells should so often be of the same type or
occur so frequently with teratomas, unless they are of tera-
Fro. 2. TESTICWLAR TERATOMAS The lower two curves are reproduced
from Chevassu’s paper. The con-
tinuous line represents the teratomas; the dash line, the
carcinomas. In order better to compare the new curves with those of
Chevassu, the number of tera- tomas in each year was divided by
four, and that of carcinomas by two. Both curves are plotted on a
basis of ten-year periods.
tomatous origin, we are forced to this conclusion towards which
the study of the curve gives additional evidence. Similarly to
teratoma test,is, carcinoma may show a congenital increase in the
size of the organ. Morestin (Chevassu) reports such a tumor, which
assumed malignancy at the age of thirty-seven. Like-
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272 H. E. HIMWICH
wise carcinoma occurs more often in undescended testicles. It
begins its growth in the rete and, like teratoma testis, is occa-
sionally observed in pseudohermaphrodites.
The origin of primary tumors of the ovary is so undecided that
any data in reference to them is of particular interest. Here we
shall mention a few facts in regard to one of these tumors which
may be of teratomatous origin, i.e., the sarcoma.
Ewing divides these sarcomas into three main types: (1) spindle
cell; (2) round cell; (3) myxoma cell. This classification is of
special significance since just such types of sarcomatous de-
generation of dermoids have been observed (Debucy).
Ovarian tumors.
FIG. 3. OVARIAN TERATOMAS These curves are averages for six year
periods drawn to a scale of one-half.
The continuous line represents the teratomas with the mode from
twenty-three to twenty-nine years; the dash line the carcinomas
with the mode from eleven to seventeen years, the period of
pubescence.
Desurmont finds that the different primary tumors are bilateral
to varying degrees. However, sarcomas, 25 per cent, and der- moids,
20 per cent (Pauli), approximate each other quite closely.
Finally, the most common tumor of infancy is the sarcoma, which
is most frequent at fifteen years (Donhauser). Cordier and
Zangemeister give fifteen and twenty years, respectively, as the
age of most common occurrence of sarcomas. They are found from
fifteen years to twenty-five and from forty years to fifty
(Desurmont), both periods of physiological stimulation, The writer
finds the mode of the combined carcinoma and sar- coma curve at
fifteen years (fig. 3). Comparing the mode of this curve with that
of ovarian teratomas, we find that it has been shifted forward to
the time of pubescence. Hence there is a group of embryonal cell
tumors having an age incidence simi- lar to teratomas, and becoming
malignant under the stimulation of puberty.
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TERATOMAS AND THEIR RELATION TO AGE 273
FACTORS I N T H E ETIOLOGY O F TERATOMAS
The growth of the earlier teratomas may be adequately ex-
plained on the basis of a growth competition between the host and
the embryonal rest. But even in the teratomas of infancy another
factor, trauma, may be present. It becomes increasingly important
later on.
Growth potential. The growth of the host inhibits that of the
teratoma.
The growth of the embryonal rest may be divided into two parts:
its prenatal development, or growth which continues until stopped
by the inhibition produced by the excessive growth of the host; and
the growth of which it is still capable (growth potential) after
that of the host slows down or ceases. These two parts are in
reciprocal relation to each other. The earlier the prenatal
inhibition, the smaller and less differentiated will be the
inhibited rest but the greater will be the remaining growth
potential. Small embryonal rests may develop proliferative powers
while large ones, which achieve a certain intrauterine development,
seldom if ever show further capacity for spontaneous growth.
The shift in the mode of the curve of carcinoma testis from
twenty-three to twenty-nine years to thirty-five to forty-one years
is due to an external stimulus.
In spite of the larger growth potential of the smaller
testicular rests many do not achieve malignancy until their
immediate region is traumatized. This is illustrated on comparing
these tumors in the testicle and the ovary. A larger proportion of
the latter are benign, forming adult structures. The chief
difference in their histories is due to their locations; the
testicle is exposed to injury, the ovary is not. It is generally
admitted that teratomas do not become malignant much oftener than
do normal tissues.
In the case of carcinoma testis we should expect with a history
of injury to a small undifferentiated rest and the resulting pro-
liferation of an embryonal cell, a shift in the mode of the cwve
towards that of old age cancer.
Trauma.
TED JOURNAL 01 CANCER nmmutx, VOL. VI, NO. 4
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274 H. El. H M I C H
SUMMARY AND CONCLUSIONS
i. Growth potential and teratomas
1. Parasite. Teratomas are tridermal embryonal rests en- dowed
with a certain amount of possible growth, i.e., growt,h potential.
When the rest is comparatively large it has necessarily consumed
considerable growth energy before birth, while in the small
teratoma, the growth period may be divided into two parts, a slight
early growth soon followed by an inhibition, and a later, or
post-natal growth, should conditions permit.
2. Host. The total number of teratomas in a population, up to
any given age, increases while growth potential of the hosts
decreases. As the Iarger increases in the number of tera- tomas
occur in periods when growth of the host is slowed most, the growth
of the host must inhibit that of the embryonal rest.
3. The number of teratomas appearing in any given time varies
inversely with the growth potential of the host and directly as
that of the embryonal rest. The tumors which begin their postnatal
growth before that of the host stops are of highest potential, but
are not necessarily more malignant, for they must overcome a still
present inhibition. Since most teratomas have a low growth
potential, they appear most commonly at the time the growth of the
host stops-from twenty-three to twenty- nine years.
I I . Trauma and autono?nous growths
1. Teratomas which start growth as a result of injury are
malignant more frequently than those which proliferate solely under
t,he influence of growth potential.
2. When trauma precipitates growth, the teratoma is fre- quently
monodermal. If the inclusion is still in an undifferen- tiated
condition the cell is often of an embryonal type. If a developed
inclusion is traumatized the cell in many instances is like that of
acquired cancer.
3. The curve of carcinoma testis rises and falls in a manner
similar to that of teratoma testis and not like that of old age
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TERATOMAS AND THEIR RELATION TO AQE 275
cancer. This is another fact which may be adduced in support of
the theory that carcinoma testis is a one-sided teratoma. In the
female, a similar neoplasm might be expected to arise as the result
of the physiologic stimulations of puberty, This is what actually
takes place, hence the growth, in all probability, is of
teratomatous origin.
4. Trauma is followed by proliferation of cells, and any pre-
cipitant of regeneration may be important in the etiology of
acquired cancer. I n the old the inhibition of the organism is
almost negligible. Hence trauma at that time may readily be
followed by an uncontrolled and therefore excessive growth. Thus,
loss of growth restraint may be almost as important a factor in the
etiology of acquired cancer as in that of congenital
inclusions.
REFERENCES
BARRON: Teratomata of the brain, Jour. Cancer Res., 1916, i,
311. CIIRI~TIAN: Dermoid cysts and teratomata of the anterior
mediastinum, Jour.
Med. Ree., 1902, vii, 54. DE~URMONT: Etude anatomo-clinique des
tumeurs solides bilateralea des ovares,
These de Paris, 1911-1912. EWING: Neoplastic Diseases,
Philadelphia, 1919. EWING: Teratoma testis and its derivatives,
Surg., Gynec. & Obst., 1911, xii, 230. LEXER: Ueber teratoide
Geschwulste in der Bauchhohle und deren Operation,
NAKAYAMA : Ueber Congenitale Sacraltumoren, Arch. f.
Entwcklngsmechn. d.
STOCKARD: Developmental rate and structural expression, Am.
Jour. Anat.,
TARUPPI : Storia della Teratologia, 1S61-1694.
Arch. f . klin. Chir., 1900, lxi, 646.
Organ., 1905, xix, 475.
1920-1921, xxviii, 115.
These references were chosen out of over one hundred and sixty;
they contain extensive reviews of the literature consulted.