by continuity of all adjacent tissues, thus affording a contrast to
secondary sarcomata. The glands of the neck are sometimes invaded, but
are unaffected in a considerable proportion of cases. The lungs may be
involved slowly, the growth following the lymphatic paths along the
bronchial or vascular sheaths. The malignancy of lympho-sarcoma is
unquestionable, but as a local growth it is less so than when the
process is general; it is less malignant than cancer or certain forms
of sarcoma.
Carcinoma of the Mediastinum.--Primary carcinoma of the mediastinum, as
separated from the foregoing groups, is relatively rare; even as a
secondary growth the same is true, unless it directly penetrates the
chest-wall from a cancerous breast. The cancerous growths present a
special peculiarity in the fact that they incorporate all the tissues
with which they come in contact, and are followed by contraction.
Carcinoma often originates in the lymph-tissue at the root of the lung,
and may form a mass which may involve the bronchial glands, lower part
of the trachea, the right and left bronchi, and surround the aorta and
oesophagus. Scirrhous cancer frequently originates in the tissues at
the root of the lung surrounding the bronchi and vessels, compressing
them, and extending by branching rays through the lung-substance toward
the periphery, following the course of the large bronchi, the lymph or
arterial vessels. Carcinomatous formation may also originate in the
follicles of the mucous glands of the bronchial tubes, and the mucous
membrane of the same is frequently ulcerated by extension of the morbid
process. The mucous membrane of the bronchi may be covered with
villous-like formations springing from the surrounding growth.[18]
Obstruction of the bronchial lumen by carcinomatous growth may prevent
the expectoration of the bronchial secretions, and dilatation of the
bronchial tubes may be consecutive. These dilated tubes may become
filled with pus from associated bronchitis or forms of catarrhal
pneumonia.
[Footnote 18: See cases by Bennett and Williams, _Lond. Path. Trans._,
vols. xix. and xxiv.; also Burrows, _Med.-Chir. Trans._, vol. xxvii.]
{870} The special pathological characteristics of cancerous growths are
that they exist most frequently in the posterior mediastinum, and
therefore exert special pressure on the respiratory passages. Again,
they are subject to contraction, by which the various pulmonary
structures are fused together. Hard, nodulated, cervical glands usually
appear in the supra-clavicular spaces, affording special contrast in
this respect with the pure sarcomata. Since, in general, the same
tissues may be affected as in lympho-sarcoma or other processes
affecting the bronchial glands, a positive diagnosis can usually only
be made by a microscopic study of the growth. Only one lung is usually
implicated, while the sarcomata spread by extension in all directions
and may involve both lungs.
The effect upon the lungs of mediastinal pressure on the bronchial
tubes may be very serious. Collapse of the bronchial tubes and oedema
of the lungs may ensue, or subacute catarrhal inflammation with
consolidation--a process which has been described by Fuchs as a form of
pneumonia under the title of apneumatosis. The affected tissues not
uncommonly break down by necrotic disintegration, which may lead to the
formation of cavities sometimes erroneously described as resulting from
softening of cancerous nodules.
Pleural effusions are prominent in the clinical history of malignant
intra-thoracic disease, and especially in mediastinal processes. These
effusions are consequent on pressure on the intra-thoracic circulation,
or may be traceable to inflammation, either developed by irritation of
the contiguous morbid process or extension of the same upon the serous
membrane. Purulent pleural collections have been noted in certain
cases, and they may be hemorrhagic. In 31 cases in which the character
of the effusion was mentioned, 6 only were tinged with blood. This
characteristic is therefore simply of relative importance. Pericardial
effusion is also possible from causes similar to those operating upon
the pleural tissues. Pressure may occasion dilatation or thrombosis in
the vena cava. The vessels of the neck suffer, either directly from
pressure inducing dilatation, or by being converted into rigid tubes,
allowing of no adaptation to the amount of blood passing through them.
There may be corresponding collateral swelling of the azygos or
hemi-azygos veins, and at the same time collateral circulation is
established between the jugular and the subclavian on the one side and
the azygos and hemi-azygos on the other through the superior
intercostal veins. The external thoracic veins may, in some cases,
become enlarged, and infrequently compression of the inferior cava may
occasion effusion into the abdominal cavity and cause oedema of the
lower extremities. Morbid growths have occasionally invaded the spinal
canal and excited sufficient pressure to occasion paralysis.[19]
[Footnote 19: Bennett, _loc. cit._]
There are certain forms of mediastinal and pulmonary tumors very seldom
met with; for example, fibromata and osteomata,[20] the latter
sometimes occurring as an exostoses springing from the posterior
surface of the sternum. Dermoid cysts of this region, as in the lungs,
are also most unique. Mohr records the case of a woman æt. twenty-eight
who had spat up hair since her sixteenth year. In the left lung was
found a cyst which communicated with the bronchus. Inside of it was
found several rounded knobs, here and there pedunculated, varying in
size from a nut to a hen's egg, consisting of fibrous tissue provided
with sebaceous and sweat-glands, and from which sprang numerous long
hairs. The remaining contents consisted of fat and balls of hair.
Teeth, bone, and cartilage can sometimes be recognized in these
cysts.[21]
[Footnote 20: _Die Krankhaften Geschwülste_, ii. p. 102; Förster, _loc.
cit._, p. 105; Wagner, _Arch. für Physiol. Heilk._, 1859, p. 411;
Luschka, _Virchow's Arch._, Bd. x. p. 500; Förster, _Ibid._, Bd. xiii.
p. 105; Didardier, _L'Union méd._, 1867, No. 83.]
[Footnote 21: _Nederland Weekblat. vor Geneesk._, 1851, p. 44.]
{871} Enchondroma may occur in the mediastinum or lungs; it is rare as
a primary process, but is more often found as secondary to
enchondromata of the bones.[22]
[Footnote 22: Lebert, _Physiol. Pathol._, ii. p. 213; also, Förster,
_Virchow's Arch._, xiii. p. 106.]
ETIOLOGY.--Predisposing and Exciting Causes.--The etiology of morbid
growths in the mediastinum, as elsewhere, is subject to debate and
conjecture. The most practical query relates to location--viz. that
sarcomatous growths originate in the anterior mediastinum, and
carcinoma more frequently in the posterior.
The trade of shoemaker was followed by several subjects of sarcoma
observed by the writer. These men were accustomed to press the last
against the sternum. With a pure family history free from taint of
malignant disease the etiology of sarcomata may be more readily linked
with some cause of irritation than is the etiology of cancerous tumors.
This irritation may be a blow or other direct injury or some local
irritation, as antecedent inflammatory process in the lungs, bronchial
mucous membrane, or pleura. Intemperance, insufficient food, and
over-exercise have been noticed in rare instances as antecedents. In
reference to lympho-sarcoma, preceding causal irritation may have
existed, but in two-thirds of the cases the etiology is obscure.
Hereditary transmission has not been distinctly proven in regard to any
of the forms of sarcomata. The etiology of cancerous tumors is still
more vague, though possibly the previously-named conditions may have
preceded the growth. Louis, speaking generally upon intra-thoracic
cancer, places it fourth in the scale of comparative frequency of
organs affected--viz. uterus, stomach, liver, and lungs. The history of
the removal of a morbid growth may attest the secondary character of
some growths apparently primary.
In the question of age and sex the autopsies at Kronstadt already
referred to show that in 158 malignant growths 127 were carcinomatous;
81 occurred in men of an average age of fifty-three, and 46 in women of
an average age of fifty-six. So we may conclude that carcinomatous
growths occur after the middle period of life. In 31 cases of
sarcomatous tumors, 20 occurred in men of an average age of
thirty-eight, and 11 in women of an average age of forty-eight. Powell
gives 24.8 as the mean age for the occurrence of mediastinal growths in
general. As a rule, a mediastinal tumor recognized at a relatively
early period of life, before the thirtieth year, is most likely to be
one of the forms of sarcomata. Sarcomatous tumors, however, sometimes
occur in the aged; for example, in a woman æt. seventy-six
(Laboriou[23]) and in a woman over sixty reported by Wilson.[24] The
question of liability through sex is somewhat uncertain, but while
these growths may occur in either, a slight preponderance exists in
favor of the male sex, especially if the growth be a lympho-sarcoma.
[Footnote 23: _Virchow's Arch._, _loc. cit._]
[Footnote 24: _Trans. Path. Soc. Philada._, Jan., 1884.]
SYMPTOMS.--In studying the semeiotic characteristics of mediastinal
growths an accurate history of the case is a prerequisite of paramount
importance to a correct understanding of the essential features of the
malady. It should be borne in mind that no single fact determined by
the methods of physical diagnosis has special pathological
significance, but simply indicates certain definite physical conditions
in the region under examination. The purely objective physical signs
are so closely intertwined with the general symptoms of morbid process
that any study is partial which does not recognize this combination.
Both physical signs and general symptoms must be in turn considered in
connection with a thoughtful analysis of the processes of morbid
anatomy, because symptomatology is the study of the expression of
pathological changes. The general nutrition of patients suffering from
primary sarcoma or lympho-sarcoma is often good in the early stages of
the disease unless the oesophagus is pressed upon or implicated, and at
the last {872} patients may even die in a well-nourished condition.
Indeed, the special import of the peculiar respiratory disturbance with
pain seems set at naught by the appearance of fair health. In some
cases of sarcoma or lympho-sarcoma, however, emaciation is progressive,
though slower than in cancerous growths.
When cancer itself is primary, the ordinary characteristic train of
disturbances of nutrition, with cachexia, follows, and then emaciation
is rapid and decided. The loss of nutrition with anæmia is more marked
in secondary sarcoma, and in cases of secondary cancer cachexia is the
rule.
In reviewing the clinical history attention is specially directed to
the development of the mediastinal growth by the gradual increment of
subjective sensations of shortness of breath, with a sense of
discomfort or tightness in the chest, with or without radiating pains.
The respiratory phenomena present great diversity, yet the neurotic
character of the dyspnoea is characteristic. Rest or change of posture
may remove all oppression, or on the least exertion dyspnoea may be at
once manifested. With limited physical signs there may be great
distress of breathing or orthopnoea, while in many cases with
unquestioned evidence of tumor there may be only a little quickening of
respiration. As a rule, tumors of the anterior mediastinum are less
characterized by dyspnoea than those involving the posterior space. The
dyspnoea depends upon the size and seat of the tumor, and increases day
by day with its growth; but in certain cases the tumor is so placed
that pressure on the trachea, bronchus, or direct pneumogastric
irritation may induce severe paroxysmal attacks of dyspnoea, with
laryngeal symptoms resembling the condition so common in aneurismal
tumors. Pressure symptoms, traceable to irritation of the
pneumogastrics, are, however, as a rule, less marked than in aneurism.
Pressure on the trachea without implication of the laryngeal nerves can
occasion many of the symptoms usually assigned to the latter cause.[25]
Even when the tenth nerves have been surrounded or involved by the
growth, special symptoms may be absent, although in other cases serious
phenomena follow, such as vomiting or other gastric disturbance, or
even inability to swallow; sometimes palpitation, angina, irregular
action, or tendency to faintness may follow implication of the cardiac
plexus.
[Footnote 25: Bristow, _St. Thomas's Hosp. Rep._, vol. lxxi.:
"Influence of Pressure on Trachea without Implication of the Recurrent
Laryngeal Nerves."]
The symptom of pain is usually far less than in cases of aneurism,
since it is only in rare instances that the chest-walls become eroded
by the outward pressure of the tumor, as so frequently occurs in
aneurism. Moreover, the growth more readily adapts itself to the
contour of the chest, and tends to envelop rather than compress organs
or nerves. From the time that pressure commences, either on the
trachea, bronchi, or intra-thoracic nerves, cough is more or less
constant. It may, however, be due to pulmonary changes occasioned by
the pressure or actual involvement of the lung by the growth. Cough is
an earlier symptom when the growth is situated in the posterior
mediastinum than when it is located anteriorly. It is usually laryngeal
and ringing in timbre, and may occur paroxysmally, as in pertussis. It
is ineffectual, dry, or attended with only scanty mucous or frothy
expectoration. The sputa may be tinged with blood, or profuse
hæmoptysis is a possible symptom. A microscopic examination of the
sputa in a case of intra-thoracic tumor is always important, because
portions of the morbid growth may be found, or by perforation of the
trachea or oesophagus the pus from a mediastinal abscess may be mixed
with the sputa. Mediastinal tumors are not, as a rule, characterized by
febrile symptoms. Inflammatory complications of the lungs or pleura may
account for the exceptional thermometric variations. Cases have been
reported by Bennett and Church in which there was persistent elevation
of temperature, with daily fluctuations and rapidity of pulse and
respiration. In one instance of lympho-sarcoma the paroxysms of fever
corresponded with the periods of {873} growth in the enlarged glands,
but in this case the lymphatics of the general system were also
implicated. From the fact that the growths are strictly mesial,
dysphagia is a far more common and persistent symptom than in aneurism,
especially in growths of the posterior mediastinum. When the growth is
situated in the anterior mediastinum the dysphagia is less frequent;
but it must be borne in mind that prolongations of the tumor may
occasion lateral oesophageal pressure, or narrowing of the lumen of the
oesophagus can occur from pressure upon the trachea by the growth.
Exceptionally, dysphagia may be due to implication of the oesophagus in
the new growth. (See Cancer of the Lung.) Neural influences may
increase the dysphagia, in which case it is doubtless a reflex
phenomenon and is associated with hiccough or vomiting. The passage of
a bougie can be readily effected in such cases.
In reference to the foregoing pressure symptoms one fact deserves
recognition--viz. that in aneurismal tumors the pressure symptoms are
subject to variations in intensity due to changes in the
intra-aneurismal tension, while in morbid growths in the mediastinum
the pressure symptoms exhibit a progressive tendency, advance upon the
same lines, and are more constant than in aneurism. With this principle
in mind, the additional pressure symptoms in doubtful cases of
mediastinal growth must all be considered; for instance, in some
histories recorded by Rossbach the pupils could be dilated by firm
pressure on the tumor above the clavicle. The pulses in the brachials
or radials may be unequal, and variations of rhythm, volume, and rate
may be noted as evidences of pressure, which may occasion thrombosis by
retarding the circulation in the innominate, subclavian, or azygos
vein. The blood may reach the heart by the collateral circulation
elsewhere described or by the dilated mammary superior and inferior
epigastrics and the inferior vena cava. Pressure may therefore give
rise to cyanosis, oedema of the upper or lower portions of the body,
with enlargement of the superficial veins, or dropsy may be traceable
to hydræmia.
PHYSICAL SIGNS.--When mediastinal tumors are of small size, physical
signs may afford no help in making a diagnosis, and they will always
vary according to the location of the growth.
Inspection may reveal venous repletion of the veins of the face and
neck, with distension of the superficial veins of the chest; the latter
symptom is more frequently obvious than in aneurism. In the case of
sarcoma represented by Fig. 53 the foreign growth was so limited to the
mesial line as not to involve the vessels or create pressure symptoms
upon them. If the anterior mediastinum is implicated, there may be
circumscribed alterations in the contour of the chest. Prominence of
the upper piece of the sternum and of the sternal attachment of one or
more ribs may be recognized. The sternum itself may appear thickened
upon palpation of the notch. One side of the chest may be larger than
the other above the nipple-line; the affected side, however, may be
smaller, since vicarious respiratory function may create distension.
The usual changes in the contour of the chest-walls will indicate
pleural effusions. (See Cancer of the Lungs.) Since tumors of the
anterior mediastinum overlie the aorta, transmitted pulsation may be
detected in rare instances; this pulsation can be differentiated from
aneurismal vibrations by the absence of the sense of expansile
pulsation characteristic of dilated aorta or aneurism, but it sometimes
closely resembles that yielded by an aneurismal sac thickly lined by
coagulum.
Lympho-sarcoma and cancer are often accompanied by painless, movable
glandular enlargements, recognizable by palpation in the
supra-clavicular spaces; but the absence of the glandular implication
in sarcomata is conspicuous; swelling occasionally manifests itself in
the suprasternal notch. Tumors of the posterior mediastinum must attain
considerable size before {874} they can be recognizable by the
foregoing methods. Growths in the latter space are those especially
liable to complication by pleural effusion in one or both sides.
Mediastinal growths may occasion collapse of the lung, or cirrhotic
processes or pleural adhesions may diminish the circumferential
measurements of the chest. The heart may be displaced backward,
downward, to the left or to the right side; and since in aneurism,
uncombined with valvular disease, little cardiac displacement occurs,
this sign is of importance. Rarely, as in Cotton's case in Brompton
Hospital, the heart may be fixed in situ by the extension of the growth
on both sides of it.
Percussion.--It has been observed that a very small tumor may, from its
particular site, at a very early stage give rise to symptoms both of
pressure and disordered innervation of great severity, whilst another
may attain considerable magnitude before the patient experiences any
distress or any decided evidence of pressure is manifested. It is
equally true that percussion and auscultation may be most valuable, or,
on the other hand, indefinite. The degree of dulness occasioned by a
morbid growth in the anterior mediastinum is dependent on its size,
large growths yielding flatness; but when the tumors are small the
osteal resonance of the sternum is simply hardened. Respiratory
percussion is available if the growth lies anteriorly. The full, clear
resonance of full-held inspiration contrasts with the increased dulness
developed when the lungs are stripped from the mediastinal space by
forced expiration. The boundaries of the growth on either side of the
sternum may be defined by percussion, and it is possible that the
greater part of one side may be occupied by the new formation. The
adjacent tissues are involved by direct invasion, or indirectly by
extension along the bronchus from behind forward, thus involving the
middle tier of the lung. Mediastinal tumors therefore in their mode of
growth yield a contrast with pleural effusions, because the latter
usually advance steadily from below upward. When the growth is located
in the posterior mediastinum, percussion should be practised after the
manner recommended by Mussey to facilitate recognition of enlarged
bronchial glands. (See Pulmonary Syphilis.) The apices, humeral,
scapular, basic, or marginal regions often yield a tympanitic type of
resonance, since they are often in a condition of vesicular emphysema.
The pericardial sac may be distended with effusion or implicated in the
growth, and an area of pyramidal dulness with the base above may be
recognizable.
Auscultation.--In growths situated anteriorly, in the mesial line, one
of the most forcible lessons may be impressed by the distance and
obscurity of the second sounds of the heart over the aortic and
pulmonary artery, cartilages, or the upper piece of the sternum. The
cardiac sounds may be transmitted downward, and can be heard distinctly
in some abnormal position. Even a murmur can occur due to compression
of the aorta, or pericardial friction. The respiratory murmur will
probably seem feeble and distant over one or both apices, and whistling
near the trachea.
If the posterior mediastinal space be involved, the respiratory murmur
may represent some type of bronchial breathing, or if the lumen of the
trachea or one of the bronchi be decidedly lessened, the respiratory
murmur may be whistling, feeble, or suppressed over the affected side.
Over the other bronchus the respiratory murmur may be more high-pitched
than in health, and slightly exaggerated. The rhythm is often jerky and
paroxysmal; the paroxysms are more or less constant, but are liable at
times to increase. Auscultation should be especially practised over the
roots of the lungs or in the neighborhood of the second dorsal
vertebra. Frequently it can be demonstrated, both by auscultation and
percussion, that there is diminished air-supply to one or other of the
lungs, while the respiratory murmur is not sufficiently changed for
classification. The respiration may acquire a stridulous or sibilant
character, most marked on expiration, but {875} less often than in
aneurism, because there is a greater tendency to occlusion of the
bronchi. It should always be remembered that the lung undergoes very
various and opposite changes as the result of pressure on the bronchi,
interrupting the entrance and egress of air from the lobules, and the
physical signs of emphysema, infarction, congestion, or consolidation
may exist in one or the other side. The ordinary methods of physical
examination indicate the existence of pleural effusions, but large
growths extending from the mediastinum or originating in the lung may
so closely simulate such effusions that a positive diagnosis can be
arrived at only by paracentesis.
When tumors exist in the form of very small nodules as diffused
sarcomata, no changes in the character of the respiration may be noted.
Friction râles and pleuro-pericardial frictions may be heard in some
cases. Distension of the bronchial tubes from pressure may occasion the
dilatation of the distal bronchial passages and pulmonary lobules with
retained muco-purulent secretions. The cross-sections of the bronchi
have been described as multiple abscesses. Areas of collapse or slow
inflammation with softening of the secondary inflammatory product can
follow. The bronchial pressure may prevent the sufficient transit of
air through the bronchi to create râles, or moist râles indicative of
tracheo-bronchitis or oedema may abound.