SOLITARY
PULMONARY
HYDATID
CYST
Report
of
a Case
and
Discussion
of
Its
Differential
Diagnosis
Eduardo Vachier, Captain, MC, AUS, and David C. Hillman,* Captain, MC, AUS
Kimbrough Army Hospital, Fort George G. Meade, Maryland
(Submitted June 10; accepted for publication October 7, 1964.)
This material has been reviewed by the Office of The Surgeon General, Department of the Army, and there is no objection to its presentation and/or publication. This review does not imply any
indorse-ment of the opinions advanced or any recommendation of such products as may be named. Dr. Hillman
is Chief, Department of Radiology. Dr. Vachier is in the Department of Pediatrics.
ADDRESS (E.V.) : Rodriguez Army Hospital, APO 851, New York, N.Y. 10000.
PEDIATRICS, April 1965
699
H
YDATID DISEASE is common throughout pastoral regions of the world,par-ticularlv common in Australia, New
Zea-land, the Middle East, South America, and
some European countries. It is rare in the
United States. Modern methods of
trans-portation may increase the number of cases
seen in this country by increasing the
popu-lation exposed through world-wide travel.
Few cases are indigenous to the United
States, with some states reporting one or
none a year.1
Two species of Echinococcus can
para-sitize man, Echinococcus granulosus and
Echinococcus multilocularis.2 The life cycle
of the commonest etiologic agent, E.
granu-losiis is well known.
The cyst may be clinically latent for many
years. However, when the cyst begins to
grow, its average rate of growth is 2 to 3
cm per year. The rate of growth is partially
determined by the pressure resistance of
the host’s tissues. The rate of growth will
be greater in the lung than in the liver or
spleen. A high resistance to growth by
sur-rounding tissue will also increase the
endog-enous vesiculation of the cyst.
The cyst is composed of two histologic
layers. The external layer, or ectocyst, is
thick and white in color, similar in
ap-pearance to an egg shell and is not involved
in the proliferation of the cyst. The inner
layer, or endocyst, is the germinative layer
which is responsible for the formation of
daughter cysts by endogenous vesiculation.
There is a third anatomic component, the
penicyst, which is not formed by the hydatid
cyst but is a host tissue response to the cyst
composed of inflammatory and reactive
tissue.2
Symptoms and clinical findings are
deter-mined by the rate of growth and position
of the cyst. These findings are on a
mechani-cal basis and are caused by the extrinsic
pressure of the mass. The slower growing
cysts are the best tolerated. The host may become sensitized to the foreign protein of
the hydatid cyst. Rupture or leakage can
cause generalized anaphylactic reaction.
Rupture can also seed the pulmonary
par-enchyma with secondary cysts, cause
he-moptysis, or a pneumothonax.3 On occasion
spontaneous cure may result from complete
evacuation of the cyst by rupture into a
bronchus.4
CASE REPORT
J. A. is a 10-year-old white male who was first seen in the Outpatient Clinic of the Kimbrough
Army Hospital on September 11, 1963. FIe corn-plained of dull chest pain of 10 days’ duration. The patient stated that he was accidentally kicked
in the left hemithorax by another child
approxi-mately two weeks prior to the onset of chest pain.
The pain was mild and was localized to the left hemithorax, was not related to coughing, deep
breathing, or position. The patient had a poor
appetite and had small weight loss and low-grade fever over a 3-week period.
Positive physical findings on initial examination
were limited to the chest. There was slight dullness to percussion with diminished vocal fremitus and
diminished breath sounds and auscultation in the
left lung base posteriorly.
Apparent elevation of the left hemidiaphragm in
700 PULMONARY CYST
th( chest (Fig. 1, A and B). There was some
pleural reaction at the left base and the spleen
appeared normal. On fluoroscopv the posterior portion of the left hernidiaphragm was thought to be elevated and both heniidiaphragms moved with respiration; however, the posterior portion of the
left hemidiaphragm had slight decreased
excur-sions. Initially the density in the posterior portion
of the chest was thought to be pleural fluid and reaction, probably secondary to the patient’s trauma, with the possibilit of a congenital defect of the diaphragm being considered.
The past medical history of the patient was
non-contributory. The patient had a tonsillectomy and adenoidectornv procedure in jul, 1957, at another hospital. The preoperative chest roentgenograms
were reported as negative. These films were not available for interpretation. Because of the clinical
picture and the slow progressive course, a viral pneumonitis was considered as the etiology of the chest (lensitV. The PPD and histoplasmin skin
t(stS were negative. The CBC revealed a hemo-globin of 1 1 .4 gm and hematocrit of 36, with a
white blood count of 16,800 with a normal dif-ferential. The sedimentation rate was 44 mm
Un-corrected, corrected to 36 mm.
The patient remained relatively asvmptomatic. After a 3-week interval the chest roentgenograms were repeated (Fig. 2, A and B). On this
examina-tion there was a homogeneous density in the left
posterior lung field and there was an extension of
a radiopaque density throughout the lower lung
field anteriorly’. This was thought to represent a
superimposed pleural effusion. Eleven days later
the mass measured 10 cm in diameter. The
an-tenor pleural effusion was completely resolved and there was a semicircular, crescent-shaped radio-lucency in the apex of the mass, which did not change in shape in the decubitus position (Fig. 3, A and B). The following diagnostic possibilities were then considered : an organizing hematoma, a congenital pleural sequestration with recent super-imposed infection, a congenital or posttraumatic
herniation of a solid viscus through the posterior
diaphragm, an organizing fibrin ball secondary to granulomatous or fungus disease, or the possibilit of a parasitic cyst such as Echinococcus cyst. Since roentgenograms taken in 1957 were reported as
normal, the congenital lesions were not strongly
considered.
The patient lived in Iran for two years, from
1957 to 1959. He also owned a dog that was in
close contact with sheep and cattle.
On October 21, 1963, the patient was admitted to the hospital for further evaluation. His clinical findings were unchanged. A complete laboratory work-up was essentially non-contributory. Comple-ment fixation tests for histoplasmosis, blastomscosis, and coccidioidomycosis were negative. A Casoni skin test and complement fixation tests for
Echinococcus were also negative.
A B
FIG. 1 (A). A large homogeneous mass of tissue density is noted filling the left lower hemithorax in the posterior-anterior projection of the chest. The superior border of this density is smooth and regular,
sug-gesting that this is a portion of the left hemidiaphragm. (B) In the lateral projection the density’ is seen posteriorl and involves the posterior costophrenic sulcus. There is slight pleural thickening along the
701
A B
Fic. 2 (A). There is little change in the radiographic appearance of the chest in the repeat posterior-anterior view. The homogeneous densit is again seen and appears somewhat more confluent and in-creased in density since the initial examination. (B) In the lateral projection the density is seen to extend across the entire left hemithorax which is secondary to a superimposed pleural effusion as well as the
posterior mass.
These investigations were done under direction
of Dr. Irving G. Kaggan, Chief, Parasitolog Unit, Mycology and Parasitology Section, U.S.P.H.S., Communicable Diseases Center, Atlanta. He writes:
“The antigen for the Casoni test is a new antigen and our method has not been published. It is an
extract of Echinococcus multilocularis which has
been under evaluation in Urugua’ for the past year and found to be very satisfactory for hydatid disease due to Echinococcus granulosus. This ex-tract contains 12 gamma of N/mi.”
An increase in the density of the left lower lobe with a crescent sign was seen on repeated chest roentgenograms taken on hospital admission (Fig. 3, A and B). An air-fluid level was seen 10 (lays
later on October 31, 1963. An upper CI series was
normal. Two attempts at bronchoscopy and
bron-chographv were unsuccessful due to laryngeal
sPasm.
The clinical course was uneventful except for a fever up to 102#{176}F (38.9#{176}C) of 3 day’s duration following the attempted bronchoscopy. This
sub-sided with srnptomatic treatment.
The patient had a left thoracotomy on November
12, 1963, and a left lower lobe lobectonw was
performed. A solitary Echinococcus cyst, 5 7 cm
in diameter, was removed intact along with the
left lower lobe. The patient tolerated the
pro-cedure well and had an uneventful recovery. The
clinical specimen was sent to the Pathology labora-tory and multiple scolices and hydatid sand were
identified within the fluid confirming the
preopera-tive diagnosis of Echinococcus cyst. He was
dis-charged on December 19, 1963, to be followed in
the Outpatient Clinic. A postoperative liver scan on
Januarv 10, 1964, was negative and revealed no mass lesions within the liver. The patient’s sister had a chest roentgenogram, a Casoni skin test, comple-ment fixation test, and a CBC, which were all
within normal limits.
COMMENT
Hydatid disease is twice as common in
males as in females. This is probably see-ondary to the habits of boys which increases
their exposure to the source of infection,
usually a pet dog. Hydatid disease is usually seen in the first three decades of
life with the majority of cases within the
second decade. In the presented case, the
patient’s age and sex placed him in the
702 PULMONARY CYST
disease. The Casoni reaction may be
posi-tive in as few as 50% of the cases, and
eosinophiiia may or may not be present.
Eosinophuiia is prevalent when there has
been rupture of tile cyst. The chest
roent-genograms were characteristic in
appear-ance in that there was a solitary pulmonary
mass which developed a nadiolucent
cres-cent-silaped air space on repeated
examina-tions. This radiolucency does not represent
an air-fluid level, but rather a retraction of
the ectocyst from the pericyst. Pleural
effu-sion can accompany this disease but its
presence or absence is not of diagnostic
significance.
The liver is the most frequent site of
involvement by hydatid cysts in most of
the adult series reported in the literature.
In tile pediatric age group, pulmonary
hy-datid disease is as frequent and may be
even more frequent than the hepatic form.
In a series of 72 cases from the Royal
Chil-drens Hospital of Melbourne, Australia, 36
cases were pulmonary, 18 were hepatic, and
9 were combined hepatic and pulmonary.
Of 98 pediatric cases from the Royal
Alex-andria Hospital for Cilildren in Sydney, 45
were pulmonary and 46 hepatic. Hydatid
cysts of the lung are usually located in the
basilar segments. This is probably
second-any to venous or lymphatic spread rather
than direct inhalation of the hydatid
scolices.
In the presented case, the rate of growth
was more rapid than usual. The patient had
no allergic manifestations in spite of the
possible partial rupture or leakage of the cyst. Eosinophilia was absent on repeated
CBC’s and the Casoni skin test and
corn-plement fixation were negative.
Radiographically any homogeneous
pul-monary density, spherical or ovoid in shape,
max’ represent a pulmonary hydatid cyst.
While this is an infrequent diagnostic pos-sibiiitv in this country, it should not be overlooked. Retraction of the penicyst from
A B
FIG. 3 (A). A semilunar radiolucency is seen in the superior portion of the homogeneous density in the
repeat posterior-anterior examination of the chest. This represents a retraction of the pericyst from the
ectocyst. This semilunar appearance is characteristic of a hydatid cyst. (B) The semilunar radiolucencv
ARTICLES
the ectocyst may cause a crescent sign, a partial rupture or leakage of the contents
of the cyst will present as a cavity with an
air-fluid level. On occasion an irregularity
can be observed within the fluid which has
a flower-like appearance, representing the retraction of the cyst membranes. This is
the so-called “lily” sign, and was the only
radiographic sign not observed in the
pre-sented case.6
The diagnosis of this entity is not difficult
if it is kept in mind. The history of animal
contact combined with the clinical picture,
laboratory work-up, and the roentgenologic
signs are the most important points for
cor-rect diagnosis. Penicutaneous aspiration
biopsy of the cyst should be avoided since
seeding of daughter cysts is likely and an
anaphylactic reaction may occur if the cyst
fluid enters the pleural cavity or pulmonary
parenchyma. The treatment is surgical.
Enu-cleation, segmental resection,
marsupializa-tion, or lobectomy are all advocated
de-pending upon the location of the cyst and!
or experience of the surgeon.7 Preventive
health measures are necessary for
eradica-tion of this disease in endemic areas.
SUMMARY
A case of solitary Echinococcus cyst of
the lung was presented. The diagnosis can
be suspected from the clinical history which
should include animal contact. The
pre-sented patient had been in an endemic area;
however, cases can occur in individuals who
have never left the United States. This
pa-tient had a solitary pulmonary mass. The
mass grew in size under observation with a
pleural effusion which cleared
spontaneous-ly. The laboratory work-up was completely negative including lack of eosinophilia
and a negative Casoni and complement
fixation test. The semilunar air shadow
within the mass suggested the preoperative
diagnosis of Echinococcus cyst of the lung.
If the diagnosis is considered, it is possible
that it may be established preoperatively
with increasing frequency.
REFERENCES
1. Brooks, T. J., Webb, W. R., and Heard, K. M.:
Hydatid disease: A summary of human cases
in Mississippi. Arch. Intern Med., 104:561, 1954.
2. Schiler, E. L. : Echinococcosis in North
Amer-ica. Ann. Intern. Med., 52:464, 1960.
3. Tomalino, D. : Complicaciones Pleurales de Ia Hidatidosis. Torax, 8 :73, 1959.
4. Venkateswara Rao, R. : X-ray diagnosis of
hy-datid cyst of the lung: Its rupture into the
bronchus and spontaneous healing. J. Indian.
Med. Ass., 34:353, 1960.
5. Myers, N. A. : Hydatid disease in a childrens hospital. Med. J. Aust., 47:806, 1960.
6. Swinburn, P. : Pulmonary hydatid disease. New Zeal. Med.
J.,
61:481, 1962.7. Barrett, N. R.: The anatomy and the pathology of multiple hydatid cysts in the thorax. Ann.
