Fetus-in-fetu: Report of a Case
JE G. CHI, M.D., YOON S. LEE, M.D., YOUNG SIK PARK, M.D., AND KA YONG CHANG, M.D.
Departments of Pathology and Anatomy, College of
Medicine, Seoul National University and Department of
Pediatric Surgery, Christian Children's Hospital, Pusan
A case of fetus-in-fetu is reported. It occurred in an 8-week-old
Korean boy who had been born by cesarean section due to abdominal distension. The fetus-in-fetu was connected to the superior mesenteric artery and consisted of two masses, apparently
representing two portions of an acardiac monster. There was an
amniotic membrane covering both masses, and the umbilical
cord clearly was identifiable. One mass included the brain, eye,
trachea, salivary glands, thyroid, pancreas, spleen, etc., while
the other mass contained extremity bones, vertebrae, testis, adrenals, and intestinal loops. This is probably a case of separated
fetus-in-fetu that showed unusually well-developed internal organs. (Key words: Fetus-in-fetu; Acardiac twin; Retroperitoneal
teratoma) Am J Clin Pathol 1984; 82: 115-119
FETUS-IN-FETU is a rare congenital abnormality that
results from embryonic duplication or twinning. Today
it is generally accepted that the distinction between fetusin-fetu and teratoma is largely determined by whether an
axial skeletal system is present. Because the presence of
the vertebra indicates that the mass has passed through
the primitive streak stage and developed in the manner
of fetal development. In addition to the vertebra, the
fetus-in-fetu possesses its own amniotic membrane with
a vascular connection usually to the mesenteric vessels
of the host. Retroperitoneal location with well-developed
extremities, organ systems, and invariable benignity of
this lesion sharply contradict mature teratoma.
We report a fetus-in-fetu in an 8-week-old Korean boy,
in regards to its rarity and interest in its morphogenesis.
Report of a Case
A Korean boy, aged 8 weeks, was admitted to the Pusan Christian
Children's Hospital, because of a progressive abdominal distension. Being
a large baby, he was born by a cesarean section. The birth weight was
4 kg. The baby was found to have abdominal distension at the time of
birth. The abdominal distension became more and more severe for a
period of four weeks, and then the patient suffered from episodic vomiting
and dyspnea.
At the time of admission, physical examination showed a large cystic
massfillingnearly all of the abdominal cavity. A simple radiograph of
the abdomen showed the densities of femur, tibia, and pelvic bones.
Routine laboratory examinations remained within normal limits. On
operation, the cystic mass, originating from the upper retroperitoneum,
Received September 12, 1983; received revised manuscript and accepted for publication December 14, 1983.
Address reprint requests to Dr. Chi: Department of Pathology, College
of Medicine, Seoul National University, 28 YunKun-Dong, ChongroKu, Seoul 110, Korea.
was found to displace the stomach and transverse colon upward and
loops of small intestinal toward the pelvic cavity. To facilitate removal,
approximately 2 L serous straw-colored fluid was aspirated through a
semitranslucent membrane covering the mass. The tumor mass consisted
of two parts that were floating inside the cyst. The cystic membrane
was easily separated from the surrounding organs except for an area
where the superior mesenteric artery was feeding the two masses through
a slender cord. The mass was removed entirely.
Pathologic Examination. The mass weighed 650 g and was enveloped
by a semitranslucent amnion-like membrane that stretched out to the
umbilical cord of the "fetus" (Fig. 1). The membrane was lined, microscopically, by amnion and metaplastic squamous epithelium resting
onfibrocollagenoustissue. The included fetus consisted of two masses
connected by a thin membrane. A small vessel was found inside the
membrane.
Of the two masses, the one with an umbilical cord, designated as
"A," had features of an acardius acephalus. The structures of the lower
half of the body were seen, ie., protruded umbilicus, two lower extremities,
pelvic bones, and vertebrae (Fig. 2). The entire mass was covered by
edematous skin. The skeletal system of the extremities were complete,
including normally formed joints.
The connecting stalk resembling an umbilical cord was lined by attenuated stratified squamous epithelium. This cord epithelium was continuous to that of amniotic membrane that covered the mass. This stalk
contained several loops of bowel. Sections from the bowel loops showed
various types of mucosa such as jejunum, ileum, and colon. Between
circular and longitudinal layers of smooth muscle, an adequate number
of myenteric plexus with ganglion cells was found. Serosa was clearly
visible, though the mesentery was not observed.
The vertebra, above the two lower extremities, was composed of a
column of segmented cartilages and trabecular bones (Figs. 7>A and B).
There were four lumbar and two sacral vertebral bodies. Bone marrow
showed active hematopoiesis. Beside the vertebra, several sympathetic
ganglia and a large trunk of peripheral nerve, probably sciatic nerve,
was found. A small cystic dilatation of the upper dorsal portion of the
mass was seen and appeared to be a meningocele. "Pelvic cavity" was
composed largely of mature fat, skeletal muscle, and fibrocollagneous
tissue. Two adrenal glands and two testes were indentified. The adrenal
cortex showed a pattern of a permanent cortex with prominent zona
fasciculata, and the medulla consisted of a few nests of chromaffin cells
around vessels. The testes were well developed, corresponding in histology
to that of early infancy (Fig. 4). No structure of urinary system was
found.
The mass "B," connected with "A" by a thin membrane originating
at the vicinity of the umbilical cord, was lobulated irregularly. Mass
"B" had an external appearance of acardius amorphus (Fig. 5). It was
covered partly by hairy skin and consisted of cerebrum and choroid
plexus above an irregular bony mass resembling skull base. Also retinal
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FIG. 1 (upper, left). Two masses are connected with a linear fibrous tissue and enveloped by a membranous tissue.
The left one, "A," two legs and a lower trunk. Right, "B," is a multilobular amorphous mass.
FIG. 2 (lower, left). Specimen radiograph shows well-formed skeletal system, particularly of the lower extremities.
FIG. 3. A (upper, right). Represents cut surface of the mass "A" showing an adrenal gland (A) and a testis (T),
along with vertebral bones (V). B (lower, right). Represents the radiograph disclosing vertebrae and pelvic bones.
<
pigments, paranasal sinuses, salivary glands, thyroid, parathyroid, pancreas, lymph nodes, and trachea were found (Fig. 4). The cerebral tissue
was covered by scalp and meninges, but not by calvarium. The brain
showed partial but definite cortical development and was of rich vasculature. Six-layered cortex and white matter were clearly visible. However, the ventricular system was not seen. The salivary glands and thyroid
were of fetal type. The trachea had cartilage rings and mucous glands.
No pulmonary tissue was present. The pancreas showed numerous acini,
islands of Langerhans, and dilated intercalate ducts. No signs of the
heart, liver, spleen, and upper gastrointestinal tract were found. Since
the specimen wasfixedimmediately in formalin chromosome study of
this mass could not be performed.
Postoperatively the patient (host) did very well. As of the time of this
case report he is healthy without evidence of disease.
Discussion
There is a general agreement that the fetus-in-fetu originates from an anomalous inclusion of monozygotic twins
as a consequence of the anastomosis of the vitelline circulation,6 and therefore is distinguished from mature teratoma in many ways.
Since Lord10 described 11 cases of fetus-in-fetu after
reviewing 42 alleged cases, sporadic cases were found in
the literatures.1"7'9" Of those cases, 20 cases were available
for review. Fourteen fetus-in-fetu out of 20 manifested
themselves during infancy of the host (autosite), three in
the second year of age and the other three additional ones
at 9, 15'/2, and 17 years, respectively. The last one, however, had been present since three months of age.3 There
seems to be no indication of any particular sex incidence
in fetus-in-fetu. Ten were from boys and eight from girls,
while two had no comment on their sex.
Because the fetus-in-fetu has a close relationship with
anastomosis of the vitelline circulation, the usual site of
occurrence is the abdominal cavity. In fact, most cases
in the literature report the location of the fetus at upper
retroperitoneum. Kakijoe and Tahara, however, described
a fetus-in-fetu in the scrotal sac of a full-term Japanese
infant.7 This unusual location suggests migration of the
fetus from the retroperitoneal cavity along with the normal
descent of the testis to the scrotal sac via tunica vaginalis.
The other extraordinary location reported by Kimmel
and associates was a cranial cavity that contained five
fetal masses.8 However, because of the absence of developed axial skeletal, their findings are open to question.
The fetus gets its blood supply from the host. The
feeding vessels commonly were connected to the superior
mesenteric vessels. Otherwise, the kidney, liver, or aorta
itself were reported to feed the fetus.
Besides the vertebra, commonly found in fetus-in-fetu
are dermal structures, extremities, gastrointestinal tract,
and the central nervous system. Less commonly found
are the gonad, adrenal gland, heart, and the primitive
respiratory unit. The pancreas and spleen were demonstrated in the case of Grosfeld and associates.4
The fact that the fetus-in-fetu in our case was divided
into two separate masses connected only by a thin feeding
vessel led us to speculate whether these two masses are
two separate fetuses or a separated single fetus.
Taylor's report in Lord's series demonstrated a trilobed
appearance because of deep grooves.10 Grosfeld and associates reported a bilobed one. 4 Gross and Clatworthy
presented two fetus-in-fetu, which were connected by an
umbilical cord.5 In our case the fetus-in-fetu was divided
completely into two parts; one represented acardius
acephalus and the other the acardius amorphus. The organs of the two masses did not overlap each other, representing upper and lower portions of the body. Therefore,
it would be reasonable to assume that in this case a single
fetus was divided into two parts during the development
of the fetus-in-fetu. This kind of separated fetus-in-fetu
could not be seen in previous reports.
The most striking anomaly in this case would be the
absence of the heart. The acardiac fetus always must be
associated with a normal twin to survive. Acardiac twins
get the blood supply from the heart of its partner and is
almost always accompanied by defective organogenesis.
Acardius acephalus is characterized by the development
of the lower limbs and pelvis. While acardius amorphus
represents a shapeless mass of connective tissue, bone,
and visceral organs covered by skin. Yoshihara and Maisel
explain the acardius by saying that the endocardial tubes
are formed, fused in the midline but further cardiac morphogenesis failed, while the pharyngeal arch system and
formation of large vessels were initiated appropriately
during development.12 When there is an anastomosis of
the umbilical vessel system, the heart of the normal twins
becomes the driving force for the circulation of blood of
both twins, and the heart of acardius fails to be differ-
FlG. 4. Photomicrographs of various parts of the specimen. A {upper, left) epididymis and testis; B {upper, right) cartilage ring surrounded by
mucous glands and bundles of skeletal muscle, indicative of a trachea; C {lower, left) pancreatic acini and ductules in lobular pattern; and D {lower,
right) adrenal gland showing adult type cortex without fetal zone.
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CASE REPORT
119
FIG. 5. Mass "B" consists of multiple cystic spaces and brain tissue.
entiated and would undergo secondary atrophy. This fact
may indicate that fetus-in-fetu is actually a kind of an
included heteropagus with acardius.
References
1. Broghammer BJ, Wolf RS, Geppert CH: The included twin or fetus
in fetu; A case report. Radiology 1963; 80:844-846
2. Fujikura T, Hunter WC: Retroperitoneal fetus in fetu. Obstet Gynecol 1959; 13:547-554
3. Galatius-Jensen F, Rah DH, Uhm IK, Thorborg J: Foetus in foetu.
Br J Radiol 1965; 38:305-308
4. Grosfeld JL, Stepita DS, Nance WE, Palmer CG: Fetus-in-fetu:
Unusual cause for abdominal mass in infancy. Ann Surg 1974;
180:80-84
5. Gross RE, Clatworthy HW: Twin fetuses in fetu. J Pediatr 1951;
38:502-508
6. Janovski NA: Fetus in fetu. J Pediatr 1962; 61:100-104
7. Kakijoe T, Tahara M: Fetus in fetu located in the scrotal sac of a
new born infant; a case report. J Urol 1972; 107:506-508
8. Kimmel DL, Mpyel EK, Peale AR, Winborne LW, Gotwals JE: A
cerebral tumor containing five human fetuses; case of fetus in
fetu. Anat Rec 1950; 106:141-165
9. Lewis RH: Foetus in foetu and the retroperitoneal teratoma. Arch
Dis Child 1961;36:220-226
10. Lord JM: Intra-abdominal foetus in foetu. J Pathol Bacteriol 1956;
72:627-64)
n Tada S, Yasukochi H, Ohtaki C, Fukuta A, Takanashi R: Fetus in
fetu. Br J Radiol 1974; 47:146-148
12 Yoshihara H, Maisel H: An acardiac human fetus. Anat Rec 1973;
177:209-218
Disseminated Intravascular Coagulation in Two Patients with
Histiocytic Medullary Reticulosis
DINA SALZ-STEINER, M.D., AMIRAM ELDOR, M.D., DOV VANGROVER, MD., ELIMELECH OKON, M.D.,
ELDAD BEN-CHETRIT, M.D., ELIEZER A. RACHMILEWITZ, M.D., AND AARON POLLIACK, M.D.
Two young adults with characteristic features of histiocytic
medullary reticulosis (HMR) are described. Of particular interest
was the development of striking clinical and laboratory features
of disseminated intravascular coagulation (DIC), in the absence
of sepsis in both cases. Both patients had a marked and fatal
bleeding tendency. The association between neoplasia and DIC
is well established, but, to the best of our knowledge, DIC presenting a major feature of HMR has not yet been described.
Received September 26, 1983; received revised manuscript and accepted for publication December 8, 1983.
Address reprint requests to: Dr. D. Salz-Steiner: Department of Hematology, Hadassah University Hospital, P.O. Box 12000, Jerusalem,
Israel 91120.
Departments of Hematology, Medicine B, Pathology and
Medicine A, Hadassah University Hospital, Jerusalem, Israel
The possible pathogenesis of DIC in HMR is discussed. (Key
words: Histiocytic medullary reticulosis; Malignant histiocytosis;
Disseminated intravascular coagulation.) Am J Clin Pathol 1984;
82: 119-123
MALIGNANT HISTIOCYTOSIS (histiocytic medullary
reticulosis—HMR) is a rare disorder characterized by
histiocytic infiltration of organs abundant in reticuloendothelial components." 1 2 The intense proliferation of