Ann Thorac Surg 2001;71:1338-1341
© 2001 The Society of Thoracic Surgeons
Case report
Dysphagia caused by a fetus-in-fetu in a 27-year-old man
Malek G. Massad, MDa,
Lawrence Kong, MDa,
Enrico Benedetti, MDa,
Daniel Resnick, MDa,
Luna Ghosh, MDb,
Alexander S. Geha, MDa,
Herand Abcarian, MDa
a Department of Surgery, The University of Illinois at Chicago, Chicago, Illinois, USA
b Department of Pathology, The University of Illinois at Chicago, Chicago, Illinois, USA
Accepted for publication May 14, 2000.
Address reprint requests to Dr Massad, Division of Cardiothoracic Surgery (M/C 958), The University of Illinois at Chicago, 840 S Wood St CSB, Suite 417, Chicago, IL 60612
e-mail: mmassad{at}uic.edu
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Abstract
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Mechanical obstruction of the distal esophagus by a fetus-in-fetu is an extremely rare condition that has not been previously reported. We present the case of a 27-year-old man who presented with dysphagia caused by fetus-in-fetu contained within a retroperitoneal cystic cavity. The tumor, noticed since childhood, did not cause any symptoms until a year before presentation when symptoms of dysphagia developed. We propose including this entity in the differential diagnosis of a retroperitoneal mass.
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Introduction
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Fetus-in-fetu is a term coined by Meckel (circa 1800) describing a parasitic twin included within the abdomen of its partner as a result of an embryonal developmental aberration [1]. In this article, we present the case of a 27-year-old man, the oldest reported with a fetus-in-fetu, who presented with dysphagia due to extrinsic compression of the distal esophagus by the mass.
A 27-year-old Hispanic man was referred to our institution on October 26, 1997 with complaints of dysphagia to solid foods, weight loss (10 lbs over the past 2 months), cough, and right upper abdominal fullness. The patient is married with two children. He has a history of familial twinning (first cousins) but no other significant family history. He was born in a small hospital in Mexico and has not seen a physician since. He reported noting an upper abdominal fullness since childhood but sought no medical attention because of absence of related symptoms. Since then, the mass has been steadily growing. He has no history of jaundice. On clinical examination, the patient appeared thin but well nourished and healthy. His vital signs were normal. Chest auscultation demonstrated diminished breath sounds in the lower chest. A large, round firm and fixed right upper abdominal mass was present on examination extending over the midline. The liver could not be palpated. Bowel sounds and rectal examination were normal. Laboratory evaluation included serum amylase and lipase levels, serum creatinine, blood urea nitrogen (BUN) and liver function tests, all of which were normal. Serum ß-human chorionic gonadotropin, 
-fetoprotein and carcinoembryonic antigen levels were also normal.
Plain chest and abdominal radiography (Fig 1) were obtained and showed a retrocardiac mass with elevation of the right hemidiaphragm and superior displacement and splaying of the carina. An ossified density contained in a cavity with a calcific rim was noted in the right upper quadrant. The ossified density had the shape of a mandible with four distinct molar teeth. In view of the dysphagia, an upper gastrointestinal series was performed and that showed a narrowed, anteriorly and laterally displaced distal esophagus and stomach (Fig 2). Computer tomography (CT) scan of the chest and abdomen showed a large ovoid complex structure with rim calcifications measuring 22x18x14 cm located in the upper retroperitoneal space. The mass extended to the posterior mediastinum causing compression and stretching of the right inferior pulmonary vein and superior displacement of the anterior mediastinal structures. There were multiple densities contained within the mass representing fat, fluid, and soft tissue with a large area of calcification (Fig 3). Multiple round calcified pleural nodules were also seen on CT scan. Celiac and mesenteric angiography showed patent celiac, superior mesenteric and bilateral renal arteries. A branch of the right inferior adrenal artery appeared to be feeding the mass. Delayed images showed a displaced but patent porta hepatis. Vena cavogram showed patent but laterally displaced and compressed inferior vena cava and dilated azygous and hemiazygos veins.
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Fig 1. Plain radiogram of the chest and abdomen shows a retrocardiac mass with elevation of the right hemidiaphragm and superior displacement and effacement of the carina. An ossified density, the shape of a mandible with four distinct molar teeth contained within a cavity with a calcific rim, was noted in the right upper quadrant.
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Fig 2. An upper gastrointestinal series shows a narrowed, laterally displaced distal esophagus and stomach with narrowing at the gastroesophageal junction.
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Fig 3. CT scan of the abdomen shows a large upper retroperitoneal mass measuring 22x18x14 with calcified rim. Multiple densities within the mass represent fat, fluid, soft tissue and bone.
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The diagnoses of benign cystic teratoma or a teratocarcinoma were contemplated. Because of the presence of the pleural-based nodules on the chest CT scan and the ill-defined relation of the mass to the heart and pulmonary veins, a decision was made to obtain a tissue diagnosis through video assisted thoracoscopy (VATS). Multiple transpleural biopsies of the subpleural based nodules failed to show evidence of malignancy. The nodules consisted of fatty tissue contained within calcified round structures that appeared to be due to rupture of the retroperitoneal mass contents with pleural seeding. With the presumptive diagnosis of a retroperitoneal teratoma, a decision to explore the right chest was made in order to: (1) establish a diagnosis that may determine a role for preoperative chemotherapy in the case it was malignant, (2) determine the resectability of the tumor in the chest, and (3) avoid leakage of the fluid contents of the tumor into the abdominal cavity after biopsy. Right chest exploration was performed through the sixth intercostal space. The posterior mediastinum was found to be frozen and immobile. The abdominal mass caused upward displacement of the right hemidiaphragm which was intimately adherent to the posterior mediastinum and the right lower lobe of the lung. Multiple biopsies and aspirates of sebaceous material from the mass through the diaphragm were made. The patient recovered without incident but the final pathology offered no definitive diagnosis (inflammatory reaction).
Two days later, the patient underwent an exploratory laporatomy through a xypho-pubic midline incision. At laporatomy, a large well-circumscribed cystic retroperitoneal mass was present. The mass was bordered superiorly by the diaphragm and left lobe of the liver; anteriorly by the anterior abdominal wall; inferiorly by the hepatic pedicle, duodenum and pancreas, medially by the lesser curvature of the stomach and gastroesophageal junction, and laterally by the liver. Because the cyst was deeply adherent to the left and caudate lobes of the liver, it was opened and the contents were drained and removed. About 500 mL of thick sebaceous fluid was first removed followed by an abundant amount of thick hair and a fetal-like structure covered with sebum. The cyst wall was then excised preserving the inferior vena cava. The retrohepatic space was drained with a single Jackson-Pratt drain. The postoperative course was uneventful and the patient was discharged home on the sixth postoperative day. The symptoms of dysphagia have disappeared immediately after the operation. He started to gain weight and continues to do well at two-year follow-up.
Gross examination of the sac showed a thin walled membrane filled with sebaceous material and hair. Contained within that sac was a structure with fetal-like features, 14 cm long, weighing 754 g covered with thick wrinkled skin and appendages (Fig 4). The fetal-like structure had a cranium with an eye socket, mandible and four molar teeth. There were superior limb buds consisting of a right upper limb and a left digit with pointed nails. The lower part contained two lower limb buds with foot-like projections with five buds and long pointed nails. Histologic sections of the cyst wall showed fibrocollagenous tissue with chronic inflammation. Histologic sections of the specimen showed evidence of a cranium, retinal tissue within an eye socket, mandible with 4 teeth, an axial skeleton with cervical vertebrae and long bones and respiratory buds. Specimen radiography confirmed the presence of a rudimentary spinal column with vertebra and a bony pelvis. Each lower limb bud had a primitive femur, tibia, foot and phalanges. Genetic studies included chromosome analysis performed on fibroblasts cultured from the fetus and on leukocytes from the patient. Both subjects had a normal male karyotype (46, XY). There was no evidence of mosaicism or any structural or numerical abnormalities. Of interest was the absence of inversions in chromosome 12p frequently seen in patients with teratoma.
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Comment
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Fetus-in-fetu represents an abnormality in the twinning process where the aborted or suppressed monozygotic twin develops partial or complete external morphologic characteristics of a human form. The growth of a fetus-in-fetu initially parallels its twin in utero but then abruptly stops due to vascular dominance of the host twin or to an inherent defect in the parasitic twin [2]. It is important to differentiate these extremely rare cases from the much more frequent, highly organized, well-differentiated, teratoma which is a true tumor with a distinct malignant potential. The distinction of these two entities has been a source of controversy [1, 3, 4]. Whereas a teratoma is composed of one or more of the three primary embryonic germ layers in a discordant fashion and lack primary organization, a true fetus-in-fetu contains a vertebral column and demonstrates a high degree of structural organization. Willis reasoned that development of a vertebral column or neural tube indicates fetal development through the primitive streak stage and the beginning of organoaxial orientation [5]. Gross referred to 39 cases of fetus-in-fetu with equal sex distribution and suggested a different pattern from sacrococcygeal teratomas in which females outnumber males by a ratio of four to one [6]. Twenty-five of these cases (64%) occurred in patients less than two years of age.
Lord set forth more stringent criteria noting that all fetus-in-fetu are located in the retroperitoneum, and have an appropriate arrangement of organs and limbs with respect to the vertebral column [7]. Of the 11 cases he reviewed, only four conclusively met the criteria for fetus-in-fetu [4]. Quimet presented a sacrococcygeal teratoma with two limb buds but no vertebral column and questioned if this attempt at axial formation constitutes a diagnosis of fetus-in-fetu [4]. de Lagausie and coworkers reported a "pseudofetu" or a sacrococcygeal teratoma with no vertebral column but contained a rudimentary single-cavity heart beating at a rate slower than that of the host along with a well developed digestive tract and presence of amniotic fluid [3]. He surmised that presence of nerve tissue in the bowel wall and melanocytes in the skin implied the existence of a notochord. However, because of defective vascularization, a vertebral column never developed. He suggested that the two entities may overlap or even represent the same pathology at different stages of maturation. Lewis confirmed the existence of borderline cases where a clear distinction cannot be made [1].
There have been only four documented cased of fetus-in-fetu occurring later in life. Two were teenagers, 15 and 17 years old, described by Lord [7]. The third case was quoted by Grosfeld and coworkers [8] from a newspaper article describing a fully formed fetus found during an autopsy in the abdomen of an aged human killed in an automobile accident. The fourth was reported by Dagradi and coworkers [2] who removed a fetus-in-fetu possessing vertebrae, ribs, tibia, and iliac bones from a 47-year-old human. The present case meets all the clinical criteria of a fetus-in-fetu that were described previously [1, 9, 10] and, to the best of our knowledge, is the first case of a fetus-in-fetu in an adult male to cause dysphagia.
The treatment of choice for a fetus-in-fetu is operative excision with the surrounding sac in order: (1) to avoid the potential effects of continued compression on surrounding structures, (2) to eliminate the chance of infection, bleeding and pleuroperitoneal inflammation caused by leak of the sac contents, and (3) to exclude malignant potential in the wall of the mature teratoma in borderline cases where the distinction between the latter and a fetus-in-fetu is unclear. We propose including this entity in the differential diagnosis of a retroperitoneal mass.
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References
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Lewis R.H. Fetus-in-fetu and the retroperitoneal teratoma. Arch Dis Child 1961;36:220-226.[Medline]
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Dagradi A.D., Mangiante G.L., Serio G.E., Musajo F.G., et al. Fetus-in-fetu removal in a 47-year-old man. Surgery 1992;112:598-601.[Medline]
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De Lagausie P., de Napoli-Cocci S., Stempfle N., et al. Highly differentiated teratoma and fetus-in-fetu: a single pathology?. J Ped Surg 1997;32:115-116.[Medline]
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Quimet A., Russo P. Fetus-in-fetu or not?. J Ped Surg 1989;24:926-927.[Medline]
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Willis R.A. The border land of embryology and pathology, 2nd ed. London: Buttersworths, 1962:442-462.
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Gross R.E., Clatworthy H.W., Jr Twin fetuses-in-fetu. J Pediatr 1952;38:502-508.
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Lord J.M. Intra-abdominal fetus-in-fetu. J Path Bact 1956;72:627-641.
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Grosfeld J.L., Stepita D.S., Nance W.E., Palmer C.G. Fetus-in-fetu: an unusual cause for abdominal mass in infancy. Ann Surg 1974;180:80-84.[Medline]
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Janovski N.A. Fetus-in-fetu. J Ped 1962;61:100-104.[Medline]
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Farris J.M., Bishop R.C. Surgical aspects of abnormal twinning. Surgery 1950;28:443-453.[Medline]
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Abstract
Introduction
