Truncal duplication: a case report

Pediatr Surg Int (1998) 14: 227±228

Ó Springer-Verlag 1998

CASE REPORT

_ Karaca á C. GuÈnsar á B. Etensel E. Mir á A. Sencan á I.

Truncal duplication: a case report

Accepted: 22 January 1998

Abstract Truncal duplication represents one of the rare forms of conjoined twins. We observed a male infant with a truncal duplication; in the host twin no pathology was found except an atrial septal defect and a large omphalocele. The parasitic twin was attached to the xiphoid region (xiphopagus) in an opposite and ``horseriding'' manner, was acephalic, and had multiple gastrointestinal, genitourinary, and skeletal anomalies. The junction site consisted of lipoid and muscular structures. Surgical separation was done without any diculty. The abdominal defect was repaired primarily. The host twin is doing well. Key words Conjoined twins á Truncal duplication á Parasitic twin á Xiphopagus

Introduction Conjoined twins represents one of the rarest congenital anomalies [4, 5]. It may be considered a form of duplication or a doubling anomaly, and may range from complete to incomplete duplication of an individual [5]. An inadequately developed conjoined twin is termed a

_ Karaca á A. Sencan (&) á E. Mir á I. C. GuÈnsar á B. Etensel Department of Pediatric Surgery, Izmir Children's Hospital, Alsancak, Izmir, Turkey

parasitic twin [7]. Although many cases of caudal duplication have been reported in the literature, there was only one case of a truncal duplication [1, 8]. We report a case of truncal duplication in which the parasitic twin was attached in the xiphoid region.

Case report A male infant weighing 4.45 kg was born to a gravida III, parn II mother in the 40th week of gestation via the vaginal route. He was transferred to our department on the 1st day of life. There were no complications during the pregnancy. There was no family history of congential abnormalities or consanguinity; one grandmother was diabetic. Clinical examination of the host twin showed cyanosis, tachypnea, and subconjunctival hemorrhages thought to be related to a traumatic delivery. The heart rate ranged between 130 and 160 beats/ min, the blood pressure was 88/50 mmHg. An atrial septal defect was seen on an echocardiogram and signs of left ventricular hypertrophy were present electrocardiograpically. Ultrasonography (USG) and computed tomography revealed two vessels originating from the host; there were no other structuresintheconnectionbetweenthetwins. A 6-cm-diameter, intact omphalocele sac was presentbelowtheparasitictwinandcontained intestinal segments and liver. The parasitic twinwasattachedtothehosttwinatthexiphoid region in an opposite and ``horseriding'' manner (Fig. 1). He was acephalic and had a rudimentary thorax, a small abdomen, two incomplete upper limbs (The right hand containedthreedigits,thelefthandwascleft),two well-formed lower limbs (four digits on the right foot), a well-developed scrotum but impalpablegonads,apeniswithanatreticurethra after the ®rst cm, and anus imperforatus. At surgical exploration, two vessels were seen entering the parasitic twin from the host.

Surgical separation was done without any diculty. The abdominal defect was repaired primarily. The postoperative course was uneventful; he tolerated oral feedings on the 9th day. IV pyelography and USG were performed postoperatively and no associated anomaly was observed. He was discharged on the 30th postoperative day; the ventral hernia was closed after 6 months. He is currently doing well. When the parasitic twin was examined, the thorax did not contain a heart and lungs. Structures seen in the abdomen included 6 cm distal ileum, a cecum, and colon 25 cm in length ending in a blind rectal pouch. In the rectum, epithelial remnants, and meconium were found. No kidneys, bladder and ureters, or vertebral bodies could be found. Histologic examination of a multicystic retroperitoneal structure 1 cm in diameter revealed a testis.

Discussion Conjoined twins occur with an incidence of 1/50,000 to 1/100,000 births [3]. They are monozygotic, monochorionic twins of the same sex with identical chromosomal patterns. It is believed that the malformation develops soon after the blastula stage [2, 9]. Conjoined twins are classi®ed according to the most prominent site of connection; these regions may include the thorax (thoracopagus), abdomen (omphalopagus-xiphopagus), pelvis (ischiopagus), sacrum (pyopagus), and skull (craniopagus). Thoracopagus is the most common form, accounting for 40% of all reported cases [2, 9]. A Parasitic twin is one that shows unequal development. One twin is normal, the other

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ticipation of problems that may arise during and after separation [10]. Our parasitic twin was separated successfully from the host twin, who is now doing well and being followed up for the cardiac malformation.

References

Fig. 1 Truncal duplication: parasitic twin attached to host twin in xiphoid region

is incompletely developed but usually has a lower trunk and extremities [7]. Knowledge about the embryologic development of the parasitic twin is incomplete. While this variety was classi®ed as heteropagus by Potter, it was termed parasitic twins by Willis, who showed an analogous relationship to acardiac or hemicardiac mammalian twins [10]. The blood circulation of the parasitic twin is reversed, i.e., deoxygenated blood is supplied from the umblical artery of the host twin, which causes major malformations: the twin may be acephalic, paracephalic, or amorphous. According to Willis, in conjoined parasitic twins an acardiac, acephalic twin occurs with only limbs attached to an epigastrium [6, 10]. In our case, since one of the twins was acephalic and had a small abdomen and rudimentary thorax

and extremities, it is classi®ed as a truncal duplication. The ®rst case of truncal duplication was reported by Sarihan et al. [8]. There was great similarity between that case and ours: they had the same localization and similar associated malformations. Sarihan's case also had a colon perforation and meconium peritonitis. To our knowledge, ours is only the second reported case. At pathologic examination of the parasitic twin, Although no hepatobiliary tree was detected, bile-stained meconium was seen in the intestinal lumen. This can be explained by a vanishing functional hepatobiliary system damaged as a result of a vascular accident. Successful management depends not only on the general condition of the infants and the complexity of their attachment and organ sharing, but also on through planning and an-

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