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Journal of Postgraduate Medicine, Vol. 57, No. 3, July-September, 2011, pp. 229-230 Images in Pathology Ectopic liver tissue in umbilical cord P Vaideeswar1, D Yewatkar2, R Nanavati2, P Bhuiyan3 1 Department of Pathology, Seth GS Medical College and KEM Hospital, Mumbai, Maharashtra, India Date of Submission: 12-Feb-2011 Code Number: jp11064 PMID: 21941067 A 12-hour-old female child was admitted at our center for extreme respiratory distress. The baby was cyanosed with heart rate of 40 per minute and feeble pulses. She was born at 39 weeks by full-term normal vaginal (home) delivery with birth weight of 2,460 g. There were no apparent perinatal complications. The mother had undergone ultrasonography at 32 weeks of gestation, which revealed hypoplasia of the left-side of the heart. In addition, a hyperechoic area 2 - 2 cm was seen at base of the umbilical cord. There had been no proper antenatal care. Despite resuscitative measures, the child expired within 25 minutes of admission. A complete autopsy was performed. The umbilical cord, 2.8 cm away from its insertion, revealed a pebble-sized firm, circumscribed, light brown nodule, which on histology was wholly composed of ectopic liver tissue, replete with portal tracts [Figure - 1]. The hepatocytes had pale, vacuolated cytoplasm. This liver tissue had no connection to the main liver mass. The other cross-sections of the cord revealed an artery and a vein (both with thick walls), an obliterated vessel, small hepatocytic nodules, allantoic cysts, and funiculitis [Figure - 2]. Other findings at autopsy were double outlet right ventricle (side-by-side great arterial relationship, subaortic ventricular septal defect, absent pulmonary stenosis), agenesis of right lung, and hyaline membrane disease in the left lung. Discussion Ectopic liver is an unusual developmental anomaly and is defined according to Collan et al.[1] as an anomalous location of liver tissue without connection to the main liver mass. The liver develops from an endodermal bud from the most caudal part of the foregut around the fourth week of gestation. This hepatic bud divides into a larger cranial portion, the pars hepatica (forming the hepatic parenchyma), and a smaller caudal portion, the pars cystica (forming the extrabiliary system). The close relationship of these two parts explains the reason why the gall bladder is the commonest site for ectopic liver. [2] Several theories have been proposed to explain occurrence of ectopic liver at sites other than the gall bladder, such as development of an accessory hepatic lobe that has lost its connection to the main liver, displacement or migration of part of the pars hepatica to other sites, dorsal budding of hepatic tissue before closing of the pleuroperitoneal canals, trapping of hepatocyte-destined mesenchyme in different areas, or entrapment of nests of cells in the region of the foregut following closure of the diaphragm. [2] Hence, ectopic liver can be seen both below and above the diaphragm. On the other hand, ectopic liver in the umbilical cord is exceptional and only four cases have been reported so far. [3],[4],[5],[6] We have reported the fifth case. In only one case, the ectopic liver was identified prenatally as a solid mass lesion, [6] as seen in our case. Hence, liver choristoma must be considered in the differential diagnoses of rare umbilical cord solid masses such as hematomas, benign vascular neoplasms, and teratomas. [5] The underlying basis for ectopic liver in cord is not exactly known. It is possible that a part of normal liver becomes entrapped outside the abdomen by the umbilical ring closure or there may be aberrant differentiation of the endoderm, which is common to the allantois, urachal progenitor, and liver. [6] This probably explains presence of small islands composed only of hepatocytes around the allantoic cyst in this case. The histological architecture of the main mass however resembled normal liver with regular acini, central veins, and portal tracts. There were two other interesting features. This is the first report where cord ectopic liver was associated with conotruncal cardiac and pulmonary anomalies. The latter usually occurs with thoracic ectopic liver, an association explained by close proximity of the developing hepatic diverticulum, septum transversum, and aorticopulmonary septum. [7] Another feature was the presence of an obliterated artery and hence it may be possible that this seemingly innocuous finding may result in intrauterine death in cases devoid of cardiac anomalies. References
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