Abstract
Melena is reported in 1 of 350 to 400 new-borns. Significant upper gastrointestinal bleeding in a neonate with an antenatally diagnosed abdominal mass has not been reported before. This case highlights an unusual presentation of a gastric teratoma and proposes a probable embryological explanation for the site of occurrence.
Introduction
Gastrointestinal (GI) bleeding in neonates is mostly self-limiting and benign. Incidence of upper GI bleeding is about 1.2% in healthy neonates and 20% in those admitted to intensive care units [1]. Swallowed maternal blood, gastritis, esophagitis, sepsis and haemorrhagic disease of the new born are common causes. Although distressing for the parents, most can be managed conservatively. However, surgical intervention is occasionally needed as illustrated by the following report
Case report
A 3.5 kg baby boy was born through a normal vaginal delivery at term, to non-consanguineous parents. Although the child had melena since birth, it was small in quantity and intermittent. He was breast feeding and well, and hence discharged from the first hospital with reassurance to the parents on postnatal day 3.
On postnatal day 20, the mother noticed upper abdominal fullness for which she consulted a doctor at another hospital and it was found that the baby’s haemoglobin was 4 gm/dl. The baby presented to our centre on postnatal day 27 with anaemia, despite three blood transfusions the previous week. He was feeding well with occasional non bilious, non-projectile vomiting and had no history of hematemesis.
On examination, the baby had good cry, tone and activity with a heart rate of 140/min and a blood pressure of 85/56 mm Hg. He had mild respiratory distress with upper abdominal fullness. On abdominal examination a firm, lobulated, 5×7 cm mass was palpable in the left hypochondrium which was non-tender and not crossing the midline. There were no features of liver disease, skin manifestations of coagulation disorders, bleeding diathesis or anal fissure.
On enquiry, early antenatal scans were normal. 36-week scan showed an irregular, cystic, heterogenous lesion 3.6×2.7×2.7 cm in size, in the left upper quadrant. Postnatal ultrasonogram revealed rapid increase in size of the lesion to 6×5×7 cm at postnatal day 20, with mixed echogenicity, cystic spaces and calcifications. The liver and other solid organs were normal. Contrast enhanced computed tomography of the abdomen on postnatal day 28, revealed a 7.8×5.8 cm lesion with multiple calcifications and tooth like structures within (Fig. 1). The lesion was seen extending intra-luminally into the stomach. Left adrenal was not visualized separately.
Sagittal section of the contrast enhanced computed tomography imaging of the abdomen showing the dumbbell nature of the tumour.
Haemoglobin at admission was 7.7 gm/dl. Other haematological parameters including liver function tests and coagulation profile were normal. Tumour markers were as follows - AFP- 289.2 ng/mL (normal range for age 30- 4,754 ng/ml), HCG-<0.6 mIU/ mL (normal range for age < 10 mIU/ml), urine VMA - 2.29 mg/L, VMA/ creatinine- 14.49 mg/gm.
At laparotomy, an 8×6 cm dumbbell shaped tumor with an intragastric component of 3×2 cm in size was found. The extra gastric component was nestled within the lesser sac between the pancreas, spleen, diaphragm and the left lobe of liver (Fig. 2).Tumor was infiltrating into the wall of the stomach for a distance of 2.5 cm towards the fundus just distal to the gastroesophageal junction. The lesion was excised in toto along with a 1 cm rim of the normal stomach (Fig. 3). There was no retroperitoneal extension. The histopathological examination revealed a mature teratoma with all three germ layers and focal areas of ulceration
Intraoperative picture showing exogastric (EX) and endogastric (EN) components with stomach opened (yellow star).
Intra operative specimen image showing the exogastric and endogastric components of the lesion and its orientation along the greater curvature.
Child had an uneventful recovery with no further episodes of melena. He was discharged home on full feeds and is well at 6 months follow up.
Antenatally diagnosed abdominal lesions are mostly benign. These include mesenteric cyst, ovarian cyst, choledochal cyst, hydronephrosis, pancreatic, splenic, or renal cyst. Antenatally diagnosed tumors include neuroblastoma, hepatoblastoma, Wilms’ tumour, cardiac tumours, sacrococcygeal teratoma and anecdotal reports of teratomas at other sites [2].
Gastric teratoma is seen in less than 1% of the paediatric population with only 120 cases reported in literature previously. In children, the most common age group of presentation is infancy, followed by neonates and then toddlers [3]. Unlike teratoma in general, which has a 68% female preponderance, neonatal gastric teratomas are found mostly in males [4].
First described in 1922, gastric teratoma is commonly found in the greater curvature. It can be exogastric (65%), exogastric with an endogastric component (26%) or purely endogastric (9%) [5]. Abdominal distension with vomiting is the commonest presentation. Some children may present with abdominal mass and respiratory distress [6]. Other unusual presentations are peritonitis due to rupture and gastric perforation [7]. The endogastric component can cause gastrointestinal bleeding in the form of hematemesis or melena but is uncommon in newborns with only 5 cases reported till date [8].
Teratomas contain tissue from all 3 germ layers and hence trace their origin to pluripotent stem cells. These pluripotent stem cells arise from either the primordial germ cells (PGC) during their migration towards the gonadal ridge or directly from the epiblast cells that give rise to the three germ layers during gastrulation. Recent evidences from cytogenetics and genomic imprinting of teratomas strongly favour PGCs as the cell of origin [9]. The formation and migration of these cells towards the wall of the yolk sac occurs between 2nd -4th week of gestation, during which time a few PGCs may get lost and implant themselves in any part of the embryo. Survival of these aberrant PGCs depends on the presence of stem cell niches which provide essential feeder cells and are characteristically in the midline of the developing embryo [9]. We hypothesize that the cell of origin for a gastric teratoma is the PGC which has survived after its aberrant migration into the mesoderm cells of the posterior wall of the foregut because of the presence of a midline niche. By 6 weeks of gestation, the foregut rotates to bring the posterior wall to the left side. Differential growth of this segment ultimately forms the greater curvature of the stomach which thus becomes the most common site of occurrence of gastric teratoma.
Ninety percent of gastric teratomas are benign [10]. Alpha feto protein (AFP) as a tumor marker is used to identify an immature variant, residual lesion or recurrence. Treatment of mature teratomas is primary surgical excision without the need for adjuvant chemotherapy or radiotherapy. Regular follow up is recommended post excision, lest a rare recurrence is missed.
Conclusion
Antenatal detection and melena as the presentation of neonatal gastric teratoma is rare. Complete surgical excision ensures cure in mature teratoma. Probable embryologic explanation for the preferential occurrence of a gastric teratoma in the greater curvature is discussed.