Perinatal tumours involving the germ cells comprise a group of both benign and malignant neoplasms.1 They are found at a variety of sites, most frequently in the sacrococcygeal region. Intrapericardial tumors are rare. When immature elements, or malignant focuses from the yolk sac, are present, the tumours can be associated with elevated levels of alpha-fetoprotein.2–4 We present a case in which, despite elevated levels of alpha-fetoprotein, the tumour proved to be benign.
Case report
A 32-year-old mother presented at 30 weeks gestation. Ultrasonic investigation revealed important hydrops, with ascites, pleural effusion, and a large and inhomogeneous mass measuring 35 by 34 by 42 millimetres within the pericardial cavity (Fig. 1), compressing both the right atrium and ventricle. A previous ultrasonic examination at 22 weeks had not revealed any abnormality. The baby, weighing 2100 grams, was delivered by caesarean section and intubated. Chest radiography revealed a large cardiac shadow and bilateral pleural effusions. The echocardiogram confirmed the presence of the large intrapericardial mass, without revealing any further cardiac abnormalities. He was transferred to the operating room, where a median sternotomy was performed. After removal of the thymus, the pericardium was opened and the mass was completely excised. Strongly vascularized adhesions were present, connecting the mass to the coverings of the aorta and pulmonary trunk. The child had an uneventful postoperative recovery, and was discharged home at the age of 7 weeks.
Figure 1. Obstetric ultrasound at 28 weeks gestation, revealing the large inhomogeneous intrapericardial mass.
Histological examination of the resected specimen revealed a multilobulated mass, measuring 30 by 40 by 30 millimetres, weighing 24 gram, and containing only benign and mature teratomatous tissue. No immature or malignant focuses were seen, neither were there focuses of yolk sac tumour. The level of alpha-fetoprotein level immediately after birth was 458,700 microgram per litre, where normal levels are less than 13.6. The levels subsequently declined, being measured at 71,830, 31,422, 19,252, 6,991, 111,6 and eventually 44,5 micrograms per litre at intervals of respectively 3, 4, 6, 8, 14 weeks and 6 months.
Discussion
Most germ cell tumours of the fetus or neonate are histological benign, and can be classified as either mature or immature teratomas. Tumours of the yolk sac are the leading malignant tumours involving the germ cells, and carry a significantly worse prognosis. Typically, germ cell tumours grow rapidly between 20 and 40 weeks of pregnancy, which was nicely illustrated in our patient, who had a normal ultrasonic examination at the 22nd week, but had developed a large mass by the 30th week.
Management of intrapericardial teratoma is individualized, and depends on the gestational age and general state of health of the fetus. Intra-uterine pericardiocentesis is an option in a premature fetus with significant pericardial effusion. Most cases presenting during the third trimester of pregnancy are managed by elective caesarean section, followed by resection of the tumour. The surgical removal of an intrapericardial teratoma is usually uncomplicated. Long-term prognosis is good when resection is complete.
The significance of a moderately elevated level of alpha-fetoprotein is questionable in the first year of life. Its reference values in normal term and near-term newborns were only recently defined in a detailed study of 260 children, revealing a large non-normal spread, with the upper limit of the 95% confidence interval at 146,500 microgram per litre.5 Two further elements can increase levels post-natally, specifically prematurity and the presence of a tumour involving the germ cells. A significant negative correlation has been documented between levels of alpha-fetoprotein in the serum and gestational age.5 Should infants be born prematurely, therefore, it is necessary to correct for gestational age when interpreting levels of alpha-fetoprotein. An earlier study had reported elevated levels up to 301,000 micrograms per litre in preterm infants with a gestational age around 30 to 32 weeks.2 The presence perinatally of a tumour of the germ cells produces strongly elevated levels, albeit that in most reported cases, the tumours either contained immature elements3 or malignant elements from the yolk sac.4 All of these cases, however, involved sacrococcygeal tumors. To the best of our knowledge, there is but one report of an intrapericardial teratoma associated with elevated levels of alpha-fetoprotein, this being an immature teratoma found in an infant of 32 weeks gestational age, in whom the initial level was 91,853 micrograms per litre.3
The first measured level postnatally in our patient exceeded 450,000 micrograms per litre, which is extremely high. The drop in levels during follow-up was normal, considering a half-life of approximately 7 days. Our experience shows that a severely elevated level of alpha-fetoprotein is possible in a preterm infant presenting with a benign and mature tumour of the germ cells. The value of the initial level of alpha-fetoprotein in judging the presence of possible immature or malignant elements, therefore, is questionable. Thorough histological examination, complete resection, and subsequent follow-up to establish any decrease in the level of alpha-fetoprotein, are mandatory in these patients.
