Mediastinal teratomas in children. Case reports and review of the literature.

Background: In the pediatric age, mediastinal teratomas are an infrequent observation, accounting for only 7%-11% of extragonadal teratomas. Mainly located in the anterior mediastinum arising from the thymic gland, or exceptionally, from ectopic thyroid tissue, they may rarely be observed in the posterior mediastinum, sometimes in a paravertebral position, simulating a neuroblastoma. The Authors have extrapolated, from their entire experience of teratomas, 3 cases, mostly operated as emergencies; 1 of them was treated just after birth. Aim of this paper is to report the clinical and pathologic findings, to evaluate the surgical approach and the long-term biological behaviour in these cases, in the light of survival and current insights reported in the literature.

Materials And Methods: The Authors reviewed the most significant clinical, laboratory, radiologic and pathologic findings, surgical procedures, and early and long-term results in 3 children, 2 males and 1 female, suffering from extragonadal teratomas, located in the mediastinum, treated immediately after birth. In 1 of them the lesion was prenatally diagnosed by US scanning between the 2nd and 3rd trimester of pregnancy. All the infants were born by scheduled caesarean section in a tertiary care hospital and were then immediately referred to the N.I.C.U. because of a mostly acute clinical presentation. The 3 patients were referred to the surgical unit at different ages, namely 2 days, 10 years and 12.5 years, respectively. The initial clinical presentation was consistent with the site of the mass and/or its side-effects. The first patient, a female newborn, presented a worsening condition of respiratory distress, immediately after birth, that required mechanical ventilation and stabilization of the vital signs. Likewise, the presentation of case No. 2 was acute with dyspnea associated with an upper airways infection. Instead, the initial symptoms in case No. 3 were subacute and non-specific, characterized by worsening pain at the right shoulder extending to the neck and homolateral arm. The patients underwent laboratory and radiologic investigations that confirmed the clinical diagnosis of teratoma on the basis of elevated AFP values in 2 cases only (Case No. 1 and No. 2), while calcifications were lacking at imaging in all 3 patients. Emergency surgical management was required and, in accordance with recommended practice, the procedure was complete exeresis.

Results: All the patients underwent close long-term clinical, laboratory and imaging surveillance at shorter intervals during the first 5 years after the exeresis and annually thereafter. At the present time they are alive, disease-free and have not suffered any recurrence and/or distant metastases, with a follow-up of 7, 30 and 3 years respectively.

Conclusions: Some extragonadal teratomas of childhood may rarely arise in the mediastinum. Being congenital tumors, prenatal diagnosis by US scan is extremely important in order to organize proper perinatal care in appropriate facilities where it is possible to define the diagnosis, and equipped with appropriate tools to carry out emergency surgery at minimal risk and to prevent severe complications after birth. An emergency procedure is frequently dictated both by complications related to the mass effect, and by the need to define the histology of the whole mass rather than just small biopsy specimens. Some teratomas can hide more or less extensive islands of immaturity or signs of malignant transformation that are clinically evident. It should be noted that calcifications and high levels of AFP and/or beta-HCG, usually pathognomonic elements for diagnosis, may not always be evident during the diagnostic work-up in mediastinal lesions. The prognosis is generally benign, although the AIEOP 2004 guidelines pointed out that high levels of circulating markers, including AFP, in children affected by mature or immature teratomas would indicate the presence of micro-foci of YST, marking them out as at high risk. The UKCCSG II and the SFOP indicated AFP values exceeding 10,000 ng / ml as the threshold identifying a group of patients with a severe prognosis.The treatment indicated is early, complete exeresis, followed by a careful, extensive microscopic examination and associated, if necessary, with adjuvant chemotherapy. Finally, in accordance with recommended practice, close, long-term clinical, laboratory and imaging surveillance is necessary, at shorter intervals during the first 5 years after the exeresis.