Evidence of a dual histogenetic pathway of sacrococcygeal teratomas

Aims Sacrococcygeal teratomas are rare tumors that occur most frequently in neonates, although adult cases also occur. Molecular pathogenesis of these tumors and their long-term prognosis is uncertain. Methods and results Fifty-four sacrococcygeal teratoma specimens from 52 patients were identified and available follow up information was obtained. Fluorescent in situ hybridization analysis was performed to identify isochromosome 12p (i(12p)) abnormalities on paraffin blocks of the tumors. Among the 48 pediatric patients, there were 44 teratomas and 4 tumors with combined teratoma and yolk sac tumor (1 of which also had primitive neuroectodermal tumor). The teratomas included 37 mature teratomas and 11 immature teratomas (4 grade 1, 2 grade 2, and 5 grade 3). The 44 teratomas lacking a yolk sac tumor component were all negative for i(12p). The 4 tumors with a yolk sac tumor component were all positive for i(12p). The 4 adult cases all lacked nonteratomatous germ cell tumor components, immature elements, and i(12p). Follow up information was available for 32 patients. Two patients with teratoma had recurrence, but were alive with no evidence of disease after long-term follow up. One patient with combined teratoma and yolk sac tumor had recurrence 7 months after resection. The other patients were alive with no evidence of disease at last follow up. Conclusions Our data suggest that pediatric sacrococcygeal teratomas should be considered as two distinct groups with a divergent histogenetic pathway. Prognosis of these tumors is excellent, despite rare recurrence. This article is protected by copyright. All rights reserved.