A rare neoplastic disorder characterized by benign metastatic masses increasing in size and number after chemotherapy for non-seminomatous germ cell tumors of testis or ovary. It may present at any time after chemotherapy with a median occurrence within 24 months after treatment completion. Per definition the resected specimen exclusively contains mature teratoma components and serum tumor markers have normalized. The retroperitoneum is the most common site although almost any other localization has been reported. Increased tumor size may cause mechanical compression of vital organs with renal dysfunction bowel ischemia and biliary obstruction as major complications.
Data from Orphanet are used to provide information on a disease's name, synonym(s), and overview. Reference: Access aggregated data from Orphanet at Orphadata. Orphadata: Free access data from Orphanet. © INSERM 1999. Available on http://www.orphadata.org. Data version April 2026
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Growing teratoma syndrome?
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Advocacy Organizations
Pediatric Brain Tumor Foundation
Since 1991, the Pediatric Brain Tumor Foundation has led in funding research, supporting families, and advocating for policies to help patients and survivors. As the largest patient advocacy funder, it drives vital discoveries, new trials, and better treatments. Guided by patient and family experiences, PBTF supports families’ needs at every stage, focusing on care of the entire family.
The JDS Foundation
A foundation that specializes in financial support to high risk and terminal cancer patients to assist in treatment, travel expenses, end of life wishes, outreach, and public awareness.
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Clinical Trials
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