Background: Malignant tumors in neonates are rare.
Case characteristics: A tumor was detected in the left biceps of a 3-day old neonate. Tumor biopsy and molecular study confirmed the diagnosis of synovial sarcoma. The child received multi-modality treatment with surgery and chemotherapy.
Outcome: The child is disease-free on follow-up period of 12 months.
Message: Synovial sarcoma can rarely occur in a neonate.