A Rapidly Growing Cervical Tumor in an Infant: Sarcoma with <i>BCOR</i> Gene Alterations

Cervical masses in infants are most often benign, typically of congenital or infectious origin; however, malignancies do occur and vary by anatomical location. Among malignant tumors, rhabdomyosarcoma is the most common soft tissue sarcoma of the head and neck in this age group. We present a neonate with a rapidly enlarging cervical mass, ultimately diagnosed as a high-grade sarcoma with a BCL6 corepressor (BCOR) alteration. At two months of age, the infant developed a rapidly growing tumor in the left submandibular region, resulting in respiratory distress. Imaging revealed a firm, homogeneous 3 cm mass adherent to deep cervical tissues. Surgical resection achieved approximately 80% tumor removal; intraoperatively, the mass appeared highly vascularized. Definitive diagnosis required advanced molecular testing, which identified a <i>BCOR</i> gene alteration and informed targeted therapeutic planning. At six-month follow-up, the patient remained clinically stable, with no evidence of local recurrence or distant metastasis. This patient's presentation underscores the essential role of comprehensive genomic profiling in distinguishing between histologically similar pediatric sarcomas and guiding appropriate, individualized treatment.