Unusual spindle cell tumor of thyroid (SETTLE).

Area of Science:

• Pathology
• Pediatric Oncology
• Head and Neck Surgery

Background:

• Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a rare neoplasm primarily affecting children and adolescents.
• Its presumed origin is ectopic thymus or branchial pouch remnants differentiating along thymic lines.
• The spindle cell-predominant histology presents diagnostic challenges.

Observation:

• A case of SETTLE presented as a neck mass, initially suspected to be in the submandibular gland area.
• Preoperative imaging supported the submandibular gland location.
• Intraoperative findings revealed the mass was continuous with the left thyroid lobe.

Findings:

• SETTLE can present with unusual anatomical connections, mimicking other neck masses.
• Metastasis has been documented at initial presentation, indicating potential for aggressive behavior.
• Histological features can be misleading, complicating diagnosis.

Implications:

• This case underscores the importance of considering rare diagnoses like SETTLE in pediatric neck masses.
• Enhanced awareness of SETTLE's varied presentations is crucial for accurate diagnosis and management.
• Further research is needed to fully understand the clinical course and optimal treatment strategies for SETTLE.