Diagnostic dilemma in a paediatric poorly differentiated chordoma of the clivus: a case report

Poorly differentiated chordoma is a rare, aggressive chordoma subtype occurring predominantly in paediatric population. We report a paediatric clival poorly differentiated chordoma that posed diagnostic challenges due to atypical clinical, radiological and histological findings. A 1-year-old male child presented with neck stiffness and snoring which later progressed into upper airway obstruction. Initial imaging suggested a retropharyngeal abscess with clival erosion and intraoperatively were reported as undifferentiated sarcoma. Despite chemotherapy the disease progressed. Repeated biopsy with adequate viable tissue revealed sheets of neoplastic cells with absence of physaliphorous cells. The tumor cells were positive for brachyury, CK and EMA and showed loss of INI1 expression, clinching the diagnosis of poorly differentiated chordoma. Unfortunately, due to the aggressiveness of the tumor patient succumbed within months after the diagnosis. This case highlights the importance of adequate tissue sampling, targeted immunohistochemistry, and clinicopathological correlation in diagnosing paediatric poorly differentiated chordoma.