Imaging Progress and Treatment of Malignant Triton Tumor of the Skull Base

Reporting the clinical course and management of a skull base malignant triton tumor in a child.

An 11-year-old female patient initially presented at the age of 7 with left parotid gland swelling, exhibiting symptoms similar to parotitis. Magnetic resonance imaging (MRI) of the head performed at an external hospital suggested a neoplastic lesion in the left parotid gland and the left parasellar region. Six months later, a parotid gland biopsy was conducted. Postoperative pathology confirmed the diagnosis of embryonal rhabdomyosarcoma. Following the biopsy, the patient underwent one year of radiotherapy and chemotherapy. A follow-up head MRI examination revealed that the lesions in the parotid gland and the left parasellar region had completely resolved. The patient did not adhere to a regular schedule of follow-up examinations. At the age of 10, a follow-up head MRI revealed recurrence of the lesions in the left parotid gland and the left parasellar region. The patient subsequently underwent resection of the left parotid gland lesion at an external hospital. Postoperative pathologic analysis once again indicated embryonal rhabdomyosarcoma. The patient underwent genetic testing, which revealed a germline pathogenic mutation: NF1 p.L952Ffs*2, suggesting an inherited form of NF1. Chemotherapy was subsequently continued. A follow-up MRI performed 5 months after the second surgery showed no recurrence of the left parotid gland lesion; however, the left parasellar region lesion remained unchanged in size. A follow-up head MRI at 9 months postsecond surgery indicated an increase in the size of the left parasellar region tumor. By 10 months postsecond surgery, a follow-up head MRI showed a reduction in the left parasellar region lesion, with no recurrence of the left parotid gland lesion, leading to the discontinuation of chemotherapy. At 14 months postsecond surgery, a follow-up MRI revealed an enlargement of the left parasellar region lesion. The patient received 2 courses of chemotherapy, but a subsequent MRI showed continued growth of the left parasellar region lesion, accompanied by abnormal enhancement of the parotid gland lesion. The patient was then transferred to our department, where they underwent a left temporo-occipital craniotomy for tumor resection. Postoperative pathologic examination confirmed the diagnosis of a malignant triton tumor. Molecular pathologic testing was also performed. The patient recovered well and was discharged successfully.

The patient died from cachexia caused by widespread dissemination of the parotid tumor 4 months after discharge.

Pediatric skull base malignant triton tumors lack specific imaging manifestations. Radiotherapy and pharmacotherapy are insufficient to control tumor growth. Surgical resection remains the primary treatment method, yet the overall prognosis is poor.