2 | CASE
A 27-year-old female patient found a mass at the right back neck, which was with a size similar to a ”fava bean” without tenderness, redness, or swelling, and with no growth or disappearance seven months ago. The patient described that the size of the mass gradually increased to like an ”adult fist”, which was accompanied with mild tenderness one month ago (Fig.1). She was diagnosed as fibroma in the local hospital and underwent major resection. Postoperative pathology revealed high dysplasia of the tumor, and then the pathological section was sent to the ”West China Hospital of Sichuan University” for pathological examination. The immunohistochemistry results showed: S-100 (+), CD34 (+), desmin (+), H3K27Me3 (-), myogenin (+), MyoD1 (+), SMA (-), STAT-6 (-), P53 (+), NF (-), ALK-1 (-), TRK (-), and the Ki-67 positive rate was 40%. Immunophenotypic testing revealed the presence of more rhabdomyosarcoma components, which was combined with extensive loss of H3K27Me3 protein. Therefore, malignant triton tumor (MTT) was diagnosed.
However, three weeks after the diagnosis, tumor recurrence was observed and the tumor was rapidly increased to the size of an ”adult fist” again. She visited our hospital for surgical treatment. The physical examination showed a mass of approximately 6.4cm×6.5cm×8.9cm at the right back neck. Magnetic Resonance Imaging (MRI) showed a mass of soft tissue that occupied the shadow at the right back neck (Fig.2). On September 18, 2020, we performed surgery to completely remove the tumor. Postoperative pathological analysis by our hospital confirmed MTT (Fig.3). The postoperative tumor specimens were sent to “Beijing Genetron Health Medical Laboratory Co., Ltd.” for genetic testing. The results showed FANCD2 and NF1 gene mutations. No tumor recurrence was observed during the postoperative follow-up, and the patient is currently receiving chemotherapy and radiotherapy regularly.