Malignant triton-tumor C47.9

The rare MPNST variant with a rhabdomyosarcomatous component was first described as a tumor entity by Masson in 1932 (Masson P (1932) and first termed "malignant Triton tumor" (MTT) by Woodruff et al in 1973 (Woodruff JW et al (1973).

Divergent histologic differentiation is a well-known phenomenon in malignant peripheral nerve sheath tumors (MPNST). Malignant Triton tumor may be associated with neurofibomatosis type 1 (NF-1) and is characterized by mesenchymal elements with either rhabdomyoblastic, chondroid, myoid, or osteoid differentiation. Differentiation with additional epithelial components is a very rare occurrence, with the first glandular malignant schwannoma (MPNST with glandular differentiation) described by Garré in 1892 (Garré C (1892).

Due to the rare occurrence, there is no binding therapy recommendation, especially for the adjuvant situation. The decisive prognostic factor is radical resection.

The overall prognosis of Triton malignant tumor is poor, with a 5-JÜR of 35%. The tumor is prone to both local recurrence and distant metastasis.

The name Triton tumor originated from studies of Triton salamanders in which supernumerary extremities grew with bone and muscle after implantation of sciatic nerves in the back.

1. Chaudhry IU et al. (2016) Radical resection and improvised surgical reconstruction for a rare malignant triton tumour of intercostal nerve in a patient with neurofibromatosis type 1. BMJ Case Reports doi: 10.1136/bcr-2016-217868.
2. Chaudhry I et al (2019) Mediastinal malignant triton tumor: A rare case series and review of literature. International Journal of Surgery Case Reports 62:115-119.
3. Garré C (1892) On secondary malignant neuromas. Contributions to clinical surgery 9:465-495.
4. Masson P (1932) Recklinghausen's neurofibromatosis, sensory neuromas and motor neuromas. In: Contributions to the medical sciences in honor of Dr. Emanuel Libman Anniversary New York, NY: The International Press 793-802.
5. Woodruff JW et al (1973) Peripheral nerve tumors with rhabdomyosarcomatous differentiation (malignant "triton" tumors) Cancer 32:426-439.