Definition

Malignant Triton tumor is a variant of malignant peripheral nerve sheath tumor (→ see dedicated section) characterized by a rhabdomyoblastic cell component and a more aggressive behavior (worse prognosis) as compared to conventional MPNST.

This heterologous differentiation occurs in up to in 10% of cases and leads some investigators to consider Triton tumor as a mesenchymoma (→ see dedicated section).

The name “Triton” refers to experiments performed on salamanders of the genus Triturus (also known as Tritons), in which implantation of the cut end of a sciatic nerve into the soft tissue of the back resulted in the growth of a supernumerary limb.

The name includes the term “malignant” to differentiate this malignancy from the so-called benign Triton tumor (→ see dedicated section), a synonymous of neuromuscular choristoma (a rare benign peripheral nerve lesion in which well-differentiated skeletal muscle fibers are intimately associated or admixed with mature nerve fibers).