malignant Triton tumour
A rare peripheral nerve tumour with skeletal muscle differentiation that is either benign (neuromuscular hamartoma), or malignant–and comprised of malignant schwannoma cells and
malignant rhabdomyoblasts, classically linked to prior irradiation
Epidemiology Triton tumours usually occur in the head, neck and trunk; peak incidence, age 35. They are often associated with von Recklinghausen’s disease.
Clinical findings Often neurologic symptoms related to tumour enlargement.
Prognosis Poor; 5-year survival 12%.
Histopathology Scattered rhabdomyoblasts that may have cross-striations in malignant schwannoma-like stroma (left panel); desmin (right) and myoglobin seen by immunohistochemical (IHC) stains
The name derives from a group of newts–genus, Amblystoma or small salamanders–genus, Triturus, trivially known as tritons, in which there is an intimate relation between limb degeneration and innervation, a phenomenon first described by JT Todd in 1823. While the presence of nerves is not an absolute prerequisite for limb regeneration (J Exp Zoo 1959; 140:101), the name triton was retained by pathologists as a tribute to the theory that motor nerves could induce endoneural cell differentiation into muscle cells. The salamanders (middle image) in turn received their name from Triton, the son of Poseidon and Amphitrite, an inferior sea-deity who had the head and torso of a man and the tail of a dolphin (top image).
Synonyms Malignant peripheral nerve sheath tumour with rhabdomyosarcomatous differentiation, malignant Triton tumour, peripheral nerve tumour with rhabdomyosarcomatous differentiation
Reference MJ O’Sullivan, et al, Mod Pathol 2000;13(11):1253–1263