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malignant Triton tumor

Friday 6 January 2006

Definition: A malignant peripheral nerve sheath tumor (MPNST) with rhabdomyoblastic differenciation.


- Malignant Triton tumor (MPNST w rhabdomyoblasts) in NF-1 patient. Desmin+.

Localization (Examples)

- rectum (15827834)


- sporadic or in the setting of neurofibromatosis 1 (NF1)
- scattered rhabdomyoblasts in a stroma identical to ordinary MPNST :

  • usually rather mature, with abundant eosinophilic cytoplasm
  • cross-striations
  • immunohistochemistry : desmin, MyoD1 and myogenin positive

See also

- malignant peripheral nerve sheath tumor (MPNST)


- Daimaru Y, Hashimoto H, Enjoji M. Malignant "triton" tumors: a clinicopathologic and immunohistochemical study of nine cases. Hum Pathol. 1984 Aug;15(8):768-78. PMID: 6235165