Malignant triton tumour of the thigh - A retrospective analysis of nine cases

The Royal Orthopaedic Hospital Oncology Service, Royal Orthopaedic Hospital, Bristol Road South, Northfield, Birmingham B31 2AP, UK.
European Journal of Surgical Oncology (Impact Factor: 2.89). 09/2006; 32(7):808-10. DOI: 10.1016/j.ejso.2006.04.008
Source: PubMed

ABSTRACT Malignant triton tumour (MTT) is a very rare soft tissue tumour.
To report nine patients diagnosed with malignant triton tumour of the thigh between January 1996 and January 2005 to determine the natural history and factors that may affect survival in this aggressive tumour.
Due to the association of Neurofibromatosis (NF Type I) with malignant triton tumour, two groups of patients were identified: those with NF type I (Group I cases); and those without (Group II).
Group I patients accounted for four cases and arose predominantly in young males, all tumours being high grade, >10 cm in size and all four patients died within two years of diagnosis. By contrast, the five patients of Group II were older, had smaller size and lower grade tumours and three patients are long-term survivors.
Although the number of cases is small, our data supports the views that the natural history of MTT is more aggressive in patients with NF type I. This poor outlook could be attributed to the high frequency of Grade III histology in this disease and the large tumour size.

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    ABSTRACT: Rhabdomyoblastic differentiation in a malignant peripheral nerve sheath tumor (MPNST) is termed malignant triton tumor (MTT), a rare neoplasm that poses a diagnostic dilemma in the differential diagnosis of neck masses and portends poor prognosis. We report a sporadic case of MTT of the neck in a 23-year-old female. We present the pathological findings. Immunohistochemistry confirmed the neurogenic origin with S-100 expression and the rhabdomyoblastic differentiation with desmin and vimentin positivity. Radical surgical excision was done. After 4 years there were no signs of recurrence or distant metastasis. The clinical, microscopic, and long-term follow-up of this case are consistent with those of a low-grade malignancy.
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