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low grade malignant peripheral nerve sheath tumor

Tuesday 25 January 2011

A small number of malignant peripheral nerve sheath tumors (MPNSTs) are low grade.

Malignant peripheral nerve sheath tumours (MPNSTs) arise from a peripheral nerve or show intrinsic nerve sheath differentiation.

They comprise approximately 5% of all malignant soft tissue tumours.1 Most are derived from neurofibromas, often of the plexiform type or neurofibromatosis type 1 (NF1), or arise de novo in normal peripheral nerves.

The histological features of MPNST are well known and include hypercellularity, remarkable cytological atypia, increased mitotic activity, and necrosis.

Most MPNSTs are high grade and have a highly aggressive clinical course.

However, in one large series, 18% of MPNSTs were reported as low grade. Other authors have described tumours that have exhibited perineural differentiation.

Differential diagnosis

The diagnosis of low grade MPNST is not easy. First, it is usually difficult to distinguish neurofibromas with varying degrees of atypia from MPNST. Second, the pathological features of low grade MPNST often overlap with those of other soft tissue tumours.

It is usually difficult to distinguish neurofibromas with varying degrees of atypia from malignant peripheral nerve sheath tumour.

References

- Low grade malignant peripheral nerve sheath tumour: varied cytological and histological patterns. Yamaguchi U, Hasegawa T, Hirose T, Chuman H, Kawai A, Ito Y, Beppu Y. J Clin Pathol. 2003 Nov;56(11):826-30. PMID: 14600126 (Free)

- Malignant peripheral nerve sheath tumors. A clinicopathologic study of 120 cases. Ducatman BS, Scheithauer BW, Piepgras DG, Reiman HM, Ilstrup DM. Cancer. 1986 May 15;57(10):2006-21. PMID: 3082508