Low grade malignant peripheral nerve sheath tumour: varied cytological and histological patterns.
BACKGROUND
A small number of malignant peripheral nerve sheath tumours (MPNSTs) are low grade, and the nature of these low grade tumours has never been systematically assessed.


OBJECTIVE
To describe the clinicopathological, immunohistochemical, and ultrastructural features of low grade MPNST and to discuss the main differential diagnoses.


METHODS
Four cases of low grade MPNST were studied, including one coexistent with neurofibromatosis type 1. The tumours were analysed with respect to nuclear atypia, cellularity, nuclear enlargement, hyperchromasia, mitotic rate, and necrosis. Immunohistochemistry was performed by standard techniques, and an ultrastructural study was performed on one tumour.


RESULTS
The ages of the patients ranged from 32 to 72 years (mean, 58). Two were male and two were female. Three tumours occurred in the deep tissue, including one in the retroperitoneum, and one was located in the dermal and subcutaneous tissue. The maximum diameters of the tumours ranged from 3.5 to 8.0 cm. Microscopically, all tumours showed moderate hypercellularity, an increased nuclear to cytoplasmic ratio, and hyperchromasia, but exhibited varied growth patterns, including those that were atypical neurofibroma-like, low grade fibromyxoid sarcoma-like, low grade epithelioid, and haemangiopericytoma-like. All tumours showed immunoreactivity for S-100 protein and vimentin.


CONCLUSIONS
These findings suggest that careful clinical and histological evaluation, along with S-100 protein immunostaining, are essential for the accurate diagnosis of low grade MPNST.
Division of Orthopaedic Oncology, National Cancer Centre, Hospital and Research Institute, Tokyo 104-0045, Japan.
U
U
Yamaguchi
T
T
Hasegawa
T
T
Hirose
H
H
Chuman
A
A
Kawai
Y
Y
Ito
Y
Y
Beppu
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D002467:Cell Nucleus / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006393:Hemangiopericytoma / Q000648:ultrastructure; D006801:Humans; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000032:analysis; D010524:Peripheral Nervous System Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000648:ultrastructure; D009418:S100 Proteins / Q000032:analysis
D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D009418:S100 Proteins