Pathology: malignant peripheral nerve sheath tumour
Malignant peripheral nerve sheath tumour
Underlying NF1
Multinodular with "marbled" pattern (variable cellularity)
Spindle-epithelioid cells with pale amphophilic cytoplasm
Ovoid-round nuclei with moderate pleomorphism; conspicuous mitotic activity
Scant myxoid stroma
IHC: H3K27me3
Malignant peripheral nerve sheath tumour
Underlying NF1
"Marbled" pattern (variable cellularity)
Spindle-epithelioid cells with pale amphophilic cytoplasm
Ovoid-round nuclei with moderate pleomorphism; conspicuous mitotic activity
Intervening collagenous-myxoid stroma
IHC: S100
Malignant peripheral nerve sheath tumour, with rhabdomyoblastic differentiation (malignant Triton tumour)
Underlying NF1
Peritheliomatous pattern
Spindle-polygonal cells with amphophilic cytoplasm
Ovoid-round nuclei with marked pleomorphism; conspicuous mitotic activity
Small clusters of rhabdoid cells with abundant eosinophilic cytoplasm; eccentric nuclei with occasional multinucleation
Abundant myxoid stroma
IHC: myogenin, H3K27me3
Malignant peripheral nerve sheath tumour, with rhabdomyoblastic differentiation (malignant Triton tumour)
Fascicles of spindle cells with pale amphophilic cytoplasm
Ovoid-round nuclei with moderate pleomorphism; conspicuous mitotic activity
Interspersed nests of rhabdoid cells with abundant eosinophilic cytoplasm; eccentric round nuclei with macronucleoli
IHC: myogenin, H3K27me3
Malignant peripheral nerve sheath tumour, with rhabdomyoblastic differentiation (malignant Triton tumour)
Short fascicles of spindle cells
Pale amphophilic cytoplasm
Ovoid-round nuclei with coarse chromatin and moderate pleomorphism; conspicuous mitotic activity
Epithelioid cells centred around vessels; patchy necrosis
IHC: desmin, myogenin, H3K27me3
Malignant peripheral nerve sheath tumour, with differentiation mesenchymal (cartilaginous) differentiation
Biphasic with spindle cell and chondroid components
Spindle cells: herringbone pattern; pale amphophilic cytoplasm; ovoid nuclei with mild-moderate pleomorphism; conspicuous mitotic activity
Cartilage: hypo-moderately cellular lobules of stellate-polygonal cells; pale eosinophilic cytoplasm; round hyperchromatic nuclei with mild pleomorphism; rare mitotic activity; abundant hyaline cartilage matrix with myxoid degeneration
IHC: H3K27me3, S100, SOX10
RNA-seq: negative
ISBN: 978-1-933477-30-5