Peripheral nerve sheath differentiation in malignant soft tissue tumours: an ultrastructural and immunohistochemical study

Abstract

Thirteen soft tissue sarcomas with ultrastructural evidence of nerve sheath differentiation were investigated by immunohistochemistry. Three arose in a major nerve or nerve trunk and four patients had von Recklinghausen's neurofibromatosis. Ultrastructurally, 10 cases showed variable differentiation towards Schwann cells, two resembled perineurial cells and one tumour had features suggestive of both cell types. Immunostaining for S-100 protein was positive in eight Schwann cell tumours, negative in the other two Schwann cell tumours and negative in those with perineurial-like cells. No cases demonstrated epithelial membrane antigen, so that the existence of perineurial cells in malignant nerve sheath tumours remains immunohistochemically unsubstantiated; it may be that the perineurial-like cells are merely incompletely differentiated Schwann cells, with nerve sheath differentiation manifesting a continuous spectrum. Leu 7 was detected in four Schwann cell tumours, three of which were ultrastructurally well differentiated. Cytokeratin and desmin were demonstrated only in an undifferentiated pleomorphic area of one Schwann cell tumour. Electronmicroscopy can aid diagnosis by revealing nerve sheath differentiation in malignant soft tissue tumours without demonstrable S-100 protein.

Diverse differentiation in malignant peripheral nerve sheath tumours associated with neurofibromatosis‐1: an immunohistochemical and ultrastructural study

“…Immunoreactivity for S100 protein in MPNSTs has been seen in 50–90%, 6 , 7 , 14 , 15 , 28–30 while the MPNSTs associated with NF‐1 showed its positivity in 70–90% 15 , 28 , 30 . Unexpectedly, S100 protein positivity was obtained in 52% of MPNSTs with NF‐1 in our study.…”

“…These methods can also be applicable to analyse cellular differentiation in MPNSTs. The correlation between the immunoreactivity for S100 protein and Schwannian differentiation is established using ultrastructural or ultrastructural immunohistochemical analysis 11–15 . In contrast, EMA was demonstrated in various types of MPNST such as conventional, epithelioid, and glandular types 12 , 28 , 29 .…”

“…However, recent studies with immunohistochemical methods using antibodies for S100 protein, 6 , 7 epithelial membrane antigen (EMA), 8 , 9 and CD34 10 have helped to clarify which types of cellular components in the peripheral nerve sheath proliferate in these neoplasms. Several authors demonstrated a correlation between the immunoreactivity for S100 protein and Schwannian differentiation 11–15 and that between EMA expression and perineurial cell differentiation on ultrastructural or ultrastructural immunohistochemical analysis 12 , 16 . The significance of the CD34 expression in peripheral nerve sheath tumours remains unclear, though it is expressed in the endoneurium and also in neurofibromas 10 , 17 .…”

Leiomyosarcoma of the head and neck: a clinicopathological study

“…Fibrosarcoma lacks more than very focal muscle markers, and does not express S100 protein or epithelial markers. Malignant peripheral nerve sheath tumour has `bullet‐shaped' nuclei which may be serpentine and focally S100 protein‐positive 35 . Monophasic synovial sarcoma can appear similar to the other two, but differs in having ovoid, smaller rather uniform nuclei and scattered expression of epithelial markers and strong bcl‐2 staining.…”

Soft Tissue Sarcomas in the African Hedgehog (Atelerix Albiventris): Microscopic and Immunohistologic Study of Three Cases

“…7,12 The morphologic features may vary among tumors due to their multiple cell origin, so other tests (immunohistochemistry, electron microscopy) have been used to confirm the diagnosis. 7,9,13,15 Ultrastructural studies were only done on case no. 1, and results were inconclusive.…”