A Rare Case of Epithelioid Malignant Peripheral Nerve Sheath Tumor Mimicking Malignant Melanoma

Abstract

Biglow et al. This is an open access article distributed under the terms of the Creative Commons Attribution License CC-BY 4.0., which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

PRAME expression in spindle cell melanoma, malignant peripheral nerve sheath tumour, and other cutaneous sarcomatoid neoplasms: a comparative analysis

“…Many of these melanomas are poorly differentiated, expressing only S100 or SOX10, while expression of other melanocytic markers is diminished or absent 18,34 . Such characteristics render the distinction between spindle cell melanoma and MPNST particularly difficult, especially when S100 or SOX10 expression is patchy or focal, or in the setting of metastatic disease 14,16,17 . PRAME IHC has recently become a widely adopted ancillary tool in the evaluation of challenging melanocytic tumours.…”

“…14 In particular, differentiation between MPNST and spindle cell/sarcomatoid melanoma is notoriously difficult, as these tumours may share strikingly similar histomorphology and immunophenotype. 16,17 S100 and SOX10 are often the only melanocytic/schwannian markers expressed in these tumours, 17,18 and about half of MPNSTs even lack expression for at least one of these markers. 17,[19][20][21] A relatively new immunohistochemical tool is H3K27me3, an epigenetic marker frequently lost in MPNST and retained in its histologic mimics, including melanoma.…”

“…Diagnosis of MPNST is challenging due to the lack of pathognomonic histopathologic features, specific immunophenotype, or diagnostic molecular signatures 14 . In particular, differentiation between MPNST and spindle cell/sarcomatoid melanoma is notoriously difficult, as these tumours may share strikingly similar histomorphology and immunophenotype 16,17 . S100 and SOX10 are often the only melanocytic/schwannian markers expressed in these tumours, 17,18 and about half of MPNSTs even lack expression for at least one of these markers 17,19–21 .…”

Malignant Peripheral Nerve Sheath Tumor of the Cerebellar Hemisphere: An Unusual Location and Multiple Intracranial Parenchyma Metastases

“…MPNSTs are malignant neoplasms accounting for only 3-5% of soft tissue sarcomas [1]. Neurofibromatosis type-1 (NF1) patients have a cumulative lifetime risk of developing MPNST of 8-16%, and the predilection age is 20-35 years [2].…”

“…Malignant peripheral nerve sheath tumors (MPNSTs) are rare soft tissue sarcomas, often associated with neurofibromatosis type-1 [1][2]. In addition, the incidence of MPNST is high in patients with a history of radiation therapy [3].…”