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Evaluation of eight melanocytic and neural crest‐associated markers in a well‐characterised series of 124 malignant peripheral nerve sheath tumours ( MPNST ): useful to distinguish MPNST from melanoma?
Author(s) -
Gaspard Margot,
Lamant Laurence,
Tournier Emilie,
Valentin Thibaud,
Rochaix Philippe,
Terrier Philippe,
RanchereVince Dominique,
Coindre JeanMichel,
Filleron Thomas,
Le Guellec Sophie
Publication year - 2018
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.13740
Subject(s) - microphthalmia associated transcription factor , immunostaining , sox10 , neural crest , melanoma , immunohistochemistry , pathology , context (archaeology) , medicine , differential diagnosis , s100 protein , melanocyte , cancer research , tyrosinase , biology , embryo , paleontology , biochemistry , enzyme , microbiology and biotechnology
Aims The diagnosis of malignant peripheral nerve sheath tumour ( MPNST ) may be challenging, especially in the sporadic setting. Owing to the lack of specific histological criteria, immunohistochemical and molecular diagnostic markers, several differential diagnoses must be considered, especially melanoma. Indeed, although S100 protein usually stains melanoma, other melanocytic markers are often negative, especially in spindle cell/desmoplastic types. This pattern of immunoreactivity resembles that of some nerve‐derived tumours such as MPNST . Owing to their different clinical behaviours and therapeutic implications, accurate identification of these two different tumours is crucial. Methods and results S100, SOX 10, KBA 62, MITF , HMB 45, Melan‐A, tyrosinase PNL 2 and BRAF ‐V600E immunostaining was performed in a pathologically and genetically well‐characterised cohort of primary MPNST ( n = 124), including 66 (53%) NF 1‐associated tumours. Sox10 and KBA 62 expression were found, respectively, in 102 (84%) and in 101 (83%) MPNST , whereas S100 was expressed in 64 cases (52%). We observed an increased loss of S100 with increasing histological grade ( P = 0.0052). We found Melan‐A expression in 14% ( n = 17) of all MPNST , occurring in 82% ( n = 14) of cases in an NF 1 context. Six per cent ( n = 8) of MPNST showed tyrosinase positivity, including seven (87%) NF 1‐associated. MITF expression was found in 10 (8%) MPNST . None expressed PNL 2, HMB 45 or BRAF ‐V600E. Conclusion MPNST (in NF 1 and a sporadic setting) can quite often be positive for Melan‐A, tyrosinase and MITF . Pathologists should be cognisant of these exceptions to prevent confusion with melanoma.