MPNST sheath tumor

KER, keratin, detected by a mixture of GAMS.2, MAK-6, and AEl /AE3 EMA, epithelial membrane antigen VIM, vimentin DES, desmin MSA, muscle-specific actin SMA, smooth muscle (alpha isoform) actin GALD, h-caldesmon S-IOOP, S-100 protein OCN, osteocalcin LM, laminin UL, Ulex europaeus I lectin binding FS, fibrosarcoma SGRMS, spindle cell rhabdomyosarcoma LMS, leiomyosarcoma MPNST, malignant peripheral nerve sheath tumor MSS, monophasic spindle cell synovial sarcoma SCAS, spindle cell angiosarcoma KS, Kaposi s sarcoma FOS, fibroblastic osteosarcoma. 

FIGURE 4.17 CD57 in malignant peripheral nerve sheath tumor (MPNST). Reactivity for S-100 protein, CD57, myelin basic protein, or collagen type IV is observed in greater than 85% of MPNSTs. 

Determinants associated with non-neoplastic Schwann cells and benign peripheral nerve sheath tumors are frequently detected in MPNSTs. They show reactivity for... 

Malignant peripheral nerve sheath tumor (MPNST) may likewise assume a pleomorphic appearance. In most instances, that tumor variant shows patterns of reactivity for S-100 protein, CD56, CD57, and collagen type IV that are superimposable with those of better differentiated (spindle cell) MPNSTs." In the absence of focal S-100 protein expression and foci with conventional appearances, it is very difficult (if not impossible) to render this diagnosis with certainty. Unlike spindle cell variants of MPNST, pleomorphic subtypes have not been shown to be desmin-reactive. 

Round cell liposarcoma is a morphologic variant of high grade MLPS that may resemble extraskeletal chondrosarcoma, cellular peripheral nerve sheath tumors, or even metastatic poorly differentiated carcinomas. S-100 protein and vimentin are seen in all these tumor types. MPNSTs that are similar microscopically to round cell liposarcoma may express CD56 or myelin basic protein, unlike adipocytic lesions. 

Hirose T, Scheithauer BW, Sano T. Perineurial malignant peripheral nerve sheath tumor (MPNST) A clinicopathologic, immunohistochemical, and ultrastructural study of seven cases. Am J Surg Pathol. 1998 22 1368-1378. 

GFAP, glial fibrillary acidic protein MPNST, malignant peripheral nerve sheath tumor. 

In addition, mice canying linked geimline mutations in Nfl and p53 develop mahgnant peripheral nerve sheath tumors (MPNSTs), which supports a cooperative and causal role for p53 mutations in MPNST development. 

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