Diagnostic and prognostic value of CD10 in peripheral nerve sheath tumors.

Neurofibromas are sporadic or associated with type 1 neurofibromatosis (NF1), with a higher risk of malignant progression. We investigated CD10 immunoexpression in 39 peripheral nerve sheath lesions. They were 18 typical, solitary, sporadic neurofibromas (group A) and 21 cases (group B) consisting of 11 NF1-associated cases, 3 malignant peripheral sheath tumors (MPNST) and 8 atypical neurofibromas. CD10 immunopositivity was absent or very weak and focal in group A. On the contrary, CD10 was strongly expressed in group B, including all the MPNST and their metastases, with 95% sensitivity and 72% specificity in distinguishing between the two groups. CD10 is useful in the assessment of peripheral sheath tumors and could give evidence that atypical myxoid and/or diffuse neurofibromas, sometimes histologically difficult to distinguish from low-grade MPNST, represent not only a histological but also an immunohistochemical continuum with MPNST.