«Many thanks for asking me to look at this man's perivertebral mass in the neck, wich is invading bone. I am returning your original stained slides and the blocks herein.
This is indeed an unusual tumuor wich is difficult to classify, at least on H&E. This is a notably infiltrative lesion which has variably epitheloid or focally more spindle-cell morphology. The lesional cells have mildly atypical vesicular ovoid or more tapering nuclei and palely eosinophilic cytoplasm. Our immunostains mirror your own in showing multifocal strong positivity for S-100 protein and there is also multifocal positivity for GFAP, in context consistent with schwannian differentiation, while SMA, EMA, CD34, HMB43, MART-1 and MITF are negative. Although the appearances are rather unusual (and do not fit with any benign lesion), taking into account the infiltrative growth pattern and mild cytologic atypin, I believe that this lesion is best regarded as a malignant peripheral nerve sheath tumour, low-grade, with epithelioid features. Since the tumour involves excision margins, there is certainly a distinct likelihood of local recurrence.
Christopher D.M. Fletcher
Professor of Pathology
Harvard Medical School
Chief of Onco-Pathology
Dana-Farber Cancer Institute»
