Epithelioid schwannoma

Abstract A 17-year-old girl with epithelioid malignant peripheral nerve sheath tumor (MPNST) arising in the sural nerve is reported. The tumor grew in a nodular pattern and was composed of nests and solid trabeculi of tumor cells separated by hyaline stroma. Immunohisto-chemical reactions showed diffuse positivity for S-100 protein and co-expression of vimentin and GFAP in the entire tumor cell population. Cytokeratins (AE1/3) were expressed in scattered tumor cells. Immunohisto-chemistry revealed slender actin-positive stromal cells with long processes interposed between the hyaline matrix and the tumor cells. Ultrastructurally these cells were considered to be fibroblasts and myofibroblasts; others had features of primitive mesenchymal cells, a finding interpreted as a state of low differentiation of the stromal cells. The clinical course of the disease was recurrent and progressive with subsequent lymph node metastases and widespread dissemination. It correlated with an increased mitotic rate and PCNA positivity of the tumor cells at the metastatic sites.
Source: Annals of Diagnostic Paediatric Pathology - Category: Pathology Source Type: research