Immunoprofiles in malignant peripheral nerve sheath tumor: three case reports and literature review.

Because there are no standardized radiologic and histologic criteria, the differential diagnosis of malignant peripheral nerve sheath tumors (MPNSTs) from other spindle cell neoplasms poses great challenges for pathologists. Because early diagnosis of MPNSTs arising from benign peripheral nerve sheath tumors (BPNSTs) means a better prognosis, many immunohistochemical and molecular studies have recently emerged. Nevertheless, no gold standard diagnostic criterion is to be found in the literature. For example, S-100 protein is widely used in the diagnosis of MPNST. Other promising ancillary markers are p53 and Ki-67; however, the staining patterns and possible mechanisms of these markers are seldom mentioned in the literature. These evoke our interest. Only six cases diagnosed as MPNST were retrieved from the archives of the Department of Pathology, Kaohsiung Medical University Chung-Ho Memorial Hospital between 1988 and September 2005. Clinical files were available for three of them, and we found nuances in the immunohistochemistry from these previous reports. Here, we present these rare sarcomas and review the literature.