Malignant schwannoma presenting as a skin mass. Confirmation by the demonstration of myelin basic protein within tumor cells

A malignant spindle cell tumor with features of a malignant schwannoma presented as a skin mass in the neck of a 13-year-old child. The histologic diagnosis was supported by the demonstration of myelin basic protein within the atypical cells using a monoclonal antibody to myelin basic protein and an unlabelled antibody peroxidase-antiperoxidase technique.