KRT7 and neurofibrosarcoma: In this study, based on their morphologic features diagnostic for human neurofibrosarcoma, i.e., growth pattern and microscopic features (such as areas of high cellularity, cellular pleomorphism, various morphologic patterns, high mitotic index and high number of undifferentiated neoplastic cells), together with the presence of intratumoral papillary cysts and the restriction of the CK7 immunostaining to a subpopulation of the neoplastic cells, the tumour was diagnosed as neurofibrosarcoma.