Clinical and biological features of an intranodal palisaded myofibroblastoma.

Intranodal palisaded myofibroblastoma (IPM) is a rare benign tumor of the lymph nodes probably arising from smooth muscle-like cells. The tumor is characterized by intranodal proliferation of spindle cells. Neoplastic spindle-cell proliferation is most often of metastatic repetition which is very important in the recognition of IPM, because it may be mistaken for metastasis or other tumors such as Kaposi's sarcoma. We report a novel case of IPM that confirms the myofibroblastic differentiation of the tumor. The onset of IPM has been associated with Epstein-Barr virus (EBV). In addition, recently reported cases of IPM have been seen with cyclin 1 overexpression and also with human herpes virus (HHV)-8 and EBV DNA sequences. In our case, there was no evidence of HHV-8 and EBV DNA sequences and we were not able to find cyclin 1 overexpression.