Intranodal palisaded myofibroblastoma: a case report and an update on etiopathogenesis and differential diagnosis.

Intra-nodal palisaded myofibroblastoma (IPM) is a rare benign lymph node mesenchymal tumor. It presents as a slow growing, painless nodular mass confined mostly to the inguinal area. Histologically, it shows palisading spindle cells, hemorrhages, hemosiderin laden macrophages, and amianthoid fibers, almost totally replacing the lymph node. Recent genetic evidence supports viral etiology. A case of IPM occurring in a 25-year-old woman is presented and the differential diagnosis of this lesion is discussed. IPM occurs between 4 th and 6 th decade of life, male to female ratio is 2:1 and the inguinal region is the commonest location. Origin of this tumor is from myofibroblasts or smooth muscle fibers. Though benign, morphologically it can be confused with malignant tumors like Kaposi's sarcoma, melanoma, and leiomyosarcoma. Prognosis is excellent and surgical excision is the only needed treatment. There are no reports of malignant transformation though an occasional case has recurred.