GIANT-CELL FIBROBLASTOMA - NEW HISTOLOGICAL OBSERVATIONS

Giant cell fibroblastoma is a rare mesenchymal neoplasm of unknown ori gin and uncertain clinical course. The neoplasm has been considered by some authors as a juvenile variant of dermatofibrosarcoma protuberans . We report a patient with giant cell fibroblastoma, now 28 months fol lowing surgical removal, in which the neoplasm was characterized histo logically by a proliferation of spindle-shaped cells intermixed with p seudovascular channels called ''angiectoid spaces.'' The spaces were l ined by large cells with pleomorphic nuclei intermixed with multinucle ated cells. Immunohistochemically, the tumor stained diffusely for vim entin and CD34, a surface glycoprotein expressed by some mesenchymal n eoplasms including dermatofibrosarcoma protuberans. We postulate a mec hanism of formation of the angiectoid spaces based on histopathologica l findings in serially sectioned portions of the neoplasm. Positive st aining of tumor cells for CD34 supports a possible relationship of the neoplasms with dermatofibrosarcoma protuberans.