SOLITARY FIBROUS TUMOR OF THE MENINGES OCCURRING AFTER IRRADIATION OFA MIXED GERM-CELL TUMOR OF THE PINEAL-GLAND

Twenty-nine months after surgery, irradiation, and systemic chemothera py for a pineal mixed germ cell tumor, an 11-year-old Caucasian male d eveloped a 3 cm dural based nodule in the occipital lobe that proved t o be a solitary fibrous tumor by immunohistochemical and ultrastructur al examination. Differential diagnosis included fibrous meningioma, ne urofibroma, Schwannoma, cranial fasciitis of infancy, and solitary fib rous tumor. A Masson trichrome stain revealed a prominent collagenous stroma and reticulin staining exhibited strong pericellular positivity . Immunohistochemical staining demonstrated diffuse vimentin and focal CD34 positivity of tumor cells. Ultrastructural examination revealed fibroblastic differentiation. These features are consistent with solit ary fibrous tumor. Although we favor a radiation-induced origin for th e neoplasm, alternative explanations for the tumor's origin include ce rebrospinal fluid spread from the original germ cell tumor or a de nov o neoplasm.