Brain Pathology Case of the Month - October 2010

Contributed by Mary Ann Sanders, M.D.,Ph.D., Todd Vitaz, M.D.*, Marc Rosenblum, M.D†.,
     Alexis R. Plaga*, Joseph C. Parker, Jr., M.D., and John R. Parker, M.D.
Department of Pathology and Laboratory Medicine, University of Louisville, Louisville, Kentucky;
     Norton Neuroscience Institute*, Louisville, Kentucky; and Department of Pathology†, Memorial Sloan-Kettering,
     New York, New York.


A 46-year-old man presented with a 2 week history of bilateral lower extremity numbness and tingling. The patient had a past medical history significant for a right posterior fossa medulloblastoma diagnosed at the age of 24, treated with total resection and craniospinal radiation (5040 cGy to the posterior fossa, 3960 cGy to the whole brain, and 3420 cGy to the spine). Twenty-one years later, at the age of 45, the patient experienced progressive right lower extremity weakness and subsequent MRI showed an expansile intradural extramedullary enhancing 1.3 cm T5 level spinal cord lesion. This lesion was presumed to be recurrent medulloblastoma in the form of drop metastasis, and the patient underwent additional radiation to the tumor and a small surrounding margin (3750 cGy). Several months after treatment, at the age of 46, the patient experienced recurrent symptoms of lower leg weakness. A follow-up MRI revealed a 1.4 cm intradural extramedullary lesion at T7 with associated cord edema. Sagittal sequences performed after the administration of intravenous gadolinium chelate demonstrated subtle enhancement (Figure 1). In an effort to confirm the diagnosis of recurrent meduloblastoma and rule out radiation necrosis or a second malignancy as well as to help determine future treatment it was determined that histological confirmation was necessary. The patient underwent an uneventful thoracic laminectomy at T6-T7 with subtotal resection of the intradural lesion.


Resection of the spinal tumor showed a hypercellular neoplasm (Figure 2) with some areas showing cells situated in cords and other areas showing a vague nodular appearance corresponding with decreased reticulin staining (Figure 3). Tumor cells were small and displayed densely hyperchromatic nuclei with nuclear molding and appeared to form suggestive Homer-Wright rosettes (Figure 4). Occasional mitotic figures and apoptotic nuclei were noted. Immunohistochemistry showed positive but patchy synaptophysin staining (Figure 5) and strong, perinuclear GFAP staining in many neoplastic cells (Figure 6). Additionally, areas of the tumor displayed a synaptophysin positive fine matrix. Ki-67 labeled approximately 30% of neoplastic nuclei. Tumor cells were negative for CAM 5.2, neurofilament, CD3 and CD20 expression.


International Society of Neuropathology