Brain Pathology Case of the Month - February 2007

Contributed by Terri Haddix, MD, Steven Chang, MD and Hannes Vogel, MD
Stanford University Medical Center, Departments of Pathology (Neuropathology) and Neurosurgery


A 35-year-old woman presented for neurological evaluation after a single episode of speech disruption consisting of word finding difficulty and a partial motor seizure followed by one hour of confusion. A head MRI scan was performed, which showed a 2.7 by 2.0 by 2.5 cm dural-based contrast enhancing lesion along the left posterior temporal lobe (Figure 1). An EEG at the time of presentation was negative, but the patient was placed on prophylactic Dilantin therapy. She was referred for neurosurgical evaluation, and a recommendation was made for surgical resection. A left parietal-temporal craniotomy was performed to resect the tumor. At surgery, a firm dural-based lesion was encountered with no evidence of brain invasion or involvement, and a gross total resection was performed. The patient tolerated the procedure well, and was discharged home on postoperative day three. The patient had no further seizures or episodes of speech difficulty, and was tapered off of her anticonvulsants six months following surgery, with a second EEG negative at that time. Follow-up MRI scans at 6 and 12 months showed no evidence of tumor recurrence, and she continues to have a normal neurological exam.


Macroscopically, the resected tumor was spherical, tan-pink, homogeneous and 2 cm in diameter. A piece of dura was adherent to one side. A cytologic preparation only was utilized for the intraoperative pathologic consultation, which demonstrated a moderately pleomorphic population of cells, primarily in clusters; no distinct whorls nor psammomatous calcifications were seen. Many of the cells had prominent eosinophilic cytoplasm and occasional intranuclear pseudoinclusions were found. In consideration of the radiographic appearance and the cytologic appearance, the intraoperative pathologic diagnosis was meningioma. The permanent sections of the tumor specimen demonstrated a well-demarcated pleomorphic dural-based tumor (Figure 2). Many of the cells had large, pleomorphic and often vacuolated nuclei. In some regions, fascicles of more spindled appearing cells predominated. Whorls of reactive meningeal cells were focally noted at the edges of the tumor-dura interface. Within the tumor, collections of xanthomatous cells and numerous eosinophilic granular bodies were identified (Figure 3). The majority of the tumor cells were immunopositive for glial fibrillary acidic protein (GFAP) (Figure 4), S-100 (both nuclear and cytoplasmic staining) and vimentin. A subpopulation of the tumor cells was immunoreactive for CD68. The tumor cells were not reactive for synaptophysin, smooth muscle actin, epithelial membrane antigen, pankeratin (AE1/AE3), desmin or alpha-1-antitrypsin. A rich reticulin network surrounding most of the individual tumor cells was highlighted in special stains (Figure 5). There were many scattered collections of small lymphocytes. While a Ki-67 immunostain demonstrated a labeling index of approximately 30%, lymphocytes accounted for the vast majority of the proliferating cells. No regions of necrosis were identified; no mitotic figures were seen in the H & E stained sections.


International Society of Neuropathology