Brain Pathology Case of the Month - August 2012

Contributed by Yong Huang, MD, Juan Quan, MD, Hong Su, MD, Hai-xia Hu, MD, Feng Wang, MD
Department of Pathology, 251 Hospital, People's Liberation Army (PLA), Zhangjiakou, China


CLINICAL HISTORY AND IMAGING STUDIES

A 40-year-old female presented with new-onset seizures 4 months ago and with a menstrual disorder for the past 2 months. She was admitted to our hospital for evaluation. Physical examination was non-specific. MRI of the brain revealed a well-delineated homogeneously contrast-enhancing mass in the posterior lobe of the hypophysis. No abnormal signal was found in brain parenchyma. Serum levels for LH, FSH and prolactin were within normal limits as were progesterone and estrogen. MRI demonstrated a sellar mass measuring about 3.63.5 mm in size. The lesion was generally isointense to gray matter on T1-weighted images (Figure 1) and isointense to slightly hyperintense on T2-weighted images (Figure 2). The patient was diagnosed with a presumed pituitary microadenoma and epilepsy, and an endoscopic transphenoidal resection was performed.

GROSS AND MICROSCOPIC PATHOLOGY

On endoscopic view, a gray-white, well circumscribed intrasellar mass was found. The tumor appeared soft and did not adhere to the optic chiasm. Microscopically, the tumor consisted of a sheets of spindled cells arranged in interlacing fascicles and bundles (Figures 3 and 4). The tumor had fibrillar cytoplasm and slightly pleomorphic nuclei that were oval and elongated with small nucleoli. There were no Rosenthal fibers, granular eosinophilic bodies, or Herring bodies. Mitoses were absent. MIB-1 proliferation index was very low (<1%, Figure 5). There was no endothelial proliferation or necrosis. The tumor cells exhibited strong immunoreactivity for S100 protein (Figure 6), patchy staining for glial fibrillary acidic protein (GFAP, Figure 7) and Epithelial Membrane Antigen (EMA, Figure 8). The tumor was negative for Progesterone Receptor and Neu-N.

FINAL DIAGNOSIS


International Society of Neuropathology