Brain Pathology Case of the Month - October 2013

Contributed by Jantima Tanboon, MD1; Taweesak Aurboonyawat, MD2; Orasa Chawalparit, MD3
    1Department of Pathology
    2Division of Neurosurgery, Department of Surgery
    3Department of Radiology
     Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand


A 26-year-old man presented with a 1 year history of memory impairment. He became somnolence and lethargy 8 months before seeking medical attention. He needed to sleep over 20 hours per day. The physical examination and neurological examination were unremarkable.


Brain MRI revealed a 5.7x4.3x4.2 cm in the 3rd ventricle with isosignal intensity on T1W, heterogeneous signal on T2W and FLAIR (not shown). The mass showed intense heterogeneous enhancement on T1W after gadolinium injection. Extension to the suprasellar cistern was demonstrated on sagittal T1W after gadolinium injection (Figure1). There was also thickening and enhancement of the pituitary stalk, suggestive involvement or origin of hypothalamus. The coronal T1W after gadolinium injection showed separation of the mass from lateral ventricle (Figure 2). The inferior wall of the lateral ventricle displaced upward as well as the septum pellucidum.


The patient underwent biopsy and later bifrontal craniotomy for tumor removal. Intraoperatively, the tumor appeared white and had rubbery to hard consistency. It located at the 3rd ventricle adhering to lamina terminalis and both thalamus. There was low tumor vascularization. The tumor was totally resected. Postoperatively, the patient developed transient diabetes insipidus. There was no evidence of tumor recurrence on follow up MRI after 9 months of surgery.


Intraoperative squash preparation showed hypercellular smear with epithelioid nests, discohesive cells, and 3D papillary-like fragments (Figure 3). The epithelioid cells contained moderate amount of eosinophilic cytoplasm. They were relatively uniform and possessed round to oval, central or eccentric nuclei, with open chromatin and small nucleoli (Figure 4). The discohesive cells had delicate cytoplasmic process and show similar nuclear features (Figure 5). Permanent section revealed a well demarcated mass composed of clusters and cords of epithelioid cells in a myxoid stroma with scattered lymphoplasmacytic infiltration (Figure 6, Figure 7). Rosenthal fibers are observed in adjacent brain parenchyma (Figure 6). Mitotic figure, necrosis and vascular proliferation were not present. Higher magnification showed mild variation (Figure 8) epitheliod cells with moderate to ample amount of eosinophilic cytoplasm in a myxoid stroma. Findings on nuclear detail were similar to those present in squash cytology. Immunohistochemically, the tumor cells were diffusely positive to GFAP (Figure 9), and vimentin (not shown). Focal positivity to CD34 was noted (Figure 10). Staining for S-100 protein and EMA were negative (not shown). Ultrastructural study on specimen retrieved from paraffin-embedded tissue revealed microvilli (Figure 11) at the luminal surface, and intermediate junctions (not shown). The cytoplasm contained mitochondria, ribosome, lysosome, and dilated rER. Intermediate filaments (Figure 12) in the cytoplasm of many tumor cells are noted. What is your diagnosis?


International Society of Neuropathology