case_images: PMC5025957_01
case_images: (a) Sagittal T1 precontrast, (b) sagittal T1 postcontrast, (c) axial fluid-attenuated inversion recovery
case_images: SNI-7-596-g001.jpg
case_images: PMC5025957_01_SNI-7-596-g001.jpg
case_images: F1
case_images: Magnetic resonance imaging (MRI) with contrast was obtained, revealing a 3.6 x 3.7 x 3.2 cm lobulated, heterogeneous, fluid-attenuated inversion recovery hyperintense, and avidly enhancing hypothalamic mass extending into the anterior third ventricle [Figure 1].
case_images: (a) Hematoxylin and Eosin (H and E), low power, (b) H and E, medium power, (c) H and E, medium power, (d) H and E, medium power, (e) H and E, low power, (f) CD34, (g) CD31, (h) Erg, (i) SMA, (j) EMA, (k) CD163, (l) CD3, (m) CD20, (n) Ki-67, (o) GFAP
case_images: SNI-7-596-g002.jpg
case_images: PMC5025957_01_SNI-7-596-g002.jpg
case_images: F2
case_images: Histologic examination demonstrated a predominantly epithelioid neoplasm with areas of spindled cytology with a dense inflammatory infiltrate [Figure 2a]. The tumor demonstrated several architectural patterns, including retiform [Figure 2b], chordoid [Figure 2c], and strands, often embedded in a myxoid matrix, giving an appearance reminiscent of chordoma at low power. At high power, many cells demonstrated intracytoplasmic lumina [Figure 2d] with occasional erythrocytes. The tumor was sharply demarcated from the surrounding brain, with reactive changes, including gliosis and accumulation of Rosenthal fibers, suggesting slow growth [Figure 2e]. The tumor cells were strongly and diffusely positive for CD34 [Figure 2f], and more focally positive for CD31 [Figure 2g], FLI-1, and factor VIII, compatible with a tumor of endothelial origin; however, there was only scattered reactivity for Erg [Figure 2h]. An immunostain for SMA [Figure 2i] to rule out a fibroblastic process or leiomyosarcoma were negative, and an immunostain for ALK-1 performed to exclude inflammatory pseudotumor was negative. Immunostains for EMA [Figure 2j], progesterone receptor, and S-100 were negative, which are less compatible with diagnoses of chordoid meningioma, chondrosarcoma, and chordoma. Immunostains for CD163, CD3, CD20, and CD68 [Figure 2k-m] highlighted a marked lymphohistiocytic infiltrate throughout the tumor, however, immunostains for CD15 and CD30 were negative, arguing against a lymphoproliferative disease such as Hodgkin lymphoma, and an immunostain for CD1a to exclude a histiocytic process such as Langerhan's cell histiocytosis was negative. Immunostain for Ki-67 shows scattered positivity, demonstrating the moderate proliferative characteristics of this tumor [Figure 2n]. An immunostain for glial fibrillary acidic protein [Figure 2o] is negative in the tumor cells, but highlights the sharp demarcation of the tumor from the adjacent brain.