PMC9282777_01
Preoperative and postoperative imaging of the pineal region neoplasm. (a) Axial T1-weighted MRI shows a mass, measuring 3.0 x 2.1 cm, at the level of the pineal gland with heterogeneous, mostly solid enhancement. (b) Axial T1-weighted MRI after resection reveals minimal linear enhancement along the margin of the surgical cavity.
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F1
Brain MRI showed a 3.0 x 2.1 cm heterogeneously enhancing mass in the pineal region [Figure 1a]. A gross total resection of the tumor was performed [Figure 1b].
Histologic features of the pineal region neoplasm. (a) Hematoxylin and eosin-stained sections of the resection specimen show a pleomorphic neoplasm with thick, fibrillary, cytoplasmic processes. Some cells have ovoid nuclei, and some have spindle-shaped nuclei. (b) Eosinophilic granular bodies and Rosenthal fibers are noted on a frozen section. Low magnification (c) and high magnification (d) photomicrographs reveal many ganglioid cells with prominent nucleoli. (e) Collections of mixed chronic inflammatory cells can be seen around some blood vessels. (f) Tumor cells are present adjacent to hyalinized blood vessels and corpora arenacea.
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F2
Hematoxylin and eosin-stained sections of the resection specimen showed highly pleomorphic tumor cells, with large ganglioid cells containing vesicular nuclei and distinct nucleoli interspersed between variably sized ovoid cells and spindle-shaped bipolar cells containing fibrillary, eosinophilic cytoplasmic processes [Figure 2a]. Scattered Rosenthal fibers and eosinophilic granular bodies were present [Figure 2b]. A subset of the ganglioid cells were binucleated or multinucleated [Figures 2c and d]. Areas of perivascular inflammation [Figure 2e], vascular hyalinization [Figure 2f], and corpora arenacea [Figure 2f] were noted.
Immunophenotype and EGFR gene copy number of the pineal region neoplasm. (a) GFAP immunoreactivity is diffusely positive in the glial component. (b) Olig2 is expressed in the majority of cells. (c) A phosphorylated neurofilament immunostain highlights many tumor cell axons. (d) Granular synaptophysin immunoreactivity, including in the soma and axons of a gangliocytic tumor cell (arrow). (e) CD34 is positive in a subset of tumor cells with highly branched morphology and in blood vessels. (f) Evaluation of EGFR (black) and chromosome 7 (CEP7 probe, red) through silver in situ hybridization shows chromosome 7 polysomy without selective EGFR amplification.
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F3
Glial fibrillary acidic protein (GFAP) immunoreactivity was diffusely positive in the glial component [Figure 3a] and a subset of the gangliocytic and multinucleated cells, and OLIG2 was expressed in the majority of tumor cells [Figure 3b]. Phosphorylated neurofilament [Figure 3c] and granular synaptophysin immunoreactivity, including in the somata and axons of some gangliocytic tumor cells [arrow, Figure 3d], confirmed that the tumor was a ganglioglioma. Highly branched CD34-positive cells, present in the majority of gangliogliomas, were abundant [Figure 3e]. To begin to evaluate the molecular alterations in this tumor, paraffin-embedded sections were incubated with chromosome 7 reference alpha-centromeric (CEP7, red) and EGFR (black) in situ hybridization DNA probes [Figure 3f].