PMC9062918_01
First resection (H&E, 200x) showing clear cell ependymoma with perinuclear clearing and vague perivascular pseudorosettes.
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F1
The specimen obtained from the initial resection [Figure 1] was formalin fixed, paraffin embedded, and stained with hematoxylin and eosin, as well as the following immunohistochemical stains: GFAP, EMA, progesterone receptor (PR), and phosphohistone H3 (PHH3). Electron microscopy showed poorly formed and ill-defined junctional complexes, but no cilia, microvilli, or dense granules were seen [Figure 1].
Axial T1-weighted imaging post contrast demonstrating (a) focal post-surgical changes from resection twelve years prior and an enhancing cortical lesion within the right parietal lobe concerning for recurrence. (b) immediate post-surgical changes of the right frontoparietal craniotomy for first recurrence with peripheral residual enhancement in resection cavity and mild enhancement in the superior aspect of the frontal lobe.
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F2
Follow-up magnetic resonance imaging (MRI) of the brain identified an enhancing lobulated cortical lesion within her right frontoparietal lobes, in the same location as her original mass that was compressing the primary motor and sensory cortices and extending into the dura [Figure 2a]. The lesion was yellow and well- circumscribed intraoperatively and, following excision, a small rim of residual tumor adherent to the functional cortex remained [Figure 2b].
Second resection (H&E, 100x) showing clear cell ependymoma with perinuclear clearing and vague perivascular pseudorosettes.
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F3
Pathology demonstrated ependymoma with cytomorphologic characteristics similar to her original mass, including clear cells lacking high-grade features [Figure 3].
(a) Second recurrence seventeen months after second resection with interval increased size of right posterior parietal convexity heterogeneously enhancing mass lesion measuring 3.7 x 4.6 x 2.9 cm with additional minimal adjacent nodular enhancement seen within the right superior frontal sulci/gyri and pachymeninges with an increase in associated vasogenic edema (b) Immediate post-surgical changes of right posterior parietal convexity mass resection for second recurrence with irregular brain parenchymal enhancement about the resection site and parietal scalp free flap reconstruction.
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F4
In the same region as her prior tumors, MRI demonstrated a new right posterior parietal convexity, heterogeneously enhancing mass lesion arising along the superior aspect of the resection cavity within the right perirolandic cortex [Figure 4a], as well as multiple surrounding subcentimeter enhancing satellite nodules and a subcentimeter nodule in the corpus callosum. There were also adjacent pachymeningeal enhancement and vasogenic edema with leftward subfalcine herniation [Figure 4a]. Postoperative MRI [Figure 4b] found enhancement along the resection cavity, but no nodular residual lesion was detected, consistent with gross total resection.
Third resection. High-power views of tumor with typical ependymoma features including relatively uniform ovoid cells with perivascular pseudorosettes (a; H&E, 200x) and areas with prominent clear cell change (b; H&E, 200x). Low power views (c-g, 20x) showing large nodules of tumor with clear cell morphology on H&E (c-d). A large nodule with clear cell morphology seen on H&E (d) is strongly positive for synaptophysin (e) and weakly positive for GFAP (f). Ki67 proliferation index is markedly elevated (g). EMA shows characteristic dot-like staining pattern (h; 400x). Transmission electron microscopy of clear cell regions with few poorly-formed intercellular junctions and intracellular glial-type filaments (i; magnification: 2500x).
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F5
Microscopic analysis of the second recurrence [Figures 5a-i] showed regions of tumor with morphological and immunohistochemical features typical of ependymoma, including perivascular pseudorosettes and focal dot-like EMA positivity, as well as malignant features including increased mitotic activity with elevated Ki67 proliferation index, marked hypercellularity, and microvascular proliferation.
Four-month interval development of a solid tumor with a dominant 2.6 x 1.9 cm nodule with additional smaller nodules and right periolandic and deep white matter necrotic bubbly enhancement.
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F6
After another 2 months, the mass had demonstrated rapid growth with significant mass effect as well as necrotic bubbly enhancement of the perirolandic and deep white matter consistent with rapid tumor progression and radiation necrosis, respectively [Figure 6].
Fourth resection showing ependymoma (right half of image) with radiation-associated injury and necrosis of the adjacent brain tissue (left half of image) (H&E, 100x).
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F7
Pathology revealed an ependymal neoplasm and necrosis of brain parenchyma, compatible with radiation necrosis [Figure 7]; given the histomorphologic similarity to the prior specimens, molecular and immunohistochemical testing was not repeated.