PMC8720422_01
Brain MRI with and without contrast demonstrated a 4.2 cm lobulated, enhancing mass in the right inferior frontal lobe with extensive surrounding edema. The mass appears hypointense on the T1-weighted MRI non-contrast sequence (a) with diffuse enhancement on the post-contrast sequence (b). The extent of edema is noted on T2-weighted (c) and T2/FLAIR (d) images.
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F1
T1-weighted MRI sequence showed a hypointense mass [Figure 1a] with diffuse enhancement on the post-contrast sequence [Figure 1b]. The T2 MRI sequence showed heterogeneous cystic and necrotic areas [Figure 1c]. FLAIR signal abnormality demonstrated extensive surrounding edema involving the right frontal, parietal, and temporal lobes [Figure 1d].
Pathology revealed a well marginated neoplasm composed of lobules of round to spindle-shaped cells arranged in nests and cords among a myxoid and collagenous matrix surrounded by a peripheral rim of bone. Hematoxylin and eosin staining demonstrating lobules of spindle-shaped cells (x20) (a). Strong, diffuse immunohistochemical staining for vimentin (x20) (b). Diffuse immunohistochemical staining for CD56 (x20) (c).
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F2
Final pathology showed a non-infiltrating neoplasm composed of lobules of round to spindle-shaped cells arranged in cords among a myxoid and collagenous matrix [Figure 2]. CD56, neurofilament, desmin, and vimentin were among the immunohistochemical markers demonstrating strong positivity [Table 1] and [Figure 2].
The planning target volume (PTV) (100% of the dose was prescribed to this volume) consisted of the resection cavity (outlined in orange) plus a 3 mm margin (outlined in red) as identified on the T1 post-contrast sequence (a). A 3-arc VMAT plan with 6 megavoltage photons shows the 100% isodose line (21 Gy) covering the PTV target (resection cavity + 3mm margin) on the planning CT head (b).
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F3
T1 post-contrast volumetric sequence for better depiction of the resection cavity. The planning target volume (PTV, volume to where 100% of the dose was prescribed) consisted of the resection cavity plus a 3-mm margin to account for errors during planning and treatment delivery [Figure 3a]. Plan review ensured that 95% of the planning target volume was covered by the total dose of 21 Gy (100% isodose line) [Figure 3b].