case_images: PMC11756955_01
case_images: Case presentation. (
  A
  ) Preoperative magnetic resonance imaging (MRI) scan, T1 contrast-enhanced. (
  B
  ) Preoperative computed tomography (CT) scan. (
  C
  ) Surgical site showing the outline of the osteoclastic craniotomy. (
  D
  ) Surgical site highlighting the dural involvement. (
  E
  ) Postoperative MRI, T1 contrast-enhanced. (
  F
  ) Postoperative CT scan. (
  G
  ) Positioning of the manufactured implant in situ. (
  H
  ) Postoperative photography of the patient depicting the harmonic skull silhouette after a custom-made bone implant.
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case_images: PMC11756955_01_10-1055-a-2508-0868-i24sep0055-1.jpg
case_images: FI24sep0055-1
case_images: A month later, a magnetic resonance imaging (MRI) scan aimed at characterizing the lesion indicated an alarming size increase of the tumor, now measuring 64 x 54 x 47 mm leading to a significant mass effect and cerebral midline shift of almost 10 mm ( Fig. 1A ). After mobilization of the skin, the exophytic tumor mass was clearly identified ( Fig. 1C ). As the dura was macroscopically invaded by the tumor, it was resected by a circular cut along the craniotomy outline ( Fig. 1C ). After the implant had cooled down, it was extracted from the mold and prepared for implantation ( Fig. 1G ).
case_images: Manufacturing of the cranioplasty implant. (
  A
  ) Exophytic growth of the tumor shown on a three-dimensional (3D) volume rendering of the cranial computed tomography scan. (
  B
  ) Virtual planning of the craniotomy outline. (
  C
  ) Exemplary picture of the 3D printing process of the craniotomy template. (
  D
  ) Depiction of the 3D-printed craniotomy template, craniotomy molds, and a skull for preoperative testing. (
  E
  ) Preparation of the cranioplasty molds using a sterile drape and fatty gauze. (
  F
  ) Manufacturing of the tailored cranioplasty implant from polymethylmethacrylate using the patient-specific mold.
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case_images: PMC11756955_01_10-1055-a-2508-0868-i24sep0055-2.jpg
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case_images: Then, the 3D-printed cranioplasty mold was also draped in a sterile film ( Fig. 2E ). The cranioplasty implant was then formed under moderate pressure using the upper part of the mold ( Fig. 2F ). Angeles, California, United States) for further editing. A virtual craniotomy with a safety margin of 10 mm was performed around the depicted lesion ( Fig. 2B ). Both the mold and template were then 3D printed using a PLA (Ultimaker, Geldermalsen, The Netherlands) on an Ultimaker 3 (Ultimaker, Geldermalsen, The Netherlands) FDM 3D printer ( Fig. 2C, D ). 
case_images: Morphological appearance of the tumor. (
  A
  ) Hematoxylin and eosin (H&E) staining:a solid growing tumor, forming osteoid (arrow) with partially sinusoidally dilated blood vessels with a single layer of endothelial cells (arrowhead). (
  B
  ) H&E staining:the osteoid (star) shows signs of calcification in certain regions (arrow) and multinucleated giant cells can be observed (arrowhead). (
  C
  ) H&E staining:mitotic figures frequently appear (arrow). (
  D
  ) K
  i
  -67 immunohistochemistry:a focal proliferation rate of 50%. (
  E
  ) PHH3 immunohistochemistry:up to four mitoses are seen in one high-power field (arrow). (
  F
  ) SATB2 immunohistochemistry:positive labeling of tumor cell nuclei.
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case_images: FI24sep0055-3
case_images: Partially growing into this bone in a cone shape along the marrow spaces, a pleomorphic tumor was observed, partially in larger areas, and partially only in small foci-forming osteoid ( Fig. 3A ). Multinucleated giant cells occurred sporadically ( Fig. 3B ). In other regions, only 20% proliferating nuclei were observed ( Fig. 3D ). Using a PHH3-specific antibody, six mitoses were seen in 10 high-power fields ( Fig. 3E ). In addition, the nuclei were labeled positively with antibodies against SATB2 ( Fig. 3F ).