PMC8769392_01
(A and B) CT 5 years before operation. An intradiploic bone lesion in the right frontal bone was incidentally detected. (C and D) Preoperative CT showing a cystic lesion with bone destruction. (E and F) Preoperative MRI. (E) Contrast-enhanced T1-weighted imaging shows a slight enhancement in the cyst wall. (F) T2-weighted imaging shows a homogeneous signal intensity within the lesion. CT: computed tomography, MRI: magnetic resonance imaging.
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F1
The patient was a 79-year-old woman who was diagnosed with vertigo and was identified as having a right frontal bone lesion (Fig. 1A and 1B). The bony structure of the lesion had disappeared, and dissociation between the inner and outer plates was observed in some sections (Figs. 1C and 1D). The border of the dura mater was not clear (Figs. 1E and 1F).
(A-E) Intraoperative photographs. (F) Postoperative MRI. Histopathological findings of the resected tumor. (G-I) Hematoxylin and eosin staining. (J) Ki67 staining. (A) The skin flap was everted, leaving a periosteum on the surface of the tumor. (B) The surrounding bone was resected in the shape of a doughnut. (C) The tumor was resected together with the dura mater. (D) Dura mater side of the resected tumor. No macroscopic tumor infiltration was found on the inner surface of the dura mater. (E) Duraplasty was performed with artificial dura mater, and cranioplasty was performed with artificial bone. (F) No residual lesions is observed. (G) Cross-section of the entire cyst. The cyst wall is composed of fibrous connective tissue. Original magnification: x10. Scale bar: 4 mm. (H) The site indicated by the box in G. Highly atypical cells and intratumoral hemorrhage suggesting malignancy are observed. Original magnification: x200. Scale bar: 100 mum. (I) The highly magnified picture of H. Nuclei of atypical cells are irregular and different in size, and nucleoli of them are enlarged. Original magnification: x400. Scale bar: 50 mum. (J) The septum of the cyst in another section. Atypical cells with osteogenic properties are observed in other sections. Original magnification: x200. Scale bar: 100 mum. MRI: magnetic resonance imaging.
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F2
A loose connective tissue layer beneath the galeal aponeurosis was dissected, and the flap was everted, leaving a periosteum on the surface of the tumor (Fig. 2A). A navigation system confirmed the range of normal bone tissue, and the surrounding bone was resected in the shape of a doughnut (Fig. 2B). With the surrounding normal dura mater roundly incised, the tumor was resected together with the dura mater (Fig. 2C). There was no macroscopic tumor infiltration on the inner surface of the dura mater (Fig. 2D). Duraplasty was performed with an artificial dura mater, and cranioplasty was performed with an artificial bone (Fig. 2E). Postoperative MRI showed no evidence of residual lesions (Fig. 2F). The content was mainly red blood cells; there were no skin appendages and keratinized tissues (Fig. 2G). Subsequent histopathological examination revealed that there were highly atypical cells with intratumoral hemorrhage in some sections (Fig. 2H and 2I) and atypical cells showing osteogenic properties in other sections (Fig. 2J).