Giant intraosseous (ectopic) meningioma of the temporoparietal calvarium with rapid expansion over 5 years: A case report.
Intraosseous (ectopic) meningiomas are rare extradural tumors arising within the calvarial bone and account for <1% of all meningiomas. Because their imaging appearance may range from osteolytic to sclerotic or mixed patterns, they can mimic primary bone tumors or metastatic lesions and lead to diagnostic uncertainty.
A 50-year-old woman presented with a gradually enlarging right temporoparietal scalp mass associated with mild headache for 5 years. The lesion caused marked cosmetic asymmetry without neurological deficit.
Serial cranial computed tomography demonstrated an expansile right temporoparietal intraosseous calvarial lesion that enlarged from 5.8 × 5.1 × 1.8 cm in 2019 to 17.6 × 14.3 × 4.4 cm in 2024. The mass showed a heterogeneous mixed osteolytic-sclerotic pattern with diploic expansion, cortical thinning, and irregular inner table extension abutting the dura, without a definite intradural component. Histopathological and immunohistochemical evaluation established the diagnosis of ectopic intraosseous meningioma.
The patient underwent right temporoparietal craniectomy with complete excision of the involved calvarial bone. The dura appeared uninvolved intraoperatively and was preserved.
Postoperative recovery was uneventful, with no neurological deficit and marked cosmetic improvement. Histopathological analysis showed a benign meningothelial neoplasm with epithelial membrane antigen and progesterone receptor positivity and a low Ki-67 labeling index of approximately 1%. At 1-year follow-up, imaging showed no evidence of recurrence or regrowth.
Giant intraosseous meningiomas may demonstrate striking radiologic aggressiveness and rapid calvarial expansion despite benign histology and a low proliferative index. They should be considered in the differential diagnosis of large calvarial masses. Complete surgical excision with preservation of intact dura, when appropriate, may provide favorable early clinical and cosmetic outcomes, although longer follow-up is required to assess long-term tumor control.
A 50-year-old woman presented with a gradually enlarging right temporoparietal scalp mass associated with mild headache for 5 years. The lesion caused marked cosmetic asymmetry without neurological deficit.
Serial cranial computed tomography demonstrated an expansile right temporoparietal intraosseous calvarial lesion that enlarged from 5.8 × 5.1 × 1.8 cm in 2019 to 17.6 × 14.3 × 4.4 cm in 2024. The mass showed a heterogeneous mixed osteolytic-sclerotic pattern with diploic expansion, cortical thinning, and irregular inner table extension abutting the dura, without a definite intradural component. Histopathological and immunohistochemical evaluation established the diagnosis of ectopic intraosseous meningioma.
The patient underwent right temporoparietal craniectomy with complete excision of the involved calvarial bone. The dura appeared uninvolved intraoperatively and was preserved.
Postoperative recovery was uneventful, with no neurological deficit and marked cosmetic improvement. Histopathological analysis showed a benign meningothelial neoplasm with epithelial membrane antigen and progesterone receptor positivity and a low Ki-67 labeling index of approximately 1%. At 1-year follow-up, imaging showed no evidence of recurrence or regrowth.
Giant intraosseous meningiomas may demonstrate striking radiologic aggressiveness and rapid calvarial expansion despite benign histology and a low proliferative index. They should be considered in the differential diagnosis of large calvarial masses. Complete surgical excision with preservation of intact dura, when appropriate, may provide favorable early clinical and cosmetic outcomes, although longer follow-up is required to assess long-term tumor control.