CT and pathologic findings of a case of subdural osteoma

Subdural osteoma in an adolescent patient with epilepsy: an unusual case report and literature review

OBJECTIVE

Subdural osteoma (SO) is a rarely reported benign tumor, and there is no report of SO manifested with epileptic seizures. We aim to further the understanding of SO-related epilepsy.

METHODS

Here, we report a meaningful case of epilepsy secondary to SO. A systematic review of the literature about SO using the electronic database PubMed and Web of science up to December 2022 was conducted.

RESULTS

A 15-year-old girl presented with epileptic seizures for 8 years. Magnetic resonance imaging revealed an irregular lesion with heterogeneous signal in the right frontal convexity. Right frontal craniotomy was performed to remove the lesion. The pathological diagnosis was SO. Histological analysis revealed that the mechanosensitive ion channels Piezo 1/2 were upregulated in the brain tissue compressed by the osteoma, compared with the levels in the osteoma-free region. Seizure freedom was obtained during the 6-month follow-up after the surgery. We identified 24 cases of SO in 23 articles. With our case, a total of 25 cases with 32 SOs was included. Of 25 cases, 24 are adults, and 1 is a child. Seizure has been reported only in our case. Frontal osteoma was found in 76% of the patients. Symptoms were cured in 56% of the patients after surgery.

CONCLUSION

Surgery is a safe and effective approach to the treatment of symptomatic osteoma. Mechanical compression on cerebral cortex may be a predisposing factor of the epileptogenesis caused by the SO.

Solitary subdural osteomas: Systematic review of the literature with an illustrative case

Background

Subdural osteomas represent an extremely rare entity with only 20 cases described to date. Despite the typical benign behavior, these tumors can grow to compress the brain and occasionally detach from the dura mater.

Methods

A systematic search of the literature was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. After screening for duplicates, 179 publications met the eligibility criteria. Finally, 18 manuscripts were included in this review. Moreover, a detailed description of an illustrative case is provided.

Results

The median age at diagnosis was 43.2 years, showing a female prevalence. The inner table of the frontal bone was reported as the most frequent location, and in six cases, the lesions did not show any relation with the dura, which appeared intact. Surgical resection appears to be an effective and safe management option. In the present work, the case of a 60-year-old female who presented with persistent, diffuse headaches which had first occurred 6 months earlier is described. On admission, the physical and neurological examinations were unremarkable, and her medical history disclosed no systemic disease, meningitis, or head injury. Computed tomography showed a homogeneous, high-density nodule attached to the inner table of the left middle cranial fossa.

Conclusion

In addition to an in-depth case description, the first systematic and qualitative review of the literature on intracranial subdural osteomas using the PRISMA is provided.

A Rare Occurrence of Multiple Intracranial Osteomas in the Cranial Cavity of a Cadaver With a Short Review on Subdural Osteoma

Osteomas are most common among all primary bone tumors of skull bones. They are usually asymptomatic due to their small size and slow growth. They are found incidentally on imaging studies for other neurologic symptoms. Osteoma may be single or multiple when present. They should be differentiated from meningiomas, chordomas, schwannomas, and parosteal osteosarcoma by using different diagnostic methods, including histopathologic study.

During routine dissection for MBBS students in an 87 years old female cadaver, we found multiple (seven in number) irregular, lobulated bony masses/structures. Their positions were different with respect to the layers of meninges. Some were present between the dura mater and arachnoid mater compressing the adjacent brain tissues forming impressions on them, and some were outside the dura mater. So, into the previously existing classification, we want to add a new variety under the type b category, i.e., mixed type (intraparenchymal, dural, skull vault) as pointed under the subtype V, which is found in our case.

Skull Imaging-Radiographs and CT revisited

Although rare, skull vault lesions include a vast array of pathology encompassing infection, benign, and malignant bone tumors. Given the large range of potential diagnoses, it is crucial to identify imaging features to differentiate one from another, ensuring early diagnosis. Radiographs are still valuable in modern radiology but have largely been superseded by computed tomography (CT) due to its high spatial resolution. Both are especially important in developing countries where access to magnetic resonance imaging (MRI) may be limited.There are currently several publications outlining imaging appearances of skull vault lesions. However, the majority of literature is dated, with the last dedicated textbook published in 1980 (Principles of X-ray diagnosis of the skull). Despite overlapping features, a few lesions have "aunt minnie," type classical characteristics, which we will highlight. Most vault lesions also appear as a spectrum depending on location and the exact stage of the disease. A small subset within each disease entity also has atypical features not widely discussed in the current literature. In this pictorial review, we hope to focus on radiographic and CT imaging appearances to help differentiate between various skull vault lesions.

Intradural osteomas: Report of two cases

BACKGROUND

Intradural osteoma is very rarely located in the subdural or subarachnoid space. Unfortunately, intradural osteoma lacks specificity in clinical manifestations and imaging features and there is currently no consensus on its diagnosis method or treatment strategy. Moreover, the pathogenesis of osteoma without skull structure involvement remains unclear.

CASE SUMMARY

We describe two cases of intradural osteomas located in the subdural and subarachnoid spaces, respectively. The first case involved a 47-year-old woman who presented with a 3-year history of intermittent headache and dizziness. Intraoperatively, a bony hard mass was found in the left frontal area, attached to the inner surface of the dura mater and compressing the underlying arachnoid membrane and brain. The second case involved a 56-year-old woman who had an intracranial high-density lesion isolated under the right greater wing of the sphenoid. Intraoperatively, an arachnoid-covered bony tumor was found in the sylvian fissure. The pathological diagnosis for both patients was osteoma.

CONCLUSION

Surgery and pathological examination are required for diagnosis of intradural osteomas, and craniotomy is a safe and effective treatment.

Surgical case of intracranial osteoma arising from the falx

Intracranial osteomas completely unrelated to osseous tissues are extremely rare. In the present study, the case of a 40-year-old female who presented with persistent headache is reported. Computed tomography (CT) and bone window CT revealed an ossified lesion in the frontal area. Fast imaging employing steady-state acquisition (FIESTA)/CT venography fusion imaging demonstrated that the mass was located just below the superior sagittal sinus and cortical veins, and had adhered partially to these veins. Surgery achieved complete tumor removal with preservation of the cortical veins and superior sagittal sinus. The histological examination findings were compatible with osteoma. The present postoperative course was uneventful. The present rare case of intracranial osteoma originating from the falx was successfully treated surgically. Preoperative FIESTA/CT venography fusion imaging was very useful to demonstrate adhesion between the tumor mass and the superior sagittal sinus and cortical veins.

Solitary subdural osteoma: A case report and literature review

Osteomas attached to the meninges unrelated to bone are extremely rare and their etiology has not been discussed previously in the English literature. Here, we report the case of a 54-year-old male patient with a right frontal subdural osteoma. The patient presented with a ~5-month history of intermittent dizziness. Non-contrasted computerized tomography demonstrated a densely calcified mass attached to the inner surface of the right frontal skull. Magnetic resonance imaging (MRI) revealed this mass could be enhanced by contrast MRI. Intraoperatively, the hard mass was noted to be attached to the inner layer of the dura mater, and not associated with the bone. Histopathological examination revealed lamellated bony trabeculae lined by osteoblasts and the intertrabecular marrow spaces occupied by adipose tissue, which contributed to the MRI enhancement. It was speculated that subdural osteomas arose from ectopic osteoblasts derived from the embryological neural crest cells. The context of intertrabecular bone marrow contributed to the enhancement on MRI. Simple excision is the treatment of choice for symptomatic lesions.

Clinical, Radiologic, and Pathologic Findings of Subdural Osteoma: A Case Report

We present a case of a subdural osteoma. A 29-year-old female presented with a 3-year history of headaches. Computed tomography scan revealed a homogeneous high-density lesion isolated from the inner table of the frontal bone (a lucent dural line) in the right frontal convexity. Magnetic resonance imaging revealed an extra-axial lesion with a broad base without dural tail sign and punctate enhancement pattern characteristic of abundant adipose tissue. Upon surgical excision, we found a hard bony mass clearly demarcated from the dura. The mass displayed characteristics of an osteoma upon histological examination. The symptom was relieved after operation.

Multiple osteomas of the falx cerebri and anterior skull base: case report

The authors describe a rare case of intracranial extraaxial parafalcine and anterior skull base osteomas in a 22-year-old woman presenting with bifrontal headaches. This case highlights the possible occurrence of such lesions along the anterior skull base and parafalcine region that, as such, should be considered as part of the differential diagnosis for extraaxial calcific lesions involving the anterior skull base. To the authors' knowledge, this is the first reported case of a patient who underwent complete successful resection of multiple extraaxial osteomas of the anterior skull base and parafalcine region.

Solitary intracranial osteoma with attachment to the falx: a case report

Background

Intracranial osteomas are uncommon lesions that usually arise from the inner table of the cranium. There are few reports in the literature of intracranial osteomas with meninges attachment and without direct relation with the skull bone; these osteomas were mostly attached with dura. We report a rare osteoma with falx attachment.

Case

A 64-year-old woman presented with a 3-month history of intermittent tinnitus and dizziness. The scout film of petrous bone computed tomography scan revealed a high-density lesion in the frontal area. Magnetic resonance imaging showed a 2.5-cm mass attached to the surface of the falx in the right frontal parasagittal area. The patient underwent right frontal craniotomy, and a bony hard mass was found located in the right frontal parasagittal region extra-axially, with its medial surface attached to the falx. It could not be broken down by the cavitron ultrasonic surgical aspirator or even the cutting loop and was detached from the falx and removed in one piece. Histopathological examination showed a nodule with bony trabeculae and bone marrow tissue, compatible with osteoma. The postoperative course was uneventful, and the patient was discharged from the hospital with no neurological deficits one week after operation.

Conclusions

This is the first case report in the English literature of an intracranial osteoma arising from the falx. Because of their slow growth and their locations in silent brain areas, intracranial osteomas are usually diagnosed incidentally. Surgical resection is the primary treatment choice.

Intracranial subdural osteoma: a rare benign tumor that can be differentiated from other calcified intracranial lesions utilizing MR imaging

We report the magnetic resonance (MR) imaging characteristics of subdural osteoma and other benign calcified intracranial lesions to highlight imaging features that differentiate between these disease entities. A 63-year-old woman presented with progressively altered mental status. Non-contrast CT demonstrated a densely calcified right middle cranial fossa extra-axial mass. MR imaging of the lesion demonstrated T1 and T2 hypointensity without evidence of contrast enhancement, parenchymal abnormality, or connection to adjacent venous structures. Diffusion weighted imaging demonstrated markedly decreased signal intensity and artificially reduced diffusion on apparent diffusion coefficient map. Histologically, the tumor was predominantly composed of lamellar bone and small fragments of residual dura consistent with subdural osteoma. This case demonstrates that radiological examination can provide additional insight into the origin of intracranial osteomas (extradural versus subdural versus sinonasal) and help distinguish from other diagnostic considerations including benign meningeal ossification and calcified meningioma prior to surgical resection.

Description of a Cranial Endocast from the Fossil MammalVincelestes neuquenianus (Theriiformes) and its Relevance to the Evolution of Endocranial Characters in Therians

We generated a digital cranial endocast (infilling of the braincase) of Vincelestes neuquenianus, a Cretaceous theriiform mammal from Argentina, to achieve two goals. First, we described this endocast of Vincelestes to reconstruct the brain, associated soft-tissue structures, and internal osteological features. This report represents the first description of an endocast from a stem therian that is near crown group Theria (marsupials, placentals, and all descendants of that ancestor). Second, we examined 21 morphological characters related to the morphology of endocasts and endocranial osteology across 19 taxa (including Vincelestes) in the context of a current hypothesis about mammal phylogeny to identify potential synapomorphies for Theria. The digital endocast of Vincelestes is mostly complete, facilitating description in all views and allowing collection of accurate linear and volumetric measurements. However, it is unclear if the midbrain is exposed on the dorsal surface of the brain because of damage to this region of the endocast. Other portions of this specimen are extraordinarily well preserved, allowing identification of the accessory olfactory bulbs on the endocast, an ossified falx cerebri, and an osseous tentorium. The encephalization quotient (EQ) calculated for Vincelestes falls within the range of EQs of crown therians. Comparison of the endocranial characters across different mammalian taxa did not reveal any new synapomorphies for the clade Theria.