Foramina parietalia permagna (FPP) is a rare anatomical defect that affects the parietal bones of the human skull. FPP is characterized by symmetric perforations on either side of the skull, which are caused by insufficient ossification during embryogenesis. These openings are typically abnormally large and can range from a few millimeters to several centimeters in diameter. Enlarged foramina are often discovered incidentally during anatomical or radiological examinations and in most cases left untreated unless symptoms develop. Although this calvarial defect is usually asymptomatic, it may be accompanied by neurological or vascular conditions that can have clinical significance in certain cases. FPP is an inherited disorder and arises due to mutations in either Msh homeobox 2 (MSX2) or aristaless-like homeobox 4 (ALX4) genes. In almost all cases, one parent is affected. Clinical findings and diagnostic imaging typically contribute to determine the diagnosis.

The current study evaluates a rare case of parietal bone osteoid osteoma in pediatrics and review the differential diagnosis of button sequestrum sign in the literature. A 12-year-old girl expressed localized pain in the right parietal bone. MRI represented enhancing nodule with button sequestrum sign appearance.

BACKGROUND: The rare form and mildest variant of Langerhans cell histiocytosis is eosinophilic granuloma (EG). In the clinical presentation, EG can be monostotic, polyostotic, or can encompass many organs. The parietal bone is the most common location of the skull bones that are affected by EG. So far, there have been no reported cases of EG with skull odor as an unexplained presentation.
METHODS: An 8-year-old girl presented with a 4 months history of a right parietal bone swelling of the skull with an offensive odor. There was no discharge and no history of vomiting or trauma. An MRI scan of the brain showed swelling with a bone lesion of the right parietal bone. Infection was the source of the swelling and the bad odor. Treatment was done by surgical excision of the lesion.
CONCLUSIONS: EG has a variety of presentations and should be suspected when tenderness and local swelling are present. Radiography was found to be helpful in the diagnosis and surgical treatment was done to manage the case.

Intracranial epidermoid cyst is a rare pseudotumor of the nervous system, accounting for 0.2%-1.8% of all intracranial tumors. It is usually located in the cerebellopontine Angle or parasellar area, with insipid onset, slow growth and usually less than 2 cm in diameter. Giant epidermoid cysts that invade the bone have rarely been reported in the literature. Herein, we report a case of giant ECs extradural to the parietal bone, penetrating the skull and continuing to expand outward. In addition, a systematic search of four authoritative databases was conducted to collect the relevant reports of giant epidermoid cyst with diameter > 5cm for the first time, and to discuss the clinical and radiographic features of patients with giant epidermoid cyst and the influence of treatment options.

The authors provide a comprehensive framework with which to approach paediatric calvarial injury sustained as a result of suspected abusive head trauma (AHT). This is achieved through the presentation of a case series set in the context of the unique morphology of the infant skull and the possible diagnostic pitfalls which may arise due to the presence of variant anatomy or other mimicking conditions.
A retrospective analysis of sixty-three patients referred to our institution with suspected AHT was carried out. Seventeen patients with skull fractures were identified and their fractures were described in terms of anatomical location, type and course. Our data was then interpreted in the light of known anatomical fracture mimics and the available literature on the subject.
Forty-two skull fractures were identified and described in our cohort, most of which were simple linear fractures of the parietal bones (33%). There were also a substantial number of complex stellate fractures, namely of the parietal (29%) and occipital (10%) bones. Eleven fracture mimics including accessory sutures and wormian bones were also identified in this cohort.
Our study supports and builds on the existing literature, thereby offering a more complete view of the spectrum of calvarial damage sustained as a result of AHT in the context of its diagnostic pitfalls.

Osteoblastoma is a rare nonfibroblastic osteoid tissue-forming primary bony tumor usually arising in the medullary cavity/diploic space of any bone. The calvarium is an extremely rare site of its origin. Clinically, 2 types of osteoblastoma are noted: benign/conventional/typical and aggressive/high grade. Their imaging features are nondifferentiating and nonspecific, histopathologic features have a few subtle but nonspecific differences, and they have highly distinct clinical behavior. We report an extremely rare case of a patient with large aggressive cranial osteoblastoma, who developed massive inoperable multifocal recurrence 15 months after total en bloc resection with wide margins. A concise review of cases of aggressive osteoblastomas involving the cranium available in the English literature is also presented as an update.

BACKGROUND: Gorham-Stout disease (GSD) is a rare and idiopathic bone disorder, characterized by massive osteolysis. To date, there is no established treatment strategy for GSD. We empirically treated two patients, who had presented to us with cranial lesions of GSD. Here, we propose a novel algorithm for the management of Gorham\'s disease based on our experience and review the literature published to date.
METHODS: We reviewed all existing literature on GSD describing the pathophysiology and suggested treatment methods, up to 2018.
RESULTS: We found 13 papers with 14 reported cases; an inclusion of our two cases brings the total count up to just 16 recorded cases of GSD involving the skull. Of these, the base of the skull was affected in eight cases, while the remaining eight cases showed cranial involvement. The patients with skull-base involvement were managed conservatively, using medications or radiotherapy. The patients with cranial osteolysis were managed surgically, with an excision of the osteolytic portion, followed by cranioplasty. Of the latter group, the pericranium was not removed in one patient, in whom a very slight progression of the osteolytic process was later observed.
CONCLUSIONS: The pathogenesis of GSD remains poorly understood. Further study is required to determine an optimum management strategy. A long-term follow-up will also be necessary to establish the effectiveness of the treatment process. The untreated patients show a progressive resorption of the affected bones of the skull. A painful, vanishing skull deformity is an alarming sign of GSD. Early diagnosis and treatment are necessary to arrest disease progression and to prevent complications.

A 24-year old man was referred to the Erasmus MC Bone Center because of an asymptomatic increasing skull defect of the left parietal bone. The defect was first noticed at the age of six, and gradually increased over the years. His medical history was unremarkable, without any known trauma and a negative family history for bone diseases. Laboratory tests showed a low vitamin D level without other abnormalities. Particularly, there was no increase in markers of inflammation or bone turnover. CT-scans of the skull showed an osteolytic region of the parietal skull bone, with a two-centimeter increase in diameter over 9 years. Contrast enhanced MRI showed lymphangiogenic invasion, which was compatible with our suspicion of Gorham-Stout disease. The patient was referred to the neurosurgeon for treatment with a bone graft while considering additional drug treatment. Gorham-Stout or vanishing bone disease is a rare entity characterized by progressive osteolysis with lymphangiogenic bone invasion. Although already reported in 1838, currently the diagnosis and treatment of Gorham-Stout disease is still challenging. The underlying pathophysiology is not clarified yet and several theories exist. The disease usually affects persons younger than 40 years and the majority present with bone disease of the maxillofacial region, the upper extremities or the torso. The clinical presentation includes most frequently pain, swelling, and functional impairment of the affected region, but the disease can also be asymptomatic. Laboratory investigations are usually normal, and diagnosis is based upon imaging and sometimes pathology examination of affected bone tissue. Treatment is experimental and there is no general consensus about the best option due to lack of randomized controlled trials. Case reports showed patients treated with bisphosphonates, interferon-alpha, anti-VEGF therapy, mTOR inhibitors, and radiotherapy. There are some reports of surgery with prosthetic or bone grafts but no long-term follow-up data exist. This paper describes a unique case of Gorham-Stout disease of the parietal skull bone and discusses the current state of knowledge about this rare bone disease.

Primary intradiploic epidermoid cyst of the central nervous system (CNS) is a rare disease. More than 200 cases have been reported so far. The lesion can affect every flat bone of the cranium. The pre-operative diagnosis is always misleading. We reported a 61-year-old female with giant primary intradiploic epidermoid cyst in the parietal bone. Surgical resection was performed. The patient recovered well with no complication nor neurologic dysfunction. A literature review of the disease will also be presented here.
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BACKGROUND: Penetrating brain injury (PBI) caused by a nail gun is an extremely rare neurosurgical emergency that poses a challenge for neurosurgeons because of its rarity and complexity.
METHODS: Here we present 3 cases of PBI caused by a nail gun. In the first case, the nail entered through the right parietal bone and lodged in the right parietal lobe and basal ganglia. In the second case, the nail entered through the right occipital bone and lodged in the right occipital lobe. In the third case, the nail entered through the right parietal bone and lodged in the right frontal and parietal lobes. All patients underwent surgical removal of the nail. The first patient presented with reduced left-side strength, whereas the second and third patients were neurologically intact on presentation.
CONCLUSIONS: PBI caused by a nail gun can present with differing clinical manifestations, and most cases require immediate surgery. A rational management strategy should provide a good postoperative prognosis with minimal neurologic deficits in these patients.