Background: Rosai-Dorfman disease (RDD) is a rare type of histiocytosis that can manifest with diverse symptoms. It usually presents with systemic involvement, and only a few cases have been reported at the level of the skull base. RDD typically follows a benign course during the progression of the disease. In this particular case reported, after the skull base invasion, the disease started to infiltrate the brain parenchyma. Our objective for this case report was to present this particular progression pattern and the nuances of its surgical treatment. In addition, a revision of the current literature was performed about skull base RDD with intracranial invasion and brain parenchyma infiltration not previously described. Case Description: We are presenting the case study of a 57-year-old male patient who was experiencing severe headaches and an increase in volume in the right fronto-orbital region. On clinical examination, no neurologic clinical symptoms were observed. Contrast computed tomography and magnetic resonance imaging showed a tumor mass that affected the right orbit, frontal paranasal sinus, greater sphenoid wing, and right frontal lobe with moderate adjacent brain edema. The patient underwent surgery using an extended pterional approach with intracranial, orbital decompression, and frontal sinus cranialization, accompanied by frontal lobe tumor resection. Neuropathologic diagnosis revealed a Rosai-Dorfman histiocytosis disease. Conclusion: The etiopathogenesis of RDD is still not completely understood. The current literature considers this disease to have a predominantly benign course. Nevertheless, as we have shown in this case, it may, in some cases, present direct parenchymal invasion. We consider that prompt surgical treatment should be ideal to avoid the local and systemic progression of the disease.

Background: Collision sellar tumors are rare disease entities. Less than 30 cases have been reported in the literature in the last 20 years. We present the case of one patient diagnosed with a collision sellar tumor and describe the use of Enhanced Contact Endoscopy for pituitary gland and tumoral identification not previously described in the literature. Case Description: The patient is a 57-year-old man who presented with visual field deficits and intense frontal headache accompanied by a slight hypothyroidism. Magnetic resonance imaging shows two different lesions in the sellar area, with a pendular effect of the pituitary stalk displaced to the side of the pituitary adenoma. The patient was operated on with an endoscopic endonasal subsellar approach, aiding with an enhanced contact endoscopy to demarcate the pituitary gland from the tumor adequately. Pathology diagnosis was compatible with pituitary adenoma (First lesion) and papillary craniopharyngioma (Second lesion). A short surgical video was added to complement the learning of the technique for enhanced contact endoscopy for a description of the microvasculature pattern. Conclusion: Collision sellar tumors are a rare pathology in the sellar region and could benefit from a variety of combined treatments for optimal outcomes. Enhanced contact endoscopy for pituitary surgery could be useful for distinguishing the normal pituitary gland from the tumor.

Background: Endoscopic endonasal corridor is valuable for accessing and treating midline skull base pathologies. In the present work, we will discuss the anatomy of the medial wall of the orbit from an endonasal endoscopic perspective. Methods: Six human cadaveric specimens underwent endonasal endoscopic dissection at the Surgical Neuroanatomy Laboratory of the Mexican Faculty of Medicine of La Salle University. We used a 0°, 4 mm diameter, and 18 cm length rigid endoscope using a 4K high-definition neuro-endoscopic visualization system, specialized surgical instruments for endonasal endoscopic surgery, and a high-speed drilling system. Results: In the endonasal endoscopic to the medial wall of the orbit, we describe two approaches: the superomedial approach (SMA) and the inferomedial approach (IMA). The SMA is located between the lower border of the superior oblique muscle and the superior border of the medial rectus muscle (MRM), and the IMA is located between the inferior border of the MRM and the superior border of the inferior rectus muscle. The topographic anatomy of the contents of each approach is described. Conclusion: The endoscopic endonasal corridor safely reaches the medial half of the orbit through the inferomedial and SMAs.

Background: The internal carotid artery (ICA) has multiple classification systems; it is essential for brain blood supply, which has bone/neurovascular relationships of wide neurosurgical interest; its anatomy must be known in detail, its angiographic-imaging aspect (endovascular), its ventral aspect (endoscopic endonasal approaches); and its lateral aspect (anterolateral skull base surgery). Our objectives were to identify coincidences/differences between the main classifications of the ICA to improve its surgical-anatomical understanding, unify the terminology of ICA segments, avoid confusion, and carry out a simple description. Methods: There are differences between classifications; however, these may overlap each other and determine the correspondence between segments, regardless of their purpose. Literature on ICA classifications was reviewed; a cadaver endonasal endoscopic and anterolateral skull base dissection was performed, obtaining representative images of the ICA, as well as angiography. The main terminology of ICA segments was collected, and artistic-anatomical illustrations were created to facilitate the study of ICA. Results: We compared the endoscopic roadmap to the ICA by Labib/Kassam, the extradural ICA at its lateral aspect by Cherian, and the classic classification by Bouthillier (as well as a small reference to the classification by Gibo/Rhoton). We found the shared characteristics and differences between classifications, with a total of 17 interrelated segments, with a variety of nomenclature and anatomical extension. Initially, we except the extradural ICA by Cherian because it uses almost the same nomenclature that Labib, varying in one segment, which coincides with the nomenclature of Bouthillier and does not change the total summary. The initial and terminal segments were nominative/anatomically equivalent, and there is anatomical nominal variation in the intermediate segments and its relation/correspondence has been easily demonstrated. Conclusion: Anatomical knowledge of all aspects of ICA using its main classifications, the relation between them, and its diversity of nomenclature is essential to improve its anatomical-surgical understanding and avoid anatomical nominal confusion. It can be achieved through our comparative tables/illustrations.

Resumen El síndrome del foramen magno es la presentación clínica más frecuente de una diversidad de etiologías que tienen su origen en los márgenes de dicha estructura anatómica. Sus manifestaciones clínicas incluyen una gama diversa de signos y síntomas, muchas de ellas explicadas por la correlación anatómica con las estructuras afectadas. Su estudio es un reflejo claro de la importancia de la neuroanatomía en la aplicación clínica. La mayor parte de las etiologías tumorales de esta zona son de índole benigna, por ende, potencialmente resecables, de allí la importancia de su reconocimiento y diferenciación con otras entidades autoinmunes, congénitas, etcétera. Si no son reconocidos a tiempo, pueden ser mortales a causa de una compresión alta de la porción superior de la médula cervical y/o médula oblongada. Aunque estos tumores son infrecuentes (aproximadamente 1% de todos los tumores espinales e intracraneales), los más comunes son los meningiomas, schwannomas, neurofibromas y los quistes dermoides. La mejor manera de no pasar por alto este tipo de cuadros es el tener en mente la definición y los elementos constitutivos del "síndrome del foramen magno", lo cual facilitará la recolección y comprensión de los datos clínicos encontrados en el paciente.