The dura of the orbital roof is vascularized by the lateral branches of the anterior meningeal arteries and variably by branches of the middle meningeal artery. The frontal division of the middle meningeal artery usually gives rise to some branches for the far lateral dura of the orbital roof and a large branch that runs towards the superior orbital fissure. This branch can reach the ophthalmic artery (meningo-ophthalmic artery) or the lacrimal artery (meningo-lacrimal artery), passing through either the superior orbital fissure or an isolate lateral foramen (Hyrtl’s foramen), reported in <20% of cases (Fig. 1). After entering the orbit, the meningo-ophthalmic or meningo-lacrimal artery gives rise to a small branch that recurs through the superior orbital fissure or Hyrtl’s foramen to provide the blood supply of the dura of the lesser wing of the sphenoid bone. Furthermore, additional meningo-orbital foramina can be found along the lateral portion of the orbital roof, serving as routes for branches of the lacrimal artery for the blood supply of the dura of the anterior cranial fossa. Rarely, the paraclinoid internal carotid artery gives rise to some small branches that perforate the anterior clinoid process and vascularize the surrounding dura [1].
Acknowledgements
Figures 1, 4, 5, 8, and 9 were prepared at the Laboratory of Endoscopic Anatomy of the University of Brescia, in collaboration with Prof. Luigi Fabrizio Rodella and Dr. Barbara Buffoli. Figures 2, 3, 6, and 10–13 were prepared at the Medical University of Vienna, in collaboration with Prof. Manfred Tschabitscher, Dr. Lena Hirtler, Dr. Francesco Doglietto, and Dr. Francesco Belotti.
Disclosure Statement
The authors have no conflicts of interests concerning the present work.
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Marco Ferrari, MD
Unit of Otorhinolaryngology – Head and Neck Surgery, Department of Medical and Surgical Specialties
Radiological Sciences and Public Health, University of Brescia
Piazzale Spedali Civili 1, IT–25123 Brescia (Italy)
E-Mail [email protected]
Nicolai P, Bradley PJ (eds): Anterior Skull Base Tumors. Adv Otorhinolaryngol. Basel, Karger, 2020, vol 84, pp 13–27 (DOI: 10.1159/000457922)
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Pathology and Differential Diagnosis of Anterior Skull Base Tumours
Michelle D. Williams Adel K. El-Naggar
Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Abstract
The anterior skull base is a complex anatomic site which may be involved by a large number of biologically heterogenous neoplasms. They arise from the epithelium, both surface mucosa and glands, as well as soft tissues, bone, and cartilage. Many benign and malignant tumours in the anterior skull base are similar to their counterparts in other anatomic sites. Interestingly, unique tumours including teratocarcinosarcoma, olfactory neuroblastoma, and angiofibroma can also be found. Recognition of overlapping morphologic features of entities encountered in this anatomic site and the corresponding differential diagnosis is critical. The integration of both morphologic features and immunohistochemical evaluation is essential for correct diagnostic interpretation. This is particularly notable in small round blue cell tumours for which morphologic lineage differentiation is lacking, thus requiring immunohistochemical characterisation. Moreover, challenges in accessing tissue for diagnosis leads to limited biopsies that require proper handling for adequate assessment. Histologic evaluation combined with communication between surgeons and pathologists are necessary components in the work-up and evaluation of these rare tumours.
© 2020 S. Karger AG, Basel
The skull base region comprises diverse structures and tissue lineages that give rise to phenotypically and biologically heterogeneous neoplasms. Histologic classification of tumours arising at these sites may lead to diagnostic challenges especially on presurgical materials [1]. In general, diagnosis of skull base tumours is made by tissue biopsy in the office, operating room, or, in selected cases, by core biopsy under CT guidance. In view of the risk of misdiagnosis, intraoperative diagnosis based on frozen sections should be limited to deep-located lesions, which are difficult to access under local anaesthesia, after an in-depth discussion between the surgeon and pathologist. Tissue biopsies provide limited materials and efforts to ensure proper handling and processing are critical. Accurate