{"id":"939711d3-820e-4385-8cb0-1923aa1e6f0f","slug":"fulminant-presentation-of-a-smarcb1-deficient-anterior-cranial-fossa-tumor-in-adult","title":"Fulminant presentation of a SMARCB1-deficient, anterior cranial fossa tumor in adult","authors":["Idan Levitan","Suzana Fichman","Yosef Laviv"],"abstract":"Background: Malignant atypical teratoid rhabdoid tumor (ATRT) usually develops in children. ATRTs are rare in adults, with only one case in the literature describing involvement of the anterior skull base. These primary intracranial tumors are characterized molecularly as SMARCB1 (INI1) deficient. Different types of such SMARCB1-deficient tumors exist in adulthood, usually in the form of extracranial tumors. Very few cases of such a new entity, named SMARCB1-deficient sinonasal carcinoma have been described with intracranial penetration and involvement of the anterior cranial fossa. Case Description: A 36-year-old male presented with acute cognitive deterioration. Over few hours, he developed a fulminant herniation syndrome. Imaging showed a tumor in the anterior cranial fossa surrounded by massive brain edema. The tumor has destroyed the frontal bone with involvement of the nasal cavities and paranasal sinuses. The patient underwent emergent decompressive craniectomy and tumor debulking but could not be saved. Pathological analysis revealed a highly cellular tumor without rhabdoid cells but with areas of necrosis. Further immunohistochemical stains revealed that neoplastic cells were diffusely and strongly positive for epithelial membrane antigen and P63 and negative for SMARCB1 (i.e., loss of expression), confirming the diagnosis of sinonasal carcinoma. Conclusion: To the best of our knowledge, this is the first report of a fulminant presentation of a SMARCB1- deficient tumor in young adult, involving the anterior cranial fossa and the paranasal sinuses. The main differential diagnosis of aggressive, primary, intracranial SMARCB1-deficient tumors in adults includes ATRT, SMARCB1- deficient sinonasal carcinoma, rhabdoid meningioma, and rhabdoid glioblastoma. Atypical tumors involving the anterior skull base without a clear histopathological pattern should therefore be checked for SMARCB1 expression. A number of tumor suppressor genes are important in regulating transcription in eukaryotic neoplastic tissue. SMARCB1 is such a gene which has been named by acronyms for its function: switch/sucrose nonfermentable (SWI/SNF) related, matrix-associated, actin-dependent regulator of chromatin, subfamily B, member 1. It is a tumor suppressor gene that encodes a core subunit of the SWI/SNF chromatin-remodeling complex positively regulating transcription of a particular set of genes involved in differentiation, tumorigenesis, invasion, and apoptosis.[ 22 , 33 ] The gene is located at chromosome 22q11.23 and is also known as HIV integrase interactor1 or INI 1. SMARCB1 is ubiquitously expressed in the nuclei of all nonneoplastic cells and can be readily identified using immunohistochemistry.[ 15 ] Biallelic inactivation of SMARCB1 was originally described in atypical teratoid rhabdoid tumors (ATRTs).[ 29 ] However, this gene is not limited to ATRT and can be found in a variety of other tumors, including extracranial soft-tissue tumors (e.g., extrarenal malignant rhabdoid tumor, epithelioid sarcoma, some extraskeletal myxoid chondrosarcomas, some epithelioid malignant peripheral intracranial nerve sheath tumors, and some myoepithelial tumors) as well as few cranial tumors.[ 15 ] The spectrum of non-ATRT, cranial SMARCB1-deficient tumors mostly includes other pediatric tumors, such as the benign cribriform neuroepithelial tumor and rare poorly differentiated chordomas.[ 9 ] In adults, they also include the recently described SMARCB1-deficient sinonasal carcinoma[ 3 ] and other meningeal SWI/SNF-related, SMARCB1-deficient tumors.[ 11 ] The rarity of these pathologies in adults poses significant diagnostic difficulties, which require meticulous clinical, radiological, and above all, pathological evaluation to arrive at the correct diagnosis. We present an extremely rare case in which a SMARCB1- deficient tumor, with both extracranial and intracranial components, presented with a fulminant clinical course of cognitive deterioration and subsequent loss of consciousness, resulting in death in a young adult. The differential diagnosis of primary, cranial, and SMARCB1-deficient tumors in adults is discussed.","thumbnailUrl":"https://sni-digital-videos.s3.amazonaws.com/articles/939711d3-820e-4385-8cb0-1923aa1e6f0f/featured/hero-1781563315164.png","publishDate":"2020-07-18T00:00:00.000Z","doi":"10.25259/SNI_171_2020","categories":["Neuro-oncology","Case Report"],"fullTextUrl":"https://surgicalneurologyint.com/wp-content/uploads/2020/07/10139/SNI-11-195.pdf"}