A 57yearold man with a history of chemotherapy because of cutaneous lymphoma presented with an orbital apex syndrome. The cranial computed tomography scan revealed a tumour in the orbital apex, extending intradurally. With a suspected diagnosis of a neoplastic lesion, the patient underwent orbital surgery with optic nerve decompression. Histology revealed an aspergilloma. No other foci were seen and treatment with antifungals was started. In immunocompromised patients with intracranial tumours, infection is always a major consideration in the differential diagnosis, even if the reason for immunosuppression (in this case chemotherapy) dates back several months. Misdiagnosing an orbital apex lesion as a cancer and treating patients primarily with corticosteroids can be life threatening. Removal or biopsy of such lesions is essential in further treatment since antifungals have to be administered as fast as possible.

Chondromas usually affect the small bones of hand and feet and account for only 0.5% of all intracranial tumors. We present a case of a giant, supratentorial meningeal chondroma in a 19-year old male patient and discuss the preoperative diagnostic findings as well as the appropriate treatment options. A 19-old male presented with headache, new onset of focal seizures and paresis of left upper extremity. Magnetic resonance imaging revealed a large right parietal tumor in the precentral region with local mass effect. The patient underwent right parietal craniotomy and gross total resection of the tumor. The histopathological report revealed a chondroma. Intradural supratentorial chondromas are extremely rare. As with other slow growing intracranial masses, they often reach a relatively large size before generating symptoms. Maximal surgical resection is the treatment of choice and if this is achieved no adjuvant therapy is necessary.

There are a number of different surgical approaches in middle cerebral artery (MCA) aneurysm surgery. Evolution from the classical pterional approach towards smaller modified approaches took place over the years. In the present report, we describe a new modified approach in the treatment of MCA aneurysms, which is almost exclusively subfrontal. A modified approach was used on three patients with MCA bifurcation aneurysms. Craniotomy was subfrontal and suprapterional with minimal dissection of the temporal muscle and no drilling of the pterion. In all three cases, after establishing proximal control and dissecting the M1 carefully, retraction of the frontal lobe elevated the sylvian fissure and allowed opening of the fissure. The aneurysm could be identified easily and clips were applied. There was no infection and complete aneurysm clipping was achieved in all 3 patients. The described minimal craniotomy to the MCA through a subfrontal-suprapterional approach allows dissection of peripheral MCA bifurcation aneurysms without any problems.

Pilocytic astrocytomas correspond to low-grade gliomas and therefore metastasize exceedingly rare. However, pilocytic astrocytomas are able to and leptomeningeal dissemination may be seen. What are the treatment options of these cases? We present a case report of a 3-year-old child with a pilocytic astrocytoma of the optic chiasm with leptomeningeal dissemination of the spinal meninges. Partial resection of the cerebral tumor has been performed. Since the leptomeningeal dissemination was seen all over the spinal meninges, the child did not undergo further surgical treatment. A wait and watch strategy were followed. Chemotherapy was initiated, if a 25% tumor growth was seen. Leptomeningeal dissemination of a pilocytic astrocytoma is seen so infrequently that no standard therapy is established. Since these metastases may occur even up to 2 decades after primary tumor resection, long-term follow-up is indicated. In case of spinal metastases, surgical treatment should be performed if feasible. Otherwise observation should be possessed and/or chemotherapy should be initiated.

BACKGROUND Brain metastases from the gastrointestinal tract are a rare event (less than 10% of all brain lesions), but their impact on prognosis is remarkable. Their incidence is increasing due to earlier diagnosis and prolonged survival because of more effective treatment modalities. Because of the lack of evidence-based recommendations, no optimal treatment strategy has been defined. Hope might come from the discovery of new prognostic and predictive factors and their biological inhibitors. The aim of this study was to create a repository of matched primary cancer and brain metastases samples for clinicopathologic and molecular correlations of gastrointestinal tumors and to analyze changes in expression signatures between both samples. The main goal was to study the metastatic process and characterize the immune response by characterizing features such as invasiveness, vascular co-option, proliferation, stemness and cell-type heterogeneity between the matched tissues. METHODS We searched for patients at Stanford hospital with matched brain metastases from gastrointestinal tumors from 2008 to 2020 using the STARR database (The STAnford Research Repository, or STARR, is Stanford Medicine's approved resource for working with clinical data for research purposes.). Matched specimens mean that both brain metastases and gastrointestinal tumors were studied at Stanford University. FFPE blocks from these matched patients were sectioned and sections analyzed for gene expression analysis using nanoString nCounter technology and the immune-oncology panel. RESULTS Expression data from 32 matched patients with primary tumor and brain metastases will be discussed at the meeting. CONCLUSION We believe that analysis of changes in expression signatures between the matched primary gastrointestinal cancer and brain metastases will provide novel insights into the role for tumor factors, such as invasiveness, proliferation and stemness, and the tumor microenvironment in progression.