 Hi everyone, I am Dr. Prithviraj Desai from Goa Medical College. Today, I am presenting a case report on primary CNS lymphoma. Primary CNS lymphoma originates in the brain, left of meninges, spinal cord, or eyes and typically remains confined to the CNS, with only rare spread outside the nervous system. There is no co-existing systemic disease at the time of diagnosis, distinguishing it from CNS enrollment from systemic lymphoma, that is secondary CNS lymphoma. It is a rare tumor accounting for 2-6% of all primary brain tumors and 1-2% of all non-Hoskine lymphomas. Primary CNS lymphoma in the vast majority of patients is a subtype of non-Hoskine lymphoma and is usually large cell or immunoblastic type and is by definition restricted to the CNS. It is encountered in the immunocompetent and in the immunocompromised patients, but the cause and behaviour of the primary CNS lymphoma differ based on the affected population. Immunocompromised patients are at particular risk for developing primary CNS lymphoma which is typically secondary to HIV, organ transplantation, or congenital immunodeficiency syndromes. Our patient is a 79-year-old female who presented to the emergency room with chronic headache with progressive arsenic. The patient had progressive confusion and unusual behaviour. There was associated weakness of left upper and lower limbs. There was no history of immune dysfunction. On examination, the vitals including body temperature, blood pressure and heart rate was within normal limit. On neurological examination, the power in left upper and lower limbs was co-by-five. City brain was performed in the emergency department which revealed abnormal findings. Further evaluation with MRI revealed altered areas of white matter signal density involving right frontal parietal region including the paramedicular region extending across the anterior body of corpus callosum minimally into the left frontal region, right external capsule, internal capsule insula and right cerebral peduncle. DWI shows diffusion restriction in the involved areas with areas of low signal on ADC. On post-contrast images, the legion shows patching inhomogeneous enhancement. MR spectroscopy reveals choline peak with increased choline to NNA and choline to creatine ratio. Based on MRI findings, a possible diagnosis of CNS lymphoma was made. Subsequently performed stereotactic biopsy revealed it to be a diffused large B cell lymphoma. Discussion Primary CNS lymphoma is one of the most aggressive of the diffused large B cell lymphomas. Primary CNS lymphomas represent around 20% of all cases of lymphomas in HIV-PID infections. It is confined to CNS including the brain, spine, CSF and eyes. Primary CNS lymphoma is highly associated with Epstein-Barr virus infection in immunodeficient patients. In immunocompromised patients prognosis is usually poor. In immunocompetent patients, there is rarely an association with Epstein-Barr virus infection or other DNA viruses. In the immunocompetent population, it appears in older patients in their 50s and 60s. Clinical Features Patient with primary CNS lymphoma developed neurological science over weeks which include focal neurological deficit, mental status and behavioral changes and symptoms of increased intracranial pressure. It is usually seen in patients over 50 years of age. There is a strong association with the HIV and other immunocompromised states. In pathology, majority are B cell in origin, many Indian CNS usually accumulate around and within the blood vessels. Imaging They are usually present as solitary or multiple legions with predilection towards the perimetrical or white matter. They can also arise from the cortex or deep grey matter. They are often seen crossing the corpus callus. Mostly they are located in supra-tendoral neuroparenchyma. City Findings Immigrant lymphomas are hyperdense on non-contrast CT with associated minimal perillegional edema. On contrast study, it shows avid enhancement. HIV patients often show multiple legions with heterogeneous enhancement and central non-announcing necrotic areas. Hemorrhage is uncommon. MRI Findings On T1, it appears hypointense to grey matter. T2 shows variable signal intensity. When hypointense, it is a useful differentiating feature. On post-contrast scans, high-grade legions show intense homogenous enhancement. Low-grade legions show absent or moderate enhancement. Peripheral enhancement is seen in immunocompromised patients. Nausein, suggestive of infiltrative or irregular growth pattern. On DWI, it shows restriction. MR spectroscopy, large colon peak with markedly decreased NAA. MR perfusion, only modest increase in cerebral blood volume. Thelium skin digraphy and FTG pack shows increased uptake. Management, unlike other brain tumors, it often has a favorable response to both chemotherapy and radiation therapy. But compared with lymphomas, outside the CNS, survival is usually inferior. The prognosis for primary CNS lymphoma that has failed first-line therapy remains poor. Although new therapeutic approaches have improved survival, the management of this disease still poses a challenge in neuro-oncology. Differential diagnosis Secondary CNS lymphoma, it is indistinguishable on imaging, however shows increased involvement of lefto-manages, cerebral toxoplasmosis, glioblastoma-multiformin, central necrotic areas and hemorrhage is common. Others include tumor-affective MS, ADEM, cerebral abscess, and neurosurcharosis. These are my references. Thank you everyone for your patient listening.