<prompt> True about primary CNS lymphoma -a Reticulin staining is doneb Essentially B cell typec Have an association with EBVd Indolent disease with good prognosise Chemotherapy is highly effectiveababcacdbcd  <response>: Primary CNS lymphoma It is most common CNS neoplasm in immunosuppressed patients accounts for 1 of intracranial tumors.Affects all ages. Its peak incidence is in sixth seventh decades in immunocompetent but younger in immunosuppressed patients.More than 98 of PCNSL are B-cell lymphomasOften have multiple sites of tumor within brain parenchyma c.f. NHL arising outside rarely involves brain parenchymaMost common locations are the frontal lobes, followed by deep nuclei and periventricular zone.Reticulin stains demonstrate that the infiltrating cells are separated from one another by silver-staining material; this pattern is characteristic of primary brain lymphoma and is referred to as hooping.In immunocompromised patients, PCNS lymphoma are invariably associated with EBV infection of tumor cellsThe main stay of definitive therapy is chemotherapy by methotrexate, vincristine, procarbazine, cytarbine etc. Therapy also includes glucocorticoids and rituximab.A unique features of PCNSL in comparison to other brain tumors is its exquisite sensitivity to corticosteroids.Surgery is important to confirm the histological diagnosis but has no therapeutic roleIs an aggressive disease with relatively poor response to chemotherapy compared to peripheral lymphomaSurvival with AIDS-related PCNSL is very poor, generally 3 months; the degree of immunosuppression and the extent of CNS dissemination at diagnosis all appear to influence outcome. 