Micrograph showing a<unk>  with the characteristic perivascular distribution composed of large cells with prominent nucleoli. Brain biopsy. HPS stain. The current standard for diagnosis typically includes positive CSF cytology, vitreous biopsy, or brain/leptomeningeal biopsy. Histopathological confirmation is essential for definitive diagnosis. MRI or contrast enhanced CT classically shows multiple ring-enhancing lesions in the deep white matter. The major differential diagnosis (based on imaging) is cerebral toxoplasmosis, which is also prevalent in AIDS patients and also presents with a ring-enhanced lesion, although toxoplasmosis generally presents with more lesions and the contrast enhancement is typically more pronounced. Imaging techniques cannot distinguish the two conditions with certainty, and cannot exclude other diagnoses. Thus, patients undergo a brain biopsy or vitreous biopsy, if there is intraocular involvement. Classification Most<unk> s are diffuse large B cell non-Hodgkin<unk> s.
Primary central nervous system lymphoma
Malignant multiple sclerosis
Lymphocytic meningoradiculitis
Leptomeningeal cancer
Brainstem glioma
Brain metastasis
Central nervous system cavernous hemangioma
Autoimmune encephalitis