CNS lymphoma

CT brain shows two hyperdense nodular deep white matter lesions located in the right corona radiata region and in the left frontoparietal transition, both associated with an extensive hypoattenuating area surrounding them and that may correspond to a vasogenic edema. The mass effect is more pronounced in the right where it causes a mild right lateral ventricle compression; bilateral mild sulcal effacement. No midline shift. It is also notated a small not well-defined hypoattenuating area in the left cerebral peduncle. 

MRI brain demonstrating again the right frontal lobe and left frontoparietal white matter nodular lesions associated with a extensive vasogenic edema. Both lesions show homogeneous and intense contrast enhancement and the left one a mild hemorrhagic posterior component. The study also evidences a similar enhanced nodular lesion in the left cerebral peduncle. 

MICROSCOPIC DESCRIPTION: 1&2: Paraffin sections show fragments of brain parenchyma which are densely infiltrated by a population of atypical large lymphoid cells mixed with smaller mature lymphocytes. The large cells have convoluted vesicular nuclei, many with conspicuous nucleoli and a varying amount of pale cytoplasm. Both populations are arranged in diffuse sheets as well as cuffs around blood vessels. The walls of some vessels are obliterated by the infiltrate. Immunohistochemistry shows positive staining in tumor cells for CD20 and CD5. Scattered atypical cells show positive staining for MUM-1. Atypical cells are negative for CD3, CD10, CD23, cyclin D1, CD30, bcl-2, bcl-6 and EBV-LMP. Moderate numbers of small mature CD3+ T lymphocytes are mixed with the large atypical B cells. The features are of non-Hodgkin's large B cell lymphoma. DIAGNOSIS: "Right frontal brain lesion": non-Hodgkin's diffuse large B cell lymphoma.