PRIMARY KI-1 (ANAPLASTIC LARGE-CELL) LYMPHOMA OF THE BRAIN AND SPINAL-CORD

The authors report a case of primary Ki-1 lymphoma of the brain. The p atient was a 4 1/2-year-old black girl who presented with a 4- to 5-da y history of headaches, nausea, vomiting, neck stiffness, and difficul ty in walking. Computed tomography (CT) scan of the brain showed two d iscrete densities in the left occipital lobe and in the brain stem. Ma gnetic resonance imaging (MRI) showed multiple densities scattered ove r the brain surface and brain stem. Microscopically, the tumor was an anaplastic neoplasm that diffusely infiltrated brain parenchyma. The n eoplastic cells were large with amphophilic cytoplasm, large nuclei wi th irregular nuclear contours and prominent nucleoli. A high mitotic r ate including atypical mitotic figures was noted. Immunohistochemical stains showed diffuse strong positivity for CD30 and moderate focal st aining for epithelial membrane antigen. Leukocyte common antigen, cyto keratin, neuron specific enolase, monocyte/macrophage and B- and T-mar ker stains were negative. The histology was characteristic for Ki-1 la rge cell lymphoma. Cytologic examination of cerebrospinal fluid (CSF) demonstrated similar neoplastic cells. This is one of the first report s of this variant in the pediatric population.