The topic of the tumor board this week regards central nervous system (CNS) rhabdoid tumors (RHTs). We chose this topic, first of all, to try to elaborate a rational therapeutic plan for the patient who will be presented and, second, to highlight the unique biological phenomena that appear to link RHTs with CNS tumors. The existence of extrarenal RHTs as an entity has recently been questioned by Weeks et al. [ 13, who argued that many neoplasms can mimic the light microscopic appearance of RHT of the kidney (RHTK). They suggest that RHTs represent merely a phenotype and not an entity and that extrarenal RHTs will eventually "emerge as a phenotypic concept encompassing a spectrum of histogenetic and clinical diversity." It is important to recall these statements before opening the discussion and to take a more critical view of the biological and clinical problems of RHTs.
So much for introduction; we can now proceed with the presentation of the case.
The patient is a 5-year, 1 1-month-old white girl who was well until early April 1990, when she developed headache and photophobia. Two to 3 days before admission, the patient developed worsening headache, vomiting, and right disconjugate gaze. Her neurological examination on admission revealed bilateral papilledema, right homonymous hemianopsia, decreased visual acuity and mild bilateral sixth nerve palsy. A brain tumor was suspected, and a magnetic resonance image (MRI) of the brain was requested. Dr. Gusnard, will you please discuss the findings?