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Washington University Experience | NEOPLASMS (NON-GLIAL NON-NEURONAL) | Choroid plexus papilloma | 11D Case 11 Comment
Comment ---- This is an old case (1997) in which the interpretation was “choroid plexus papilloma with anaplasia”. At that time we thought that the nuclear atypia and pleomorphism were not as prominent as would be expected in a choroid plexus carcinoma and that this neoplasm had the general architectural and cytologic features of a choroid plexus papilloma, however, the striking prominence of mitotic activity and the presence of extensive necrosis were worrisome features in terms of biological behavior. A battery of immunohistochemical stains were performed. The tumor cells showed positive reactivity for S-100, CK) and negative reactivity for CEA, EMA, and GFAP. We were influenced by a study of choroid plexus neoplasms (Coffin et al., Am J Surg Pathol 10:394, 1986) in which CEA positivity coupled with S-100 immunonegativity was associated with malignant behavior and, as in our current case, S-100 reactivity without CEA immunoreactivity was considered a benign feature. The patient was lost to follow up following surgery. ---- Using modern histopathologic features outlined in the WHO 2021 manual this tumor would likely be considered a choroid plexus carcinoma. The use of molecular techniques has helped resolve borderline cases. Methylome analysis has revealed three clinically distinct subgroups of choroid plexus tumors, with all choroid plexus carcinomas clustering within the same subgroup, together with prognostically unfavorable grade 1 and 2 choroid plexus tumors [Thomas et al. (2016) Neuro Oncol 18:790-6].
