Fetal ependymoma associated with Down's syndrome

Down's syndrome (DS) is the most common multiple malformation syndrome occurring in humans and is associated with an increased risk of childhood malignancies, in particular leukemias. However, solid tumors seem to be underrepresented in DS patients and brain tumors occurring in association with DS have so far been limited to sporadic case reports, predominantly in children and young adults. We present the first case of an ependymoma associated with DS. This is also the youngest patient with DS suffering from a brain tumor as well as the first case in the English literature of a fetal ependymoma. The tumor was discovered incidentally at autopsy in a female fetus with DS after amniocentesis and termination of pregnancy in the 19th gestational week. Neuropathological examination revealed a tumor of 3x2x1 mm attached to the medulla oblongata rostrally of the floor of the fourth ventricle. Histologically, the ependymoma was moderately cellular and well demarcated with numerous perivascular pseudorosettes. Immunohistochemistry showed strong reactivity for GFAP, in particular of the fibrillary elements of the pseudorosettes, while the neuronal marker synaptophysin was not expressed. The Ki67/MIB-1 proliferation index was 0.5%.