Paraneoplastic brainstem encephalitis

Light micrograph from a section of brainstem from a patient with colon cancer and paraneoplastic brainstem encephalitis associated with anti-Ma2 antibodies. There is a perivascular lymphocytic infiltrate on the right side (large arrow), while the middle shows several reactive astrocytes (gliosis) and a neuron undergoing degeneration (small arrow). Parenchymal infiltrates of mononuclears cells are more apparent on the left side of the picture.