Expression of Oligodendrocyte Precursor Cell Markers in Canine Oligodendrogliomas.

Oligodendroglioma is a common brain tumor in dogs, particularly brachycephalic breeds. Oligodendrocyte precursor cells (OPCs) are suspected to be a possible origin of oligodendroglioma, although it has not been well elucidated. In the present study, 27 cases of canine brain oligodendrogliomas were histologically and immunohistochemically examined. The most commonly affected breed was the French Bulldog ( n = 19 of 27, 70%). Seizure was the most predominant clinical sign ( n = 17 of 25, 68%). The tumors were located mainly in the cerebrum, particularly in the frontal lobe ( n = 10 of 27, 37%). All cases were diagnosed as anaplastic oligodendroglioma (AO) and had common histologic features characterized by the proliferation of round to polygonal cells with pronounced atypia and conspicuous mitotic activity (average, 10.7 mitoses per 10 high-power fields). Honeycomb pattern ( n = 5 of 27, 19%), myxoid matrix ( n = 10, 37%), cyst formation ( n = 6, 22%), necrosis ( n = 19, 70%), pseudopalisading ( n = 5, 18.5%), glomeruloid vessels ( n = 16, 59%), and microcalcification ( n = 5, 19%) were other histopathologic features of the present tumors. Immunohistochemically, the tumor cells were positive for Olig2 in all cases and for other markers of OPCs in most cases, including SOX10 ( n = 24 of 27, 89%), platelet-derived growth factor receptor α ( n = 24, 89%), and NG2 ( n = 23, 85%). The present AO also consisted of heterogeneous cell populations that were positive for nestin ( n = 13 of 27, 48%), glial fibrillary acidic protein ( n = 5, 19%), doublecortin ( n = 22, 82%), and ßIII-tubulin ( n = 15, 56%). Moreover, cultured AO cells obtained from 1 case retained expression of OPC markers and exhibited multipotent characteristics in a serum culture condition. Overall, the findings suggest that transformed multipotent OPCs may be a potential origin of canine AO.

Sarcocystis calchasi encephalitis in a rock pigeon.

A rock pigeon (Columba livia) caught in Akihabara, Tokyo, showed neurological symptoms, such as head tilt and circling. Pathological examinations revealed abundant Sarcocystic cysts in the skeletal muscle and myocardium with mild myositis, and numerous schizonts and sarcocysts with severe multifocal granulomatous T-lymphocytic infiltration in the central nervous system. A Sarcocystis calchasi-specific gene was detected in the muscle and brain. This case indicates S. calchasi was distributed in Japan and caused severe encephalitis to rock pigeons.