Immunohistological studies on primary reticulosis of the canine brain.

Brains of 17 dogs with primary reticulosis, and of two with metastatic and one with primary lymphosarcoma, were examined by immunohistologic techniques with antisera against the major immunoglobulin classes of the dog. On the basis of immunoglobulin in tumour cells, two reticuloses were reclassified as primary lymphosarcomas of the brain. The tumour cells in three other dogs with neoplastic reticulosis and in six dogs with microgliomatosis did not contained immunoglobulin. Many cells in inflammatory reticulosis were immunoglobulin-bearing. Although some of these lesions could have been lymphosarcomas, insufficient data were available to ascertain either an inflammatory or a neoplastic nature. It was concluded that some lesions previously classified as reticulosis are in fact primary histiocytic lymphosarcomas of the brain, while others may be true reticulosarcomas.