Non-T, non-B lymphoblastic lymphoma in two pigs.

The histological, immunological and ultrastructural observations on two cases of non-T, non-B lymphoblastic lymphoma are reported. Although the neoplastic cells had neither sheep erythrocyte (E) receptors for T lymphocytes nor surface membrane immunoglobulin (SIg) for B lymphocytes, terminal deoxynucleotidyl transferase (TdT) was demonstrated in the nuclei of many or some neoplastic cells. Ultrastructurally the neoplastic cells showed no specific features except desmosome-like junctions. The morphological and immunological findings suggest that the present cases are derived from immature lymphoid cells or stem cells of the bone marrow. The significance of the junctions is discussed and such structures may be common in various mesenchymal cells.