Swine lymphoid and myeloid neoplasms in Italy.

In the decade 1973-1982, data from all the principal diagnostic centers in Italy reveals that swine lymphoid and myeloid neoplasms (LMN) have been observed only few times (78 cases). In a 25-year period (1950-1984) 48 cases were diagnosed in our Institute, among which all the known forms of LMN, including the most uncommon such as multiple myeloma (1) and myeloid forms (4) including 1 chloroma and 1 erythraemic neoplasm. The incidence remains low; 1.17% of the diseased swine sent for necropsy, with no significant increase during the years. In the same period the incidence of other neoplasms was 1.14%. Also the data from the abattoir of Bologna confirm a low incidence: in the last 2 years lymphoid neoplasms were observed only twice among 130,000 slaughtered pigs (15 cases per million). This incidence is therefore similar to that noticed in slaughterhouses in other European countries and in the U.S.A. As for the anatomohistopathological features, lymphosarcoma presents a constant autochthonous production of immature collagen fibrils, but the degree of this production has no significant relation with either the macroscopic type of lesions, nodular or infiltrating (diffuse), or the level of cellular differentiation. Diffusely haemorrhagic lesions were observed in a relatively high percentage (14%) of lymphosarcomas. The incidence of myeloid neoplasms is relatively high compared with that of lymphosarcomas: from 5% of Italian cases as a whole to 14% of the cases studied in our Institute. This confirms that the pig is second to the dog as a domestic animal showing most of these myeloid neoplasms.