Histopathological classification of spontaneous hyperplastic liver nodules in slaughtered swine

Thirty-two cases of spontaneous hyperplastic nodules of the liver found in slaughtered swine were classified on the basis of their histological characteristics into two main types, non-fibrous and fibrous nodules, according to their content of fibrous tissue. These two main types were further divided into two subgroups: type 1, a nodule mainly consisting of liver cells arranged in a single liver cell plate, and type 2 nodule with a multiple liver cell plate architecture. All 12 fibrous nodules were of type 2; of the 20 non-fibrous nodules 9 were of type 1 and 11 were type 2 or intermediate. The histopathology of these lesions is discussed in relation to pre-neoplastic and neoplastic characters.