the courts. The lesions I will describe are named to correspond with terminology 
suggested for rodent hepatic lesions induced by experimental carcinogens. 
There is a sequence of changes in the liver which takes place from the action 
of a carcinogen. One of the early lesions (although there is some debate on this) is the 
formation of chromatically-altered foci, or changes in color of the parenchymal cells. 
Figure 5 shows an area of chromatic change^in the center of some hepatocytes 
with cytoplasmic inclusions (probably containing fat). The cells have greater affinity for 
the stain than adjacent cells. This is significant and should not be ignored. The lesion is 
called a basophilic focus because its color is blue after staining with hematoxylin and 
eosin (H&E). These chromatically altered foci can be quite large and easily seen at low 
magnification. In fact, some of these foci can be detected with a hand lens, regardless of 
whether they are basophilic or eosinophilic (red with H&E). 
Figure 6 illustrates a lesion at low magnification visible not only with a hand 
lens, but with the naked eye. One easily can recognize a distinct tumor in this 
photomicrograph with a well-defined outline. As you will see later, this lesion is not very 
different from the one in the preceding figure, but its cellular characteristics and well- 
defined configuration elevate it to something more in the nomenclatural heirarchy of 
these lesions. It is designated a hepatocellular adenoma; the hepatic cords outside the 
tumor are compressed. The cords in the tumor are virtually at right angles to the cords 
outside the tumor. As the mass increases in size, it does so at the expense of adjacent 
tissue. When this happens, and when certain other characteristics are evident, the lesion 
is designated a hepatocellular adenoma. With mammals, and man primarily, it would be 
considered a benign lesion. Unfortunately designation as benign or malignant in fish is not 
possible using only histologic criteria. If I showed a higher magnification, we could see 
evidence of cell replication from the presence of mitotic figures. 
Vacuolated hepatocyte foci are common in livers of Boston Harbor winter 
flounder and frequently contain other cells in the vacuolated cell areas. These cells are 
chromatically, cytologically, and organizationally different from the vacuolated cells. In 
many instances, they have the appearance of early neoplasms. Seventy-seven percent of 
the winter flounder examined from Boston Harbor have vacuolar cell lesions. That is a 
very significant number, especially because there appears to be a relationship between the 
vacuolar lesions and the neoplastic ones. If the presence of vacuolar cells signifies 
eventual transformation to neoplastic cells, 77 percent is a very alarming number. 
Figure 7 shows some chromatically different cells together with vacuolated 
cells. Some pathologists might not designate the lesion as neoplastic, probably because 
they have not examined adequate numbers of histologic sections to interpret the 
significance of the lesion with respect to other neoplastic ones. In Figure 7, the 
neoplastic cells are trying to form bile ducts. Their destiny, if they are derived from 
precursors of duct epithelial cells, is to form bile ducts. 
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