606 THE LIVER. 



sometimes thin. They are believed to be formed by dilatation of the 

 liver capillaries, with subsequent thickening of their walls and atrophy 

 of the adjacent liver cells. By the organization of clots within the blood 

 cavities these tumors may be partially or entirely converted into masses 

 of dense fibrous tissue. 



Small fibromata and lipomata have been described, also fibroneuromata 

 of the sympathetic. 



Adenomata of the liver are of not infrequent occurrence. They are 

 sometimes small and circumscribed, sometimes very large and multiple. 

 They present two tolerably distinct types of structure. In one form the 

 tissue presents essentially the same structure as normal liver tissue, ex- 

 cept that the arrangement of the cells is less uniform and the cells are 

 apt to be larger. They look like little islets of liver tissue, sometimes 

 encapsulated and sometimes not, lying in the liver parenchyma. In the 

 other form the cells are less like liver cells, are frequently cylindrical, 

 and are arranged in the form of irregular masses of tubular structures 

 with more or less well -defined lumina. These tumors are sometimes 

 large and multiple, and in one case described by Greenfield there were 

 metastatic tumors in the lungs. These tubular adenomata are in some 

 cases so closely similar to some of the carcinomata as to be scarcely dis- 

 tinguishable from them, and seem, indeed, to merge into them. ' 



Aberrant nodules of adrenal tissue have been found in the liver and 

 may be mistaken for adenomata. Cysts may develop in adenomata. 2 



Carcinomata are the most common and important of the liver tumors, 

 and may be primary and secondary. Primary carcinomata of the liver are 

 probably developed from the epithelium of the gall ducts, and in some 

 cases are arranged along the larger trunks. The cells are usually poly- 

 hedral, sometimes cylindrical, and may be arranged irregularly in alveoli 

 or form more or less well-defined tubular structures. 



Secondary carcinoma of the liver, which is by far the most common, is 

 usually due to the dissemination in the organ of tumor cells from carci- 

 nomata of the stomach, intestines, pancreas, or gall bladder. But it 

 may be the result of metastases from the mamma, oesophagus, uterus, 

 and various other parts of the body. In secondary carcinoma the cells 

 resemble more or less closely the type of those forming the primary tumor.- 



The form in which the carcinoma in the liver occurs varies consider- 

 ably. Sometimes the tumors are single, but more often multiple (Fig. 

 370) ; they may be very large, or so small as to be scarcely visible to the 

 naked eye ; very frequently numerous small nodules are grouped in the 

 periphery of a larger one. They are sometimes deeply embedded in the 

 liver, sometimes they project from the surface. The liver is frequently 

 and sometimes enormously enlarged. The nodules are usually whitish or 

 yellowish or pink in color or bile-stained, and they are often the seat of 

 haemorrhages, and may become softened at the centre, forming cysts filled 



1 Sokoloff has described an adeno-carcinomaof the liver with ciliated cells, Virchow's 

 Arch., Bd. clxii., p. 1, bibliography of allied tumors. See also Herxheimer, Cbl. f. 

 Path., Bd. xiii., 1902, p. 705. 



s See for cyst formation in the liver Dmochowski and Janoicski,, Ziegler's Beitr. z. 

 path. Anat., Bd. xvi., p. 102. 



