The histogenesis of primary hepatic carcinoma.

The existence of hepatocellular and cholangiocellular carcinomata, arising from liver cells and bile duct epithelium respectively, has long been recognized, although the proportions of each type have varied in different series. Gustafson (1937) reported 39 liver cell and 11 bile duct tumours amongst 62 cases of primary liver carcinoma based on 24,400 necropsies, and Wilbur, Wood, and Willett (1944) described 45 hepatomas and four cholangiomas. This predominance of liver cell tumours is also stressed by Counseller and Mclndoe (1926), Loesch (1939), and Hoyne and Kernohan (1947). On the other hand, Fried (1924) described four cholangiomas and one hepatoma, while Karsner (1911) and Cunningham (1943) reported a preponderance of cholangiomas. The existence of a combined tumour, consisting of hepatocellular and cholangiocellular elements, has been postulated comparatively recently. Milne (1909) and Beattie and Donaldson (1912) only recognized two types, while Pirie (1921) reported five tumours of doubtful or mixed origin amongst 36 cases of primary hepatic carcinoma. Gustafson (1937) described two cases of "intermediate or dual origin" in his series and this combined carcinoma has also been described by Warvi (1944). Allen and Lisa (1949), reporting five cases of combined liver cell and bile duct tumours amongst 35 cases of primary hepatic carcinoma, described three possible combinations, namely, separate hepatoand cholangiocellular tumours in the same liver, separate tumours which intermingle, and individual masses which display both features so intimately associated that they can only be interpreted as arising from the same site. Three of their cases fell within the last group, while Campbell (1949) described four examples of mixed tumour amongst 22 cases of spontaneous hepatocellular and cholangiocellular carcinoma in ducks. The occurrence of three apparently mixed hepatoand cholangiocellular tumours in an un-