This name has been applied by Virchow to tumours into the structure of which a number of very different tissues enter. The name is derived from 15 Teratoma 109 , a monster. The tumour contains various structures of the body as if from an ill-arranged foetus. Thus, we may have in such tumours, skin, bone, muscle, glands, nervous tissue.

Some of these tumours arise by the abnormal inclusion of a portion of a double monster (see p. 39). They are most frequently met with in positions where double monsters are usually attached to each other, namely, in the sacral region or further up the back, and in the head and neck. They are also somewhat frequent in the ovary where they may arise by an irregular developmental process, the ovum endeavouring to develop some of the perfect tissues of the body.

The Sacral teratomas and those of the head and neck are the more typical ones. The former are frequently of large size (see Fig. 96).

Congenital sacral teratoma.

Fig. 96. - Congenital sacral teratoma.

They frequently contain pieces of bone which simulate the bones of the foetus, also brain substance. Not infrequently they contain cysts, and may be indeed chiefly composed of these. The walls of the cysts recall the structure of the skin, sometimes with hairs, etc., and of mucous membranes, and their contents are sebaceous matter and mucus. Besides cysts the tumour commonly contains much adipose tissue, glandular structures of somewhat indefinite character, and voluntary muscle.

The teratomas of internal organs do not usually represent such complete systems or so many different tissues as the sacral. They are most frequent in the ovaries, but also occur in the peritoneum, testes, lungs, and so on. The dermoid cysts already considered are the chief representatives of this group in internal organs.

It must be confessed that the exact position of these tumours cannot be regarded as fully determined. A case examined by the author has some peculiar features which approximate it to the class of true tumours. The child lived for two years after birth, and the tumour became much larger, even in proportion to the growth of the child during that period. Most of the tissues mentioned above were present, namely, cysts of the dermic and mucoid character, adipose tissue, voluntary muscle, gland tissue and bone. A striking peculiarity, and one which constitutes the chief divergence from other cases of the kind, was the presence of cancerous tissue. Not only was this tissue present in the tumour, but there were numerous secondary tumours of typically cancerous structure in the liver. (See as to sacral tumours, Freyer, Virch. Arch., 1873, lviii., p. 509; and Liitkemiiller, Strieker's Jahrbiicher, 1875, p. 66).