There are, of course, many varieties of solitary tumors of the skin; there are found fibroids, fatty tumors, lymphoid tumors, neoplasms originating from the blood or lymph vessels, endotheliomata, wens, dermoid tumors, sarcoids of various varieties, and a number of inflammatory conditions, of which chancre and gummata are the more prominent. With the exception of the last two just named, the diagnosis is usually easy, for we find that nearly all of these growths present themselves as definitely encapsulated, slowly growing tumors, that only rarely ulcerate through the skin, and then only after they have existed for many years. All of them lack the stony hardness at the edge that is characteristic of the carcinomata, and also the firm attachments to the underlying and overlying structures. Sarcomata may more nearly resemble these growths, for at first they are often found to be pretty definitely encapsulated, and hence freely movable.

Chancre

At times it is extremely difficult to make a differential diagnosis between a chancre and a rapidly growing nodular cancer (Figs. 60, 61), for both have the same cartilaginous resistance, and ulceration often takes place in the center of each in about the same way. The observance of a number of facts will, however, aid in making a diagnosis. In the first place, the age of the patient is a great factor, for cancer is infrequent in the young, while chancre usually does not occur in the old, although it may, of course, do so. Second, the location of the growth is of some aid, for chancres are rare except upon the penis,'lips, or fingers, although they may, of course, occur upon any part of the body. Cancer is rather rare upon the upper lip, and practically never occurs upon either lip in a woman. Third, the growth of a chancre is usually very much more rapid than that of a cancer, a diameter of 2 cm. being not infrequently obtained in less than two weeks; and fourth, the neighboring glands usually swell within a month after the initial appearance of a specific lesion, which is not found in cancer. In cases of doubt, the spirochete should be searched for with the dark field illuminator; this instrument is much more satisfactory than the examination of stained specimens. Where none of these methods are available, salvarsan should be administered intravenously, and, if the growth disappears, it was undoubtedly luetic.

Fig. 61.-Chancre of the Hp of one month's duration. (Author's collection).

Gumma

Rarely a gumma may present symptoms that make it practically impossible to differentiate from cancer. The author has recently seen two cases of tumors upon the nose, both occurring in people past 40, who presented no other evidences of syphilis (Fig. 62). In both of these eases there was a raised, extremely hard edge, with dilated blood vessels, no ulceration for a number of months, and no marked inflammation present. Both cases were considered to be cancerous, but in both cases sections showed a typically gummatous structure, and both cleared up under salvarsan. As a general rule, a gumma is inflammatory and soon breaks down, forming a punched-out ulcer that has a soft edge (Fig. 63). There are three ways of making a differential diagnosis in doubtful cases-first and surest, by taking a piece of tissue for examination; second, by finding other signs of syphilis, either clinically or by laboratory methods; and last, by the so-called therapeutic test-namely, the intensive administration of antisyphilitic treatment.

Fig. 62.-Gumma of the nose, with a hard-rolled edge simulating carcinoma. (Author's collection).