The subject of sarcomata of the skin is still in a greatly confused condition. It is not yet definitely known whether the multiple pigmented growths are derived from the epithelium or from the mesoblastic structures, and neither is it definitely decided whether many of the alveolar growths are endotheliomata or sarcomata. Again, the dividing line between the sarcomata and certain so-called cases of mycosis fungoides and lymphoid tumors is a very shadowy one, and, last, certain cases of sarcomata cannot be definitely distinguished from certain of the sarcoid tumors. Until these growths can be distinguished, or until they can all be proven to be merely different forms arising from the same cause, the subject must of necessity remain hazy.
In a short chapter of this kind it seems best not to attempt to reconcile all of these differences, but rather to point out that they do exist, and to describe the well-known and typical forms of this very serious type of cutaneous neoplasm.
The following classification is tentatively adopted:
Solitary lesions. Round-celled. Spindle-celled. Giant-celled.
Multiple lesions. Round-celled. Melanotic.
Pigmented hemorrhagic (Kaposi).
Subcutaneous type of Darier and Roussy. Nodular type on extremities.