Plexiform Sarcoma Or Cylindroma is a name applied to a form of tumour whose relations are somewhat obscure, and it probably includes more than one kind. The peculiarity of the tumour is the existence of cylinders and rounded structures having a hyaline character, like mucous tissue. In the centre of the cylinder there is often a blood-vessel, so that the hyaline material clothes it like a mantle. Then, between the cylinders of hyaline material there are frequently masses of cells which may form long processes, so as to give a close resemblance to cancer, to whose cells these may also conform in general appearance.

Pigmented Sarcoma. The cells are spindle shaped. Some are deeply pigmented, x 350.

Fig. 102. - Pigmented Sarcoma. The cells are spindle-shaped. Some are deeply pigmented, x 350.

The origin of these cylinders is not perfectly clear. In some cases it may be that we have a combination of sarcoma and myxoma, but this does not account for the peculiar form of the cylinders. A more probable explanation is that the cylinders arise by hyaline or mucous degeneration of the adventitia of the bloodvessels, and this is confirmed by the fact that they are often arranged around the vessels. In this way we should have a sarcoma in which a peculiar transformation occurs in the external coats of the vessels. It is on this view that the name p/exi-form awjiosarcoma is applied to this form of tumour.

The tumour as a whole is often of a gelatinous appearance, or it may be that the gelatinous material is seen to be in separate spaces throughout the tumour. It occurs in the orbit and its neighbourhood, or the upper and lower jaws; it may form part of the constituents of tumours of the parotid, and it is also found in the brain and its membranes and the peritoneum, where it may grow to a large size.

Besides these .forms of sarcoma several others are sometimes distinguished and designated by special names. Thus we have Alveolar sarcoma in which the cells, which are generally round and frequently large, are arranged in loculi, so that both in the characters of the cells and their arrangement there may be a resemblance to cancer. The place of origin and the intimate relation between the cells and the loculi are generally sufficient to make the diagnosis clear.

The Osteoid chondroma and Osteoid sarcoma are closely allied forms of tumour of bone. In both there is a great tendency to the formation of osseous tissue, often of imperfect structure. The recent and growing parts of the tumours are composed of cells like those of ossifying cartilage, or of spindle-shaped or stellate cells with stiff fibrous intercellular substance.

The Psammoma is often regarded as a variety of sarcoma. No doubt spindle-celled sarcomas sometimes contain calcareous particles such as these already described. With less justification the Glioma is sometimes included with the sarcomas. The term Endothelioma is used by some to designate tumours which have a structure indistinguishable from carcinomas, but arise in presumably non-epithelial structures. We prefer to include them among the cancers, where they will be described.

Literature

Virchow, Geschwiilste, 1864-65, ii., 170; Paget, Lect. on surg. path., 3rd ed., 1870, p. 544; Billroth, Lect. on surg. path., Syd. Soc. transl., 1878, ii., 401; Butlin, Internat. Encycl. of Surg., 1884, iv., 600, and Sarcoma and Carcinoma, 1882; Bizzozero, Wien. med. Jahrb., 1878, p. 4; Ackermann, Volkmann's Vortriige, Nos. 233, 234, 1883; Huber (Chloroma), Arch. d. Heilk., xix., 1878, p. 129; Chiari (Chloroma), Zeitschr. f. Heilk., iv., 1883. Cylindroma - Billroth, Die Entwick. der Blutgefasse, 1856; Virch. Arch., xvii., 364; Sattler, Ueber die sogenannte Cylindrome, 1874; Ewetzky, Virch. Arch., lxix.; Waldeyer, do., Iv.; Friedlander, do., lxvii. . . . Oppenheimer (Formation of pigment), Virch. Arch., cvi., 515.