AS fibrous tissue is frequently the product of inflammation we may expect that the demarcation between inflammatory new-formations and fibromas is not always easy to make. Elephantiasis arabum is sometimes regarded as a simple tumour, although more properly belonging to the infective tumours. There are cases, however, of local enlargement of the skin, which have not the regular course of elephantiasis, and which have more apparent analogies with tumours. To such cases Paget's name of " Cutaneous outgrowth " is applicable. There are cases also in which, with or without thickening of the cutis, there is a definite encapsuled tumour, composed of soft connective tissue, beneath the skin. Such tumours occur chiefly in the external organs of generation, and may attain large dimensions, one observed by the author weighing fifteen pounds. (See Elephantiasis).
Fibroma molluscum or Multiple fibroma of the skin are terms applied to cases in which we have multiple isolated tumours beginning as little growths of connective tissue in diverse regions in the skin, and afterwards growing out and becoming pendulous. Thus we may have hundreds of more or less pendulous tumours in various parts of the body (see illustration in section on Tumours of the Skin). This purely fibrous molluscum must be carefully distinguished from mol-luscum contagiosum, a totally different disease, which will be considered in the section on Diseases of the Skin.
These multiple fibromata have been made the subject of special study by Reck-linghausen, who found them in two cases associated with multiple tumours of the nerves. The tumours of the nerves formed usually oval swellings in their course, and were composed of comparatively soft connective tissue in which the nerve-fibres were embedded. These tumours are frequently described under the name of Neuroma, but as they are really fibrous tissue tumours they are to be regarded as false neuromata. The term Neurofibroma or fibroneuroma is more correctly applied. In Recklinghausen's cases the tumours of the skin were also found in their origin to be connected with nerve-stems, growing from the nerve sheath, although in growing they frequently involved the sheaths of neighbouring canals, such as blood-vessels and sweat-glands. The tumours of the nerves have frequently a plexiform character, being formed by enlargement of the sheaths of a plexus of nerves. A similar character is sometimes presented by the cutaneous tumours, and may assist in their diagnosis. Whether Recklinghausen's view applies generally to the multiple fibroma of the skin or not, remains to be determined. It is confirmed by Kriege and Westphalen, while its universal applicability is questioned by Philippson.
The Mucous polypus is a condition which lies on the borderland between inflammatory hypertrophy and true tumour formation. It consists of mucous membrane in which there is frequently a considerable new-formation of gland-tissue, so that in some cases the term Adenoma is warranted. The lesions are usually small in size, and are met with chiefly in the rectum, in the nares, and in the uterus (which see).
Fig. 70. - Fibroma originating in connection with fascia. x350.
Hard Fibromas or true Fibromas are exceedingly dense tumours composed of firm connective tissue tightly interlaced and resembling tendon in its structure. On section they show a brilliant white surface, and often a concentric arrangement of the connective-tissue bundles.
We do not include here the uterine fibromas, which are really muscular tumours, and will be described as such. Fibromas are frequent in connection with periosteum and bone, especially on the jaws. Growing from the periosteum they are sometimes intimately connected with the bone, which may be as if buried in the tumour. Sometimes the fibroma originates inside a bone. Fibromas also occur on fascias (see Fig. 70) and membranes, as the dura mater, and are not uncommon in the mamma and ovary. Just as dense connective tissue formed in chronic inflammation may become calcified, so may dense fibromas be partially infiltrated with lime salts. They sometimes undergo partial ossification, or they may be mixed with bone, cartilage, or gland tissue.
Virchow's Geschwulste, i.; Morton and Coats, Glasg. Med. Jour., iii., 145, 1870; Recklinghausen, Die multiplen Fibrome der Haut, 1882; Kriege, Virch. Arch., cviii. 466; Westphalen, do., ex. 29; Philippson, do., 602.