The disease probably originates before birth, although it may not make its appearance till adolescence or even till adult life.  It is sometimes met with in several members of one family.  It is recognised clinically by the presence of multiple tumours in the course of the nerves, and sometimes by palpable enlargement of the superficial nerve-trunks (Fig. 86).  The tumours resemble the solitary trunk-neuroma, are usually quite insensitive, and many of them are unknown to the patient.  As a result of injury or other exciting cause, however, one or other tumour may increase in size and become extremely sensitive; the pain is then agonising; it is increased by handling, and interferes with sleep.  In these conditions, a malignant transformation of the fibroma into sarcoma is to be suspected.  Motor disturbances are exceptional, unless in the case of tumours within the vertebral canal, which press on the spinal medulla and cause paraplegia.

[Illustration:  FIG. 86.—­Diffuse enlargement of Nerves in generalised Neuro-fibromatosis.

(After R. W. Smith.)]

Neuro-fibromatosis is frequently accompanied by pigmentation of the skin in the form of brown spots or patches scattered over the trunk.

The disease is often stationary for long periods.  In progressive cases the patient becomes exhausted, and usually dies of some intercurrent affection, particularly phthisis.  The treatment is restricted to relieving symptoms and complications; removal of one of the tumours is to be strongly deprecated.

In a considerable proportion of cases one of the multiple tumours takes on the characters of a malignant growth ("secondary malignant neuroma,” Garre).  This malignant transformation may follow upon injury, or on an unsuccessful attempt to remove the tumour.  The features are those of a rapidly growing sarcoma involving a nerve-trunk, with agonising pain and muscular cramps, followed by paralysis from destruction of the nerve fibres.  The removal of the tumour is usually followed by recurrence, so that high amputation is the only treatment to be recommended.  Metastasis to internal organs is exceptional.

[Illustration:  FIG. 87.—­Plexiform Neuroma of small Sciatic Nerve, from a girl aet. 16.

(Mr. Annandale’s case.)]

There are other types of neuro-fibromatosis which require brief mention.

The plexiform neuroma (Fig. 87) is a fibromatosis confined to the distribution of one or more contiguous nerves or of a plexus of nerves, and it may occur either by itself or along with multiple tumours of the nerve-trunks and with pigmentation of the skin.  The clinical features are those of an ill-defined swelling composed of a number of tortuous, convoluted cords, lying in a loose areolar tissue and freely movable on one another.  It is rarely the seat of pain or tenderness.  It most often appears in the early years of life, sometimes in relation to a pigmented