otherwise healthy, and it may be innocent or malignant.

_The innocent_ form is usually fibrous or myxomatous, and is definitely
encapsulated. It may become cystic as a result of haemorrhage or of
myxomatous degeneration. It grows very slowly, is usually elliptical in
shape, and the solid form is rarely larger than a hazel-nut. The nerve
fibres may be spread out all round the tumour, or may run only on one
side of it. When subcutaneous and related to the smaller unnamed
cutaneous nerves, it is known as a _painful subcutaneous nodule_ or
_tubercle_. It is chiefly met with about the ankle, and most often in
women. It is remarkably sensitive, even gentle handling causing intense
pain, which usually radiates to the periphery of the nerve affected.
When related to a deeper, named nerve-trunk, it is known as a
_trunk-neuroma_. It is usually less sensitive than the "subcutaneous
nodule," and rarely gives rise to motor symptoms unless it involves the
nerve roots where they pass through bony canals.

A trunk-neuroma is recognised clinically by its position in the line of
a nerve, by the fact that it is movable in the transverse axis of the
nerve but not in its long axis, and by being unduly painful and
sensitive.

[Illustration: FIG. 85.--Amputation Stump of Upper Arm, showing bulbous
thickening of the ends of the nerves, embedded in scar tissue at the
apex of the stamp.]

_Treatment._--If the tumour causes suffering it should be removed,
preferably by shelling it out from the investing nerve sheath or
capsule. In the subcutaneous nodule the nerve is rarely recognisable,
and is usually sacrificed. When removal of the tumour is incomplete, a
tube of radium should be inserted into the cavity, to prevent recurrence
of the tumour in a malignant form.

_The malignant neuroma_ is a sarcoma growing from the sheath of a nerve.
It has the same characters and clinical features as the innocent
variety, only it grows more rapidly, and by destroying the nerve fibres
causes motor symptoms--jerkings followed by paralysis. The sarcoma tends
to spread along the lymph spaces in the long axis of the nerve, as well
as to implicate the surrounding tissues, and it is liable to give rise
to secondary growths. The malignant neuroma is met with chiefly in the
sciatic and other large nerves of the limbs.

The _treatment_ is conducted on the same lines as sarcoma in other
situations; the insertion of a tube of radium after removal of the
tumour dim