lly in
cold weather.

Unlike the other forms of naevi, the cutaneous variety shows little
tendency to disappear, and it is especially persistent when associated
with overgrowth of the epidermis and of the hairs--_naevoid mole_.

The _treatment_ of the cutaneous naevus is unsatisfactory, owing to the
difficulty of removing the naevus without leaving a scar which is even
more disfiguring. Very small naevi may be destroyed by a fine pointed
Paquelin thermo-cautery, or by escharotics, such as nitric acid. For
larger naevi, radium and solidified carbon dioxide ("CO_2 snow") may be
used. The extensive port-wine stains so often met with on the face are
best left alone.

The _subcutaneous naevus_ is comparatively rare. It constitutes a
well-defined, localised tumour, which may possess a distinct capsule,
especially when it has ceased to grow or is retrogressing. On section,
it presents the appearance of a finely reticulated sponge.

Although it may be noticed at, or within a few days of, birth, a
subcutaneous naevus is often overlooked, especially when on a covered
part of the body, and may not be discovered till the patient is some
years old. It forms a rounded, lobulated swelling, seldom of large size
and yielding a sensation like that of a sponge; the skin over it is
normal, or may exhibit a bluish tinge, especially in cold weather. In
some cases the tumour is diminished by pressing the blood out of it, but
slowly fills again when the pressure is relaxed, and it swells up when
the child struggles or cries. From a cold abscess it is diagnosed by the
history and progress of the swelling and by the absence of fluctuation.
When situated over one of the hernial openings, it closely simulates a
hernia; and when it occurs in the middle line of the face, head, or
back, it may be mistaken for such other congenital conditions as
meningocele or spina bifida. When other means fail, the use of an
exploring needle clears up the diagnosis.

_Mixed Naevus._--As its name indicates, the mixed naevus partakes of the
characters of the other two varieties; that is, it is a subcutaneous
naevus with involvement of the skin.

It is frequently met with on the face and head, but may occur on any
part of the body. It also affects parts covered by mucous membrane, such
as the cheek, tongue, and soft palate. The swelling is rounded or
lobulated, and projects beyond the level of its surroundings. Sometimes
the skin is invaded by the naevoid tissue