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.
|