GASEOUS TUMORS OF THE SCALP.
The most common of these tumors is ordinary emphysema, which may result from injury to the upper and lower air passages. Thus fractures of the nasal bones or of the base of the skull may permit of distention of the subcutaneous cellular tissue by forcible inspiration of air. Emphysema of the scalp may be a valuable diagnostic feature in certain instances, as after fractures of the upper bones of the face. When connected with a wound it should be enlarged in order to permit the escape of contained air. Otherwise these puffy swellings disappear spontaneously by absorption of air into the veins. In cases of malignant or gangrenous emphysema early and numerous incisions are necessary, after which antiseptic solutions, etc., should be used.
Pneumatocele.
—A pneumatocele is a chronic gaseous tumor, being a cavity distended with air which has escaped from the cells of the underlying bone, bounded on the outside by the scalp and beneath by the cranium. They are found about the mastoid or the frontal regions. Not more than three dozen cases are on record. In consistency these tumors are elastic, while the escape of air upon pressure is sometimes heard on auscultation. Their explanation is usually a defect of the inner wall of the mastoid cells, through which air may be forced from the pharynx through the middle ear by violent effort, or similar defect in the ethmoidal cells by which air is forced anteriorly. Bony defects which might permit this condition are seen in a small percentage of craniums.
Treatment.
—The best results in the way of treatment have been achieved by puncture, with the injection of weak iodine solution ([Fig. 366]).
TUMORS OF THE SCALP.
Tumors of the scalp may be divided into the congenital and the acquired, as well as into the benign and malignant.
Of the congenital tumors the dermoids are of most interest. Originally the dura and the skin were in contact, and the cranial bones develop later between them. This explains the occurrence of dermoids either beneath or outside of the bone or their simultaneous appearance and possible connection. Many of the so-called atheromatous cysts or wens are of dermoid origin. Those which are extracranial need only antiseptic incision or excision. It will often be sufficient to split such a cyst with a bistoury, after which each half of the sac can be detached from the bed in which it has lain. Should intracranial connection be discovered the bone chisel and sharp spoon will be necessarily called into employment. Some of these dermoids perforate into the orbit, and may have to be followed into that location.
Most varieties of tumors, benign or malignant, may be met with in this region. Subcutaneous collections of fat are not so common, nor are fibromas. Various bony growths may be met, while in certain cases the signs of brain pressure are to be explained only by their extension within the cranium.