TONGUE, DISEASES OF. The most important disease of the tongue is cancer which may affect any part but is liable to occur at the sides, when the organ is irritated by a carious tooth or an ill-fitting denture. It shows itself as a hard raised ulcer and microscopically is a squamous cell carcinoma (see TUMOURS). The lymphatic glands in the neck and beneath the jaw are early affected by extension of the disease. At first the disease causes little more than discomfort and some pain in feed ing but soon the extension leads to fixation and the jaws often can not be separated more than to admit passage of a lead pencil be tween the teeth. The secondary growths in the neck and beneath the jaw increase in size rapidly and may break down leading to a foul ulcer or to haemorrhage from invasion of one of the great blood vessels in the neighbourhood. The great salivation that accompanies cancer of the tongue is one of its greatest trials. The natural duration of the disease from first observation to death is on an average little over a year. Until recently the sole possible form of treatment was surgery consisting in removal of the tongue and of cervical glands in a single or a divided operation. When the growth affects the anterior portion of the organ this operation meets with a fair amount of success but when the side or back of the tongue is affected the operation is serious and the results are poor so far as concerns prolonged duration of life. At the present time treatment by radium in the form of radium needles or minute "seeds" containing radium emanation is practised. Sufficient time has not passed for dogmatic statement but the re sults appear to compare favourably with those of surgery. When ever a carious tooth irritates the tongue the dentist's services should be sought. Other diseases of the tongue of importance are syphilitic. In leukoplakia the epidermis becomes thick and white in patches over the dorsum ; the condition is of great importance since cancer is liable to begin in such leukoplakic patches. The other syphilitic condition is gumma (see VENEREAL DISEASES), a condition difficult to diagnose from cancer except by the course it takes. As procrastination is fatal if the condition be cancer in
reality, and a person from whom the tongue has been removed is not greatly inconvenienced thereby, the treatment should be based upon the more serious assumption.
Hardly coming under the definition of diseases are those morbid states of the tongue met with in various disorders involving other parts of the body. The appearances noted when the physician "looks at the tongue" vary according to the degree to which epi thelial cells cover the papillae and the degree to which saliva is formed. In the white or plastered tongue of acute febrile disease the papillae are covered by a thick layer of proliferated epithelium in which are many micro-organisms, and the mouth is dry. If the fever continues and intensifies the coat peels off and a red, dry, denuded tongue results. If, on the contrary, improvement in the patient's condition is taking place the tongue begins to "clean" at the tip and edges, i.e., secretion of saliva recommences and the white coat is removed by rubbing against the teeth and palate. The flabby, tooth-indented tongue of dyspepsia, the red, cracked tongue of diabetes, the tremulous tongue of alcoholism, the later ally displaced tongue indicating paralysis as in cerebral apoplexy are other examples of the information which examination of the tongue affords to the instructed eye (see Howship Dickinson, The Tongue in Disease, London, 1888).
So-called "thrush" (aphtha) occurs over the tongue and mouth of babies in poor condition, usually from faulty feeding ; it is caused by the growth of yeast moulds in the superficial layers of the epitheiium and is favoured by an acid reaction of the saliva and mucus in the mouth. The treatment is rectification of the feeding and local application of a mixture of myrrh, borax and honey. Other abnormal conditions of the tongue occur such as small ulcerations in some cases of advanced pulmonary tubercu losis and inflammatory masses in actinomycosis (q.v.).