Cellulitis is an acute affection resulting from the introduction of some organism—commonly the pyogenes—into the cellular connective tissue of the integument, intermuscular septa, tendon sheaths, or other structures. Infection always takes place through a breach of the surface, although this may be superficial and insignificant, such as a pin-prick, a scratch, or a crack under a nail, and the wound may have been healed for some time before the inflammation becomes manifest. The cellulitis, also, may develop at some distance from the seat of inoculation, the organisms having travelled by the lymphatics.
The virulence of the organisms, the loose, open nature of the tissues in which they develop, and the free lymphatic circulation by means of which they are spread, account for the diffuse nature of the process. Sometimes numbers of cocci are carried for a considerable distance from the primary area before they are arrested in the lymphatics, and thus several patches of inflammation may appear with healthy areas between.
The pus infiltrates the meshes of the cellular tissue, there is sloughing of considerable portions of tissue of low vitality, such as fat, fascia, or tendon, and if the process continues for some time several collections of pus may form.
Clinical Features.—The reaction in cases of diffuse cellulitis is severe, and is usually ushered in by a distinct chill or even a rigor, while the temperature rises to 103°, 104°, or 105° F. The pulse is proportionately increased in frequency, and is small, feeble, and often irregular. The face is flushed, the tongue dry and brown, and the patient may become delirious, especially during the night. Leucocytosis is present in cases of moderate severity; but in severe cases the virulence of the toxins prevents reaction taking place, and leucocytosis is absent.
The local manifestations vary with the relation of the seat of the inflammation to the surface. When the superficial cellular tissue is involved, the skin assumes a dark bluish-red colour, is swollen, œdematous, and the seat of burning pain. To the touch it is firm, hot, and tender. When the primary focus is in the deeper tissues, the constitutional disturbance is aggravated, while the local signs are delayed, and only become prominent when pus forms and approaches the surface. It is not uncommon for blebs containing dark serous fluid to form on the skin. The infection frequently spreads along the line of the main lymph vessels of the part (septic lymphangitis) and may reach the lymph glands (septic lymphadenitis).
With the formation of pus the skin becomes soft and boggy at several points, and eventually breaks, giving exit to a quantity of thick grumous discharge. Sometimes several small collections under the skin fuse, and an abscess is formed in which fluctuation can be detected. Occasionally gases are evolved in the tissues, giving rise to emphysema. It is common for portions of fascia, ligaments, or tendons to slough, and this may often be recognised clinically by a peculiar crunching or grating sensation transmitted to the fingers on making firm pressure on the part.
If it is not let out by incision, the pus, travelling along the lines of least resistance, tends to point at several places on the surface, or to open into joints or other cavities.
Prognosis.—The occurrence of septicæmia is the most serious risk, and it is in cases of diffuse suppurative cellulitis that this form of blood-poisoning assumes its most aggravated forms. The toxins of the streptococci are exceedingly virulent, and induce local death of tissue so rapidly that the protective emigration of leucocytes fails to take place. In some cases the passage of masses of free cocci in the lymphatics, or of infective emboli in the blood vessels, leads to the formation of pyogenic abscesses in vital organs, such as the brain, lungs, liver, kidneys, or other viscera. Hæmorrhage from erosion of arterial or venous trunks may take place and endanger life.
Treatment.—The treatment of diffuse cellulitis depends to a large extent on the situation and extent of the affected area, and on the stage of the process.
In the limbs, for example, where the application of a constricting band is practicable, Bier's method of inducing passive hyperæmia yields excellent results. If pus is formed, one or more small incisions are made and a light moist dressing placed over the wounds to absorb the discharge, but no drain is inserted. The whole of the inflamed area should be covered with gauze wrung out of a 1 in 10 solution of ichthyol in glycerine. The dressing is changed as often as necessary, and in the intervals when the band is off, gentle active and passive movements should be carried out to prevent the formation of adhesions. After incisions have been made, we have found the immersion of the limb, for a few hours at a time, in a water-bath containing warm boracic lotion or eusol a useful adjuvant to the passive hyperæmia.
Continuous irrigation of the part by a slow, steady stream of lotion, at the body temperature, such as eusol, or Dakin's solution, or boracic acid, or frequent washing with peroxide of hydrogen, has been found of value.
A suitably arranged splint adds to the comfort of the patient; and the limb should be placed in the attitude which, in the event of stiffness resulting, will least interfere with its usefulness. The elbow, for example, should be flexed to a little less than a right angle; at the wrist, the hand should be dorsiflexed and the fingers flexed slightly towards the palm.
Massage, passive movement, hot and cold douching, and other measures, may be necessary to get rid of the chronic œdema, adhesions of tendons, and stiffness of joints which sometimes remain.
In situations where a constricting band cannot be applied, for example, on the trunk or the neck, Klapp's suction bells may be used, small incisions being made to admit of the escape of pus.
If these measures fail or are impracticable, it may be necessary to make one or more free incisions, and to insert drainage-tubes, portions of rubber dam, or iodoform worsted.
The general treatment of toxæmia must be carried out, and in cases due to infection by streptococci, anti-streptococcic serum may be used.
In a few cases, amputation well above the seat of disease, by removing the source of toxin production, offers the only means of saving the patient.