Definition. A common disorder of the sebaceous function, characterized by small plugs of sebum which fill the gland-orifices.
Symptoms. Comedones are pin-point- to pin-head-sized, yellow, dark-green or blackish points, dots or papules, which may be elevated above, on a level with, or depressed beneath the surface of the skin. They may be easily pressed out of the ducts and if soft, a long, threadlike filament (skin worm) emerges, while if the sebaceous matter is firm and inspissated, oval, shiny, translucent bodies may be expressed. These fatty masses consist of sebum, epithelial and other debris and microorganisms, and are usually located upon the forehead, nose, chin, cheeks, neck, back and penis. They may be few or many, scattered or aggregated, but present no local subjective symptoms and pursue a chronic course with no effect upon the surrounding tissues. However, they are frequently associated with seborrhea and often, by mechanical, chemical or microbic irritation, give rise to acne. In children they have been observed on parts of the skin subject to heat and moisture, and here they are small and tend to become grouped. The double or multiple comedo, not unusual on the back, consists of closely grouped blackheads having a common glandular chamber.
Etiology and Pathology. Predisposing factors are those of acne, namely; gastrointestinal disorders, scrofula, chlorosis, menstrual irregularities and cachectic conditions. In a majority of cases blackheads are due to general or reflex influences arising from the disturbances mentioned. Comedones may appear at any age but they are commonest from puberty to the age of thirty while the glandular and pilary growth is most active. Comedones may be artificially produced in those who work constantly indust or dirt, as tar, coal and brass workers, or in those who do not use soap and water enough to keep the pores reasonably cleansed. I am inclined to believe that the sexes are affected equally.
Sabouraud, Unna and Hodara believe that the microbacillus found in all comedones is the real causal factor. The small parasite, demodex folliculorum, often found in sebaceous follicles and which produces a follicular inflammation in dogs, bears no etiological relation to the same condition in the human species, because it is also found in healthy follicles. The pathological findings of Unna are those usually accepted and embrace a thickening of the corneous layer with consequent duct closure, a similar change in the lining of the ducts, and the formation of the comedo from the sebum combining with the exfoliated scales. The dark point which marks the comedo is due to pigment (ultramarine) derived from the secretions, changed perhaps from exposure to the air and light, although fine particles of dirt may be the cause in specific instances.
Diagnosis. Gunpowder grains imbedded in the skin may resemble comedones but the impossibility of their removal by pressure, together with a history of the gunpowder accident, should be sufficient to differentiate. Milia have no open outlet, no black points, and their contents cannot be squeezed out except after incision or puncture. Frequent applications of pigments or medicated preparations of sulphur, mercury, tar, etc., may present an objective likeness to comedones, but careful examination and inquiry will clear the matter up. It should be remembered that comedones are associated with seborrhea and acne in varying degree.
Prognosis and Treatment. Comedones on the unexposed parts of the skin not subject to irritation need not be treated locally as they are apt to disappear spontaneously or from general treatment. When relief from the disfigurement is desired, especially in blackheads on the face, they may be removed in the following manner. The affected surface is sponged with glycerin and water or a lotion consisting of glycerin 1/2 ounce, rose water 2 ounces, oil of eucalyptus 15 drops. Then the comedo extractor, consisting of solid metal with an acne lance at one extremity and a curette at the other, in which an aperture has been cut on the reverse side and slightly trimmed out to fit around the point of the comedo, may be employed to remove the blemishes. While the number removed at one sitting is variable, depending upon their location, close proximity and sensitiveness of the skin, the procedure may be repeated once or twice weekly until all visible comedones are removed. A few will reform and other new ones will appear, necessitating a course of treatment extending over a few months’ time. The after treatment of the parts consists of bathing with hot water and the application of the above mentioned glycerin lotion.
It may prove beneficial to rub into the surface daily a non-medicated fat or oil, followed by nail brush friction with soap and water, if the extraction of the comedones is not attempted for any good reason. In obstinate cases, a thin paste made of kaolin 1 ounce, glycerin 6 drams, vinegar 1/2 ounce, may be used to loosen the plugs, or a lotion of precipitated sulphur 1/2 dram, glycerin and rose water each 1/2 ounce, milk of magnesia 3 ounces, may be employed as a stimulant. Occasionally, local massage by competent operators or with an electric vibrator, or a local application of the high-frequency currents may be used to improve the tone of the tissues. The immediate effects of the treatments will wear off in a few hours, so, if possible, they should be employed in the evening. Such physiological measures as are suggested for acne and seborrhea, together with the use of an internal remedy, often render local treatment, beyond mechanical cleanliness, unnecessary. The remedies usually indicated are among those mentioned for acne, especially Digitalis Juglans reg., Nit. acid, Pet., Sabina, Selenium, Sepia and Sulphur.