Comedo (Synonyms: Blackheads; Flesh-worms.)
What is comedo?
Comedo is a disorder of the sebaceous glands, characterized by yellowish or blackish pin-point or pin-head-sized puncta or elevations corresponding to the gland-orifices.
At what age and upon what parts are comedones found?
Usually between fifteen and thirty, and upon the face and upper part of the trunk, where they may exist sparsely or in great numbers. They are occasionally associated with oily seborrhœa, the parts presenting a greasy or soiled appearance.
Exceptionally they occur as distinct, and usually symmetrical, groups upon the forehead or the cheeks. On the upper trunk so-called double and multiple comedo have been noted—the two, three, or even four closely-contiguous blackheads are, beneath the surface, intercommunicable, the dividing duct-walls having apparently disappeared by fusion.
Describe an individual lesion.
It is pin-point to pin-head in size, dark yellowish, and usually with a central blackish point (hence the name blackheads). There is scarcely perceptible elevation, unless the amount of retained secretion is excessive. Upon pressure this may be ejected, the small, rounded orifice through which it is expressed giving it a thread-like shape (hence the name flesh-worms).
What is the usual course of comedo?
Chronic. The lesions may persist indefinitely or the condition may be somewhat variable. In many instances, either as a result of pressure or in consequence of chemical change in the sebaceous plugs or of the addition of a microbic factor, inflammation is excited and acne results. The two conditions are, in fact, usually associated.
To what may comedo often be ascribed?
To disorders of digestion, constipation, chlorosis, menstrual disturbance, lack of tone in the muscular fibres of the skin, the infrequent use of soap, and working in a dirty or dusty atmosphere. A small parasite (demodex folliculorum, acarus folliculorum) is sometimes found in the sebaceous mass, but its presence is without etiological significance, as it is also found in healthy follicles. A microbacillus has been found by several observers, and credited with etiological influence.
What is the pathology of comedo?
The sebaceous ducts or glands, or both, become blocked up with retained secretion and epithelial cells. The dark points which usually mark the lesions are probably due to accumulation of dirt, but may, as some writers maintain, be due to the presence of pigment-granules resulting from chemical change in the sebaceous matter.
Is there any difficulty in the diagnosis of comedo?
No. It can scarcely be confounded with milium, as in this latter disease the lesion has no open outlet, no black point, and the contents cannot be squeezed out.
Give the prognosis of comedo.
The result of treatment is usually favorable, although the disease is often rebellious. Relapses are not uncommon.
How would you treat a case of comedo?
By systemic (if indicated) and local measures.
The constitutional treatment aims at correction or palliation of the predisposing conditions, and the external applications have in view a removal of the sebaceous plugs and stimulation of the glands and skin to healthy action.
Name the systemic remedies commonly employed.
Cod-liver oil, iron, quinine, arsenic, nux vomica and other tonics; ergot in those cases in which there is lack of muscular tone, salines and aperient pills in constipation. The digestion is to be looked after and the bowels kept regular; indigestible food of all kinds is to be interdicted. Hygienic measures, such as general and local bathing, local massage, calisthenics, and open-air exercise, are of service.
Describe the local treatment.
Steaming the face or prolonged applications of hot water; washing with ordinary toilet soap and hot water, or, in sluggish cases, using tincture of green soap (tinct. saponis viridis) instead of the toilet soap; removal of the sebaceous plugs by mechanical means, such as lateral pressure with the finger ends or perpendicular pressure with a watch-key with rounded edges, or with an instrument specially contrived for this purpose; and after these preliminary measures, which should be carried out every night, a stimulating sulphur ointment or lotion, such as employed in the treatment of acne (q. v.), is to be thoroughly applied. The following is valuable:—
℞ Zinci sulphatis,
Potassi sulphureti, ...................āā......... ʒj-ʒiv.
Alcoholi ........................................ f℥ss.
Aquæ, ........................... q.s. ad. ...... f℥iv. M.
Should slight scaliness or a mild degree of irritation of the skin be brought about, active external treatment is to be discontinued for a few days and soothing applications made. Resorcin, in lotion, 3 to 25 per cent strength, is through the exfoliation it provokes, frequently of value; the resorcin paste referred to in acne can also be used for this purpose.
Moderately strong applications of the Faradic current, repeated once or twice weekly, are sometimes of service; also weak to moderately strong applications of the continuous and high-frequency currents. Röntgen-ray treatment can also be resorted to in extremely obstinate cases.
In occasional instances sulphur preparations not only fail to do good, but materially aggravate the condition. In such cases, if resorcin preparations also fail, the mercurial lotion and ointment employed in acne may be prescribed. Mercurial and sulphur applications should not be used, it need scarcely be said, within a week or ten days of each other, otherwise an increase in the comedones and a slight darkening of the skin result from the formation of the black sulphuret of mercury.