COMEDO

Synonyms.—Blackhead; Fr., Comédon; Ger., Comedon; Mitesser.

Definition.—Comedo is a disorder of the sebaceous glands or
gland-ducts, characterized by yellowish or blackish, pin­point­ or pin-
head-sized puncta or elevations, corresponding to the gland orifices.

Symptoms.—Comedones are most usually observed on the face
only, upon which they may develop on all parts, but are frequently
in greatest number and sometimes solely to be seen about the angles
of the nose, the chin, especially near the mouth angles, and at the sides
of the temple, particularly toward the outer canthus. They are, how­
ever, often seen scattered irregularly over the face region, and may be
sparse in number or in great profusion. The back is also a not infre­
quent site, and in exceptional instances they have been observed upon
the penis (Lang). They appear to be yellowish, dirty gray, or black points
or dots. They may be on a level with the skin, or scarcely perceptibly
depressed or somewhat elevated (acne punctata). They are frequently
associated with oily seborrhea, the parts presenting a greasy or soiled
appearance. Even without the seborrheic association the blackheads,
if numerous, give the face a dingy or dirty aspect. Acne may also be
present, either to a slight or marked degree, but they are often observed
without a single associated inflammatory lesion. They vary somewhat
in size, generally larger near and on the nose and on the back; in the latter
region, when present at all, they are almost invariably large and numer­
ous. In such cases, too, the breast, and, in some instances, the abdomen
as well, show the formations. There is in the average case scarcely
perceptible elevation, unless the amount of retained secretion or accumu­
lation is excessive. Upon pressure this can be ejected, the small rounded
orifice through which it is expressed helping to give it a rounded, thread-
like shape—hence the names, “flesh­worms’’ and “grubs.” The so-called
double or multiple comedo, usually upon the back, and not at all infre-

COMEDO                                             1033

quent upon this region, to which Ohmann-Dumesnil¹ first directed atten­
tion, consists simply of somewhat closely contiguous blackheads, which
are beneath the surface intercommunicable, having a common glandular
chamber.

The course of comedo is chronic, the condition persisting indefinitely
or being somewhat variable; sometimes the plugs loosen and are dis­
lodged by the muscular motion of the part or by the act of washing.
In extremely rare instances slight atrophic scarring is observed to de­
velop at the follicular orifices (Lang, Neumann).² Not infrequently,
from some alteration in the imprisoned accumulation, either as a conse­
quence of pressure or possibly from a chemical change or an added micro-
bic factor, inflammation is excited, and a papular or pustular acne lesion
results.

Exceptionally comedones occur as distinct and usually symmetric,
densely crowded groups, more especially upon the forehead or the cheeks.
This peculiar variety or anomaly was first described by Thin,³ and sub­
sequently by Crocker⁴ and Wetherill;⁵ it is, however, extremely rare.
There is no tendency to suppuration, and the affection does not seem to
bear the relationship to acne that ordinary comedo does. Moreover,
they are usually smaller than the latter. Crocker states that dyspepsia
is the most common cause, and as “they occur chiefly on those parts
where flushing after meals is most marked," this latter is probably of some
etiologic influence.

Exceptionally, too, according to the observations of Crocker,⁶
Caesar,⁷ and Colcott Fox,⁸ somewhat densely crowded comedones occur
in very young children, usually on the forehead and occipital region,
against which the hat­band presses, and also on the cheeks in infants—
the part which comes in contact with the mother in nursing. On the
forehead, Colcott Fox states, the areas tend to join and form a continu­
ous band, scarcely a follicle escaping. It would appear that warmth and
moisture were partly etiologic, and, according to Crocker, Colcott Fox,
Haddon, and others, it sometimes develops simultaneously in several
of a family, and also in schools, suggesting a contagious or bacterial
factor. So far as I know no similar cases have been reported in this
country.

Etiology.—The contributory factors of comedo are essentially
those of acne—disorders of digestion, constipation, chlorosis, men­
strual irregularities, lack of tone in the muscular fibers of the skin, with,

¹ Ohmann-Dumesnil, Jour. Cutan. Dis., 1886, pp. 33 and 193, and Monatshefte,
1888, p. 57 (with 2 plates, containing 13 cuts), and St. Louis Med. and Surg. Jour.,
1888, Jan., Feb., March.

² Cited by Crocker, Diseases of the Skin.

³ Thin, “Grouped Comedones,” Lancet, 1888, ii, p. 712.

⁴ Crocker, “Symmetrically Grouped Comedones,” ibid., 1888, ii, p. 813.

⁵ Wetherill, “Symmetrically Grouped Comedones,” ibid., 1889, i, p. 169.

⁶ Crocker, Lancet, 1884, i, p. 704.

⁷ J. Caesar, ibid., 1884, i, p. 1188 (letter communication).

⁸ Colcott Fox, ibid., 1888, i, p. 665; Harries, Brit. Jour. Derm., 1911, p. 5, reports 4
cases of grouped comedones, in young children, aged six months, nine months, one and
one-half years, and three and one-half years (chiefly on the cheeks); suggests that
pressure and friction against the soiled garment of the mother might be of some import
in its production.

1034

DISEASES OF THE APPENDAGES

often, the infrequent use of soap and working in a dirty and dusty
atmosphere. Contact with tar oils and petroleum products are of im­
port in some instances. In some cases a predisposing constitutional
element seems entirely wanting. It is most common at the developing
age, from puberty up to thirty, when the cutaneous glandular structures
are most active. It is observed in both sexes, but more frequently,
according to my experience, in males. The microbacillus of Unna,
Hodara, and Sabouraud, referred to in acne, is looked upon by these
observers as of causative influence. The small parasite—demodex follic-

ulorum (acarus folliculorum) of Henle
and Simon—often found in the seba­
ceous mass is without etiologic signifi­
cance, as it is also found in healthy
follicles, although the same or a
similar organism is pathogenic in dogs
in provoking a follicular inflammation.
Pathology.—Pathologically the
initial step in the production of a
comedo is a blocking-up of the gland-
opening. Unna believes this to be
due to a thickening of the corneous
layer, both at the outlet and within
the duct; and that the microbacillus
may be the exciting factor. Kaposi
is inclined to believe that this in­
crease within the duct is due to the
irritation of the lanugo hair, which,
instead of finding egress at the orifice,
impinges against the opposite duct-
wall; he bases this view upon the
demonstration made by Biesiadecki
that this latter often happens, due
to the fact that the hair-follicle
often stands out almost at right
angles from the sebaceous gland-duct. It is possible, too, that a relaxed
condition of the arrectores pilorum muscles may also be instrumental
in their production by permitting the secretion to collect and harden.
The comedo plug is composed of epidermic cells and débris with seba­
ceous matter; this latter may accumulate to a considerable extent within
the gland, and from pressure cause atrophic destruction of the structure
(Bärensprung). To this pressure atrophy Ohmann-Dumesnil ascribes
the origin of the single glandular chamber with the multiple ducts
(multiple comedo), although Düring¹ believes that it is due to previous
destruction from suppurative acne lesions. The plug frequently con­
tains organisms other than those already named, but of no pathogenic
import, and occasionally one or more minute lanugo hairs. The outer
layer of the sebaceous mass is usually somewhat firm, composed of epi­
dermic horny material. According to Colcott Fox, in the peculiar com-
¹ Düring, Monatshefte, 1888, p. 401.

Fig. 257.—Comedo, showing dis-
tention of duct and slight glandular
disintegration (greatly magnified)
(courtesy of Dr. T. C. Gilchrist).

COMEDO

l035

edo eruption in children the plug is apparently formed from the epithelial
lining of the follicle and not from sebum. The dark point which or­
dinarily marks the comedo is probably in some instances due to accumu­
lation of dirt, but as it often occurs in those in whom this is scarcely pos­
sible, I am inclined to share Unna’s¹ opinion that it is due to pigment
(ultramarine) derived from the secretions. It is probable, too, that
exposure to air and light may have some influence in its production.

Diagnosis.—A condition so well known, and in which the pa­
tients usually make the diagnosis themselves, certainly offers no difficulty
in its recognition. It can scarcely be confounded with milium, as in this
latter there is no open outlet, no blackish point, and the contents cannot
be readily squeezed out, unless the lesions had been previously punc­
tured or incised.

Prognosis and Treatment—As a rule, with proper manage­
ment, the tendency to blackhead formation cannot only be materially
lessened, but removed. This presupposes, however, persistence and
cooperation on the patient’s part. It is true that some cases are obsti­
nate, and the ducts sometimes fill up again and again before success is
reached. The general management is practically the same as in acne,
the digestion and the condition of the bowels often needing attention,
and not infrequently in women advice as to proper regulation and treat­
ment of menstrual irregularities. The most useful and most frequently
prescribed remedies are cod-liver oil, in strumous and debilitated sub­
jects, and iron, arsenic, nux vomica, and other tonics; ergot is sometimes
useful in those cases in which there is lack of muscular tone. Hygienic
measures, such as general and local bathing, calisthenics, and open-air
life are of service. Upon the whole, the most commonly efficient general
treatment consists of laxatives and digestives, with supervision of the
dietary, general bathing, and sufficient exercise. In recent years favor­
able action has been reported from the use of acne bacillus vaccine.

The local treatment, which is also practically similar to that of acne
(q. v.), is of essential importance, and in some cases the sole measure
indicated. It has in view a removal of the sebaceous plugs and stimula­
tion of the glands and skin to healthy action. A procedure of value
consists in steaming nightly the parts for from five to fifteen minutes,
or the application of water as hot as can be comfortably borne; washing
with ordinary toilet-soap in some cases, and if the skin is not oversensitive,
with green soap or its tincture. The soap-washing should precede the
steaming or hot-water application. The application, two or three
times weekly, of a fairly strong faradic current—sufficiently strong to
produce slight muscular action—has been of material advantage in many
of my cases. The daily use of an exhaust cup,—cupping-glass not over
an inch opening,—going over the face thoroughly, is often of great service
not only as a measure of massage, but it tends to empty some follicles
and loosen the secretion in others. The plugs are also to be removed
by mechanical means—by lateral pressure with the finger-ends or by
means of a fenestrated curet-shaped or a watch-key-like instrument

¹ Unna, “Woraus besthet der schwarze Punkt der Comedonen?” Virchow’s Archiv,
1880, vol. lxxxii, p. 175; also Unna’s Histopathology.

1036                     DISEASES OF THE APPENDAGES

now to be had in the shops. Such removal may often be facilitated by
first insinuating a fine needle and gently loosening the plug from the em­
brace of the gland-duct. The ducts should be again emptied as soon as
they refill, which may occur several times. Just before the remedial
application, after the hot-water washing, etc, the parts should be dashed
with cold water. These adjunct and preliminary measures are to be
supplemented by remedial applications, which are essentially the same
as those employed in the treatment of acne. The sulphur preparations
are, upon the whole, the most useful, although exceptionally they seem
to aggravate the condition. Of the mercurials, corrosive sublimate is
the best, in the strength of from ½ to 3 grains (0.033-0.2) to the ounce
(32.) of water, applied nightly, and sometimes twice daily. When slight
roughness or bran-like scaliness supervenes or any irritation of the skin
arises, active remedial treatment is to be relaxed and soothing applica­
tions made for a few nights.

A paste-like application, warmly commended by Van Harlingen¹
as of special value in loosening the sebaceous plugs, is one consisting
of acetum, 3ij (8.); glycerin, 3iij (12); kaolin, 3iv (16.). This is spread
over the surface at night, the eyes being kept shut during its applica­
tion, owing to the pungency of the vinegar. For other applications
the reader is referred to the article on Acne, the best among which will
be found to be the lotion of zinc sulphate and potassium sulphuret, and
the stronger resorcin lotions and pastes.

Patulous ducts can often be made somewhat smaller by the electric
needle (electrolysis); also by a course (8 to 10) of mild to moderate ex­
posures to the x-ray.

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