[Reprint from St. Louis Medical and Surgical Journal, August 
Hyphogenic, Coccogenic and Bacillogenic Sycosis. By Dr. 
P. G. Unna, Hamburg, Germany. 
There is scarcely a department in dermatology in which 
the great idea or principle of Parasitism has not operated 
toward advancement, enlightenment and (what was here so nec- 
essary) simplification. I say the principle of parasitism, be- 
cause the fructifying influences of the same reach far beyond 
the mere point where the chain of positive demonstration has 
thrown itself around some particular parasite and some defi- 
nite form of skin disease and linked them together. We ex- 
perience this progressive, educating influence in our daily 
clinical work, enabling us, it may be, to trace the etiology of 
forms of disease, hitherto considered identical, to differing 
parasitical causes, and thus to differentiate them ; or, it may 
be, to discover a common parasitical cause fora series of mani- 
festations and thus for the first time, make clear their re- 
lationship. 
This influence is felt, naturally enough, most strongly in 
those fields of dermatology wherein an exact demonstration 
of parasitism has already been made. And here I would call 
especial attention to the fact that we speak not merely of new 
(uninvestigated) skin diseases, but of those dermatoses as 
well, whose cause has for a long period been ascribed to mi- 
cro-organisms. For happily we are no longer so simple as to 
believe that in a skin disease having the clinical aspect of 
herpes tonsurans, for instance, we can by a microscopical ex- 
hibition of hyphen and spores make exact demonstration that 
a certain fungus, viz., tricophyton is the cause thereof. We 
have learned only too well that such absolute demonstration 
can be made only by isolation and inoculation of the fungus 
obtained by pure culture. Indeed, we are just now in condi- 
tion to say that we do not know that this particular fungus, 
tricophyton, is the cause of a simple disease (trichophytosis)1 
and that right here the work must be taken up at the begin- 
ning, exactly as with most other skin diseases. 
(1.) Note.—At present it is simply probable that the diseases known under the 
common name of herpes tonsurans and affecting the heads of children, the b°ard of 
adults, the bare skin, the nails, etc., owe their origin to closely related but not iden- 
tical causes. 
i i __ wimAiLmmmmm 2 
The subject of sycosis furnishes us a striking example on 
this very point. It sounds almost ridiculous in the light of 
our present knowledge, to hear the best authors of the past 
decade prating in sober earnest of a parasitic and non-parasitic 
sycosis ! True, Kobner, Barensprung and Hebra, Sr., ren- 
dered good service in their day when they raised the question 
of a difference between the ordinary folliculitis barbae, and the 
knotty form of sycosis harboring hyphomycetes. But here 
their progress stopped. For twenty long years (1867-1887) 
the simple, easy doctrine was taught that there is one form of 
sycosis which is caused by the common trichophyton and an- 
other by simple “inflammatory processes,” and, according to 
Wertheim, even mechanical disturbances of the beard follicles 
—the one as undemonstrated as the other improbable. 
A sudden termination to this highly unsatisfactory condi- 
tion of affairs came in 1887, when Bockhart2 succeeded in 
demonstrating that the ordinary pus cocci, under certain cir- 
cumstances, and among others by irruption into the hair folli- 
cles, could set up a sycosis of the skin, and that a sycosis so 
caused presented the typical phenomena of the disease known 
by this name. With a single blow the entire structure toppled 
over, and where, up to this period we had been compelled to 
resort to a flood of verbiage to conceal our ignorance concern- 
ing the ordinary sycosis, one sure fact, determined by exact 
demonstration, by pure culture and inoculation, made every- 
thing clear. Where, on the contrary, we thought that we 
knew something certain—that is in regard to trichophytosis of 
the beard—it became only too plain that,on account of the lack 
of this very experimentation by pure culture and inoculation, 
we were still a long ways from any exact knowledge. 
Coccogenic sycosis became suddenly one of the best under- 
stood of skin diseases, while the hyphogenic sycosis (for such 
we must provisionally call it) was relegated to the limbo of 
those diseases of the skin which the younger generation of 
dermatologists of to-day rightfully claim as belonging to their 
experimental domain. 
And already we have to register a third form of parasitic 
sycosis, whose discovery was made by means of pure culture 
and inoculation, and which therefore has reached the sure 
basis of exact experiment in advance of the only form of the 
disease formerly recognized as of parasitic origin (the hypho- 
genic). This differs from both the others in that it is bacillo- 
genic, and it was demonstrated in my laboratory, by Dr. Tom- 
masoli to be a distinct form of sycosis. But before I describe 
(2.) Monatshefte f. Prak. Derm. Dec. 1887, p. 45#. 3 
the clinical characteristics of this disease it is best that I bring 
to your attention somewhat more accurately the clinical dif- 
ferences existing between the only two forms of sycosis hither- 
to known. 
The starting point of hyphogenic sycosis (the so-called 
herpes tonsurans barbse) lies, as is well known, within the sub- 
stance of the hair itself. It is indeed, a peculiarity of the hy- 
phomycetes that they do not develop in liquids but upon the 
surface of the same, and that they thrive best upon moist solid 
substances. The hyphomycetes, therefore, which affect the 
skin are found in the horny layer of the epidermis ; in the hair 
they are found in the narrow clefts between the horny cells, 
above the border where the lymph circulates freely between 
the epithelium. 
The hyphomycetes which cause sycosis penetrate deeply 
into the hair follicle. The invasion of the hair papillae, the 
cutis and even the subcutaneous substance, is often maintained, 
but hitherto not supported with evidence. In consequence of 
this invasion the hairs become brittle. On attempted epila- 
tion they break either just above or just below the level of the 
skin. Epilation is painless but attended with meagre results. 
The staphylococci attack the hair bulb in a totally different 
manner. They thrive in the midst of the fluids of the textures, 
but an independent invasion of the horny substance is forbid- 
den them. The hair is therefore never the first seat, nor 
point of departure, of the disease, but rather the lymph space 
first, the fibrous coating next and finally the structural portion 
of the follicle. Pinkus has incidently called attention to the 
broad space between the hair and the root sheath as a road or 
path for invading cocci. Fortunately this space terminates, 
normally, as a blind pocket at the point were the root sheath 
is not completely cornified. When by traumatism or by me- 
chanical friction with material containing cocci, this cleft is 
stretched at the blind terminal in such a manner that some of 
the cocci get into the canal and there proliferate, the invasion 
of the follicle by cocci is rendered possible, and coccogenic 
sycosis makes a beginning. 
It is late before the hair substance is altered in this case 
and not until a considerable lapse of time after an oedema of 
the root sheath and the fibrous layer of the hair follicle has 
occurred. The hair never becomes brittle, but kinks up, and 
up to this latest stadium epilation of the sound hair is very 
painful, but results in the withdrawal of the shaft entire. 
As in the method of invasion, so throughout the further 
stages, the clinical characteristics of the two affections are 4 
radically different, especially in what concerns the immediate 
surroundings of the follicle. 
Hyphogenic sycosis exhibits large tubercles which reach 
down into the subcutaneous tissues and there become broad 
based. These are very soft, often quite fluctuating, and cause 
but little pain. They appear to be studded with the broken- 
off stumps of tricophytic hairs. 
Coccogenic sycosis also converts the hair follicles into tu- 
bercles, but these are small and firm, lie entirely within the 
cutis, are hard to the touch, hot, painful and usually crowned 
with a small postule. 
The intermediate interfollicular skin in hyphogenic sycosis 
is frequently not at all affected, especially in the onset of the 
disease. When, however, this occurs, the sycosis appears in 
the form of an epidermal desquamating eruption, with but 
little tendency to inflammation (displayed either as a deep 
redness around the edges or as a blister)—in short pityriasis, 
if you will, or psoriasis-like. 
Coccogenic sycosis may also leave the inner skin for along 
time intact, but in the course of time it is always involved, at 
least at those points where the follicles are very close togeth- 
er. The skin is strongly and diffusedly reddened, shining, 
tightly stretched, hot to the touch, and either free from des- 
quamation are but slightly affected in this direction. It 
quickly thickens and becomes swollen, by a strong infiltration 
of the entire cutis, into thick plates, which beneath the nos- 
trils become condylomatous pads. Here we have to deal with 
a true dermatitis—an inflammation of the entire cutis, resem- 
bling erysipelas. 
The same fundamental differences of the two forms of sy- 
cosis occur in their course from day to day. The hyphogenic 
folliculitis begins acutely and progresses ruthlessly from hair 
to hair. As the fungus invades the hair substance itself and 
is spread by the daily manipulations of combing, brushing, 
washing, etc.,—by handkerchiefs, napkins, pillows, but espec- 
ially by the finger nails, it finds no boundary save that of the 
beard itself, passing from the chin and cheeks to the mustache, 
but stopping at the hair of the head. It is for this reason 
that we say that while it is, very likely, closely allied to the 
trychophyton tonsurans which affects the scalp in childhood, it 
is not identical therewith (See Note, ante). Here also (in the 
trychophyton tonsurans of childhood), the infection from hair to 
hair is confined to a definite region within which, however, it 
progresses steadily, without a halt, and relatively rapidly. 
Altogether different is the case in coccogenic sycosis, where 
the march of infection is controlled not so much by the nature 5 
of the capillary substance itself as by the nature and method 
of its insertion in the body, and by external auxiliaries. Like 
the last mentioned, the progress of coccogenicbeard areas var- 
ies within the widest limits. In cases where the infection pro- 
ceeds by means of pus cocci from the nose as a starting point, 
it may be confined for months, or even years, to the portion of 
the upper lip directly under the nose, which is kept excoria- 
ted by wiping the latter with the handkerchief. In the same 
manner infiltrated, pustule-covered areas may remain station- 
ary for a very long time, upon the chin and cheeks, when cir- 
cumstances are not favorable for the spread of the infection. 
Generally, however, the manipulations which have been 
mentioned, and still more, an insufficient salve therapeusis, 
serve to slowly but surely spread the coccogenic sycosis over 
the hairy skin. For if the medicaments wThich are used have 
no power to destroy the cocci, the rubbing serves to infect the 
follicles with certainty. This then in no manner stops at the 
boundary of the beard but often rises above this sufficiently to 
gt t in front of the ears up to the hair of the head. I remem- 
ber seeing some extraordinary cases of this sort, in which the 
entire hairy scalp was affected by a coccogenic sycosis. 
In other cases a single manipulation may have the same 
result; for instance, shaving with a dull razor on a skin in- 
fected but superficially, may at one stroke infect a large num- 
ber of follicles and immediately cause an acute attack of coc- 
cogenic sycosis: The spread is generally slow, irregular, 
progressive, but not limited to any particular region, the 
course on this account being eminently chronic. 
So the spread of both diseases from case to case stands in 
most intimate connection with the aforementioned and shows 
the typical difference. The hyphomycetes of hyphogenic syco- 
sis requires only a single infection, in order to affect the whole 
beard rapidly; it is not in its nature endemic. On this ac- 
count we find by careful observation that this form of sycosis 
occurs in small epidemics spread from some barber shop. 
Such was an epidemic I observed in 1882, among the employes 
of a street car line, and which had spread from one barber 
shop. Since that time hyphogenic sycosis has shown itself 
much more common here as it has in Leipzig and Berlin, 
alth >ugh not observed as frequently as in Paris. 
Contrary to this, coccogenic sycosis is everywhere endemic. 
F«>] the originators of this form are present every where,being 
ihe universal pus-cocci. It is not necessary that clinically 
.-in.ii.tr cases be present to call this trouble into being. A fur- 
un ■ t>, a simple impetigo, a phlegmon, any suppuration, even 
tin di .t under a nail which has been used for scratching is 6 
sufficient, under some circumstances, to give rise to a cocco- 
genic sycosis which will last for years. Especially is the pus- 
cocci-laden dust dangerous, as it becomes attached to the 
vibrissse of the nostrils, remaining there and facilitating the 
entrance of the cocci into the follicles of the mustache when 
blowing the nose, being rubbed in as it were. The limitation 
of the occurrence of coccogenic sycosis therefore does not de- 
pend, as in the hyphogenic, in the limited occurrence of the 
parasites but in the necessity of favorable opportunities for 
its implantation. 
So too, the course of both diseases is, in typical cases, the 
widest and most different. Nothing is easier than to cure a 
fresh case of hyphogenic sycosis, which is, by the by, also in 
sharp contrast to the herpes tonsurans of the scalp of children. 
For our parasticides not only attack directly the point of origin 
of the disease—the hairs—but the causative hyphomycetes 
is killed by the simplest and weakest agents of this class. Even 
after the formation of considerable tubercles, the treatment of 
the affection is a relatively simple and even pleasant task. 
In contrast to this, the final and rapid healing of a coccogenic 
sycosis is one of the most difficult problems within our know- 
ledge. Nevertheless it is in this that is to be noted a marked 
advance, for which practice once again has to acknowledge 
thanks to theory which precedes it. Since we have learned sim- 
ple epilation does not reach the deeper and more powerful dis- 
ease masses in the lymph spaces of the noncorneous epithelia 
and of the hair bulb; that by this means we only produce a 
means of entrance for a more extensive infection, that further 
rubbing and kneading with infected ointments can only give 
rise to a new eruption and must necessarily do so, the thera- 
peusis by exclusion has become much more rational and more 
rapidly effective. 
That a cure may take place without any disfiguring bald 
spots or scars is also a matter which concerns therapeusis en- 
tirely. A hyphogenic sycosis should be cured without leaving 
any visible traces; for the suppuration and with it that of the 
hair-bulbs do not belong clinically to the pure form. 
In coccogenic sycosis, on the contrary, if left to itself the 
necessary result is to observe here and there the total suppura- 
tion of the follicle with the formation of scars. Nevertheless, 
a pustular affection of the upper hall of the hair-bulb, may ex- 
ist for a longtime without the appearance of the above results. 
However, should the lower part of the hair-bulb be transformed 
into a pus-sac, the prickle layer being broken up and destroyed, 
the bulb will be filled with connective tissue scars. To obvi- 7 
ate this final result is one of the particular objects of treat 
ment. 
But because this final result is dependent upon the recog- 
nition of the suppuration, I wish to say here a few words on 
this last as it is a very important point in the differential 
diagnosis. 
So far I have only compared the pure cases of both diseases. 
But it must not be forgotton that in old cases, the sharp boun- 
daries of both dermatoses may be somewhat obliterated, be- 
cause after the long continuance of hyphogenic sycosis the 
coccogenic form is generally added to it. Indeed considering 
the ubiquity of pus-cocci, it would be remarkable did such a 
thing not occur. For through the destruction of many hairs 
by the hyphomycetes there are affected so many points of 
entrance for the cocci. Through the avenues, opened by the 
hyphomycetes, the cocci are enabled to penetrate into the sub- 
cutaneous tissues more rapidly, and in addition, cause exten- 
sive phlegmonous processes such are not met with in purely 
coccogenic sycosis. Indeed, the broader and up to the present 
unsolved, if not difficult, question presents itself, whether the 
tubercles of hyphogenic sycosis are not indebted for their ex- 
istence to the infiltration of some cocci following the hypho- 
mycetes, or if this strong inflammatory oedema is caused by 
the presence of the latter alone. In a word, it is a question 
whether these tubercles are due to a mixed infection or not. 
But the occurrence of this mixed infection disturbs but very 
little the visible contrast, from all pathological points, between 
hyphogenic and coccogenic sycosis. 
What is the relationship to these two opposite conditions, 
of the third, new, bacillogenic form ? Of course the necessary 
a priori impression immediately suggests itself that this form is 
intimately connected with the coccogenic and equally remote 
to the hyphogenic. 
In a case of sycosis at my clinic, which clinically presented 
the appearance of a mild coccogenic sycosis, Tommasoli ob- 
tained at the commencement of the disease,a culture of bacilli 
with no trace of an admixture of pus-cocci. The bacilli were 
short rods, somewhat thick, with rounded ends, elliptical in 
form. They do not liquefy gelatin ; upon inoculating it with 
a needle, yellowish white, nail cultures with a smooth head 
are formed. They grow most rapidly and characteristically 
upon potatoes as a thick, yellow, mucoid growth,which spreads 
a very unpleasant odor, and around which the potato assumes 
a dark green color. Morphologically this bacillus ranks next 
to the B. parvus ovatus (Hoffler and to the B. pyogenes 
fcetidus, Passet. It is distinguished from the former by its 8 
inocuousness to rabbits, from the latter by the whitish yellow 
color it assumes in potato cultures. On this account I have, 
in conjunction with Tommasoli in particular, called it Bacillus 
sycosiferus foetidus).8 
By inoculating pure cultures upon the skin of rabbits and 
upon his own skin, Tommasoli obtained typical sycosis. In 
the latter he obtained the same picture as that presented by 
the original disease which furnished the material. There ap- 
peared red, indurated papules at the sites of the hair-bulbs, 
which carried at their apices small pustules. The intervening 
integument was red, the touching of the papules being painful; 
still more so in epilation, which brought forth apparently 
healthy hairs. Placed upon plates, the latter gave pure cul- 
tures of the Bacillus sycosiferus foetidus, although the contents 
were the minimum of pus accumulation whether of bacilli or 
of pus-cocci. The latter were found in the pus of pustules 
which appeared during the treatment, and obviously trans- 
formed a pure case to one of mixed infection. 
As the bacilli as well as the cocci are incapable of invading 
the horny layer, they can only call a sycosis into being by way 
of the hair-bulb. After the marked case in my clinic, and that 
produced by experimental inoculation on himself by Tommas- 
oli, it was seen that the symptoms of bacillogenic sycosis are 
very similar to those of a light coccogenic. The tubercular 
folliculitis attacks chiefly the upper portion of the hair-bulb; 
it suppurates but sparingly in the follicle of the hair-bulb; the 
inter-follicular coat shows a strong erythema, but less swell- 
ing and infiltration than in the coccogenic form; the course is 
chronic and apparently dependent upon further conditions of 
infection. It does not lead to suppuration attended by scar- 
ring. Besides this, bacillogenous sycosis is much less fre- 
quent than coccogenous. But it is very possible that, in a 
short time, we may find a much more frequent occurrence 
than we have heretofore observed. 
To me at least it appears that some of the cases of what 
has heretofore been looked upon as mild cases of coccogenic 
sycosis are really bacillogenic, so far as can be determined 
from the mild clinical appearance, especially in the case of 
mild interfollicular disease with a small amount of suppuration. 
The rapid development, even revolution in the study of 
sycosis, which we have observed during the few past years, is 
a beautiful illustration of the value of a systematic experimen- 
tal science, which has released itself from the bondage of the 
dogmas of Hebra’s catechism. 
(8). Further details upon this subject may be obtained from the following: Ueber 
bacillogene Sykosis,von Dr. P. Tommasoli: Monatshefte f. Prak. Dermat. 1889, 
Heft 11.