Clinical and laboratory study Number oj hairfollicles in psoriatic lesions 
K E Y 
WORDS 
hair follicle, 
number, 
psoriatic 
lesions, 
glabrous 
skin 
Evaluation of the number of llair 
f ollicles in psoriatic lesions of 
glabrous skin 
J Miljkovič, M. Berčič, A. Basta-Juzbašic and J. Lipozenčic 
ABSTRACT 
lntroduction. In analyzing biopsies of psoriatic lesions the impression is produced that the number of 
hair follicles is decreased. In the literature no unequivocal data could be found to decide whether the 
number of hair follicles was decreased or this was rather an optic impression due to epidermal hyperplasia. 
The studies published on the so-called "psoriatic alopecia" are few and contradictory. 
Methods. In each of 30 patients two punch biopsies were done: the first from a psoriatic lesion and the 
second from clinically non-altered surrounding skin of the gluteal region. In 20 cases the biopsy specimens 
were of 4 mm diameter and in 1 O cases the diameter was 6 mm. The number of follicles was counted in 
five horizontal histologic slices at the level of the infundibular part of the follicle. The mean value per cm2 
was calculated according to the equation a = r2n. Student's t - test of p < 0.05 was used for statistical 
evaluation. 
Results. The mean value of the number of hair follicles from psoriatic lesions amounted to 32.37 follicles/ 
cm2, while in the clinically unaltered skin the analogue value was 32.96 follicles/cm2. The deviation was 
statistically not significant at the level of 0.05. 
There was no correlation between the number of hair follicles and patient's age or duration of the disease. 
Conclusion. The number of hair follicles in psoriatic lesions is not decreased compared to follicles in 
perilesional healthy skin. An inadequate impression may be caused by the acanthosis of the epidermis. 
Introduction 
In typical cases the clinical diagnosis of psoriasis is 
easy. Atypical forms of psoriasis, however, frequently 
seen in everyday work, represent a diagnostic problem. 
In such cases histopathologic investigation is of great 
help, as it usually shows a typical histologic picture. 
Sometimes it is difficult to make a precise diagnosis 
based on current criteria for histopathologic differen-
tiation (1 ,2). The most difficult is the diagnosis in cases 
of isolated psoriasis on the scalp as well as isolated 
psoriasis on the palms and soles (3,4,5). 
acta dermatovenerologica A.P.A. Vol 8, 99, No 1 ----------------------------- 13 
Number t)f hair follicles in psoriatic lesions 
By routine reading histopathologic slides the 
impression is produced that in psoriatic lesions the 
number of hair follicles is decreased as compared to 
the normal skin. In the literature few <lata can be found 
regarding alterations of hair follicles in psoriasis, and 
even those are contradictory. 
The aim of the present study was to establish 
possible differences in the number of hair follicles in 
psoriatic lesions compared to the clinically non-involved 
skin in the same patients. An eventual difference in the 
number of follicles could be helpful as a diagnostic 
criterion in histopathologic differentiation of atypical 
psoriatic cases. 
The histologic symptoms of psoriasis depend on the 
type and duration of the skin lesion, its localization as 
well as on the therapy prior to biopsy. 
The current criteria far histopathologic differen-
tiation of psoriasis are: hyperkeratosis with para-
keratosis, regular acanthosis, reduction or total absence 
of the granular layer of epidermis, increased mitotic 
activity in keratinocytes of the basal layer, elongation 
of papillae containing dilated, tortuous capillaries and 
more or less dense infiltrations including lymphocytes, 
histiocytes, some mastocytes and in the early phase 
neutrophils, migration of neutrophils into the epidermis, 
deposits of neutrophils in parakeratotic areas of the 
corneal layer and Kogoj's spongiform pustules. 
Parakeratosis with or without deposits of neutr-
ophils, spongiform pustules and Munro's microa-
bscesses are the most significant criteria in histopatho-
logic differentiation of psoriasis (6) . Ali other criteria 
are nonspecific and may also be present in other 
inflammatory skin diseases. 
In making the differential diagnosis of psoriatic 
alterations on the scalp, severe forms of seborrhoic 
dermatitis are particularly relevant, as sometimes their 
histologic differentiation from psoriasis is practically 
impossible. 
A difficult problem is the differentiation of psoriasis 
on palms and so les where the histologic picture is rarely 
typical. Studies regarding this problem show that in 
clinically unclear cases a histologic investigation is 
helpful only in cases when the histologic symptoms are 
characteristic (7). 
Clinical and laboratory study 
Material and methods 
The study included 30 male patients with clinically 
evident psoriasis, aged 19-68 years. 
Ali patients had a generalized form of psoriasis and 
apart from local therapy ali of them had received sys-
temic PUVA treatment. No cytostatics were administered. 
No hair loss was noted in any of our patients, neither 
anamnestically nor clinically. 
In each patient two punch biopsies were carried out 
under local anesthesia with 2% xylocaine. The first 
biopsy was taken from a psoriatic lesion in the gluteal 
region and the second from surrounding clinically 
unaltered skin. 
Fram ali specimens paraffin histologic preparations, 
routinely stained with hemalum and eosin, were made. 
Ali specimens were investigated in horizontal sections 
made at the leve! of the infun<libular part of the follicles. 
In ali specimens the number of follicles was counte<l in 
five sections and calculated as the mean value per cm2 
according to the equation: a = r27t. 
In the fina! statistical analysis of data, obtained by 
counting the follicles in ali samples of clinically altered 
as well as unaltered skin, the t-test of p < 0.05 was used 
far statistical evaluation. 
The statistical analysis included the following <lata: 
the number offollicles/ cm2 in samples from the psoriatic 
lesion, the number of follicles/ cm2 in samples from 
clinically unaltered skin, the sum of ali corresponding 
values, the mean value, variability and SD. There is also 
a statistical presentation of the number of follicles with 
regard to the age of the patients and the dura ti on of the 
disease (Table 1). 
Results 
l.The values obtained show that there were no sta-
tisticaily significant differences in the number of follicles 
in psoriatic lesions as compared to the number of 
follicles in clinically unaltered skin of the same region. 
(Figures la,lb,2a,2b). 
The mean value of the number of follicles in sam ples 
from psoriatic lesions was 32.37/cm2, in samples from 
Table 1 . Presentation of statistically analysed data of altered and unaltered skin samples of patients. 
Age (years) 
Duration of disease (years) 
No. foll/cm2 (healthy skin) 
No. foll/cm2 (lesion) 
Difference 
14 
X :t SD 
49 ± 13 
12 ± 8 
32.96 ± 5.99 
32.37 ± 6.11 
0.59 ± 1.76 
Xmin 
19 
1 
23.88 
23.88 
- 3.19 
Xmax 
68 
30 
42.48 
42.48 
6.37 
acta dermatovenerologica A.P.A. Vol 8, 99, No 1 
Clinical a nd laborator y study 
Fig. 1 a. Horizontal section of involved skin 
sample (patient M.A.). Anatomically normal 
follicular units (HE 1 0x2). 
Fig. 1 b. Horizontal section of uninvolved skin 
sample (same patient). Anatomically normal 
follicular units (HE 1 0x2). 
acta dermatovenerologica A.P.A. Vo l 8, 99, No 1 
Number oj hair follicles in psoriatic lesions 
Fig. 2a. Horizontal section of involved skin 
sample (patient R.S.). Anatomically normal 
follicular units (HE 1 0x2). 
clinically unaltered skin 32.96/cm2 • The difference of 
0.59 ± 1.76 is not statistically significant as evidenced 
by the t -test p< O.OS (Table 1). 
2.There was no correlation between the number of 
follicles and the age of the patients and the duration of 
the disease. The coefficient of correlation with regard 
to age of patients was -0.1152; the coefficient regar-
ding the duration of the disease was -0.1485 (p< O.OS) 
(Table 1) . 
Fig. 2b. Horizontal section of uninvolved skin 
sample (same patient). Anatomically normal 
follicular units (HE 1 0x2). 
1.5 
Number 1!( hair .fiJ/licles in psoriatic lesions 
3. The impression of a decreased number of follicles in 
psoriatic lesions is due to hyperplasia of the epidermis. 
Discussion 
As already stated in the introduction, few data on 
hair follicle alterations in the skin of psoriatic patients 
can be founcl in the literature. 
In their electron microscopy stucly on changes in 
hair follicles of psoriatic patients, Wyatt et al. founcl in 
1972 that clystrophic alterations of hair follicles were 
more frequent in psoriatics than in the control group of 
healthy subjects (8) . Whether these dystrophic alte-
rations are connected with pathogenetic occurrences 
or whether they are the result of long-term therapeutic 
proceclures in psoriatics was not eluciclatecl. 
In a study on "psoriatic alopecia" in 1972, Shuster 
clifferentiates three types of hair loss: 
- Hair loss limited to the psoriatic lesion as the most 
frequent type of psoriatic scalp alopecia; 
- Acute hair loss in psoriatic lesions as well as in clinically 
unaltered skin of the scalp, characterizecl by an 
increased number of hair follicles in the telo gen pl1ase; 
- Alopecia with "follicular destruction" or cicatricial 
alopecia, a ve1y -rare form of psoriatic alopecia, which 
was also, verified histologically (9). 
Shuster's study does not exclucle the possibility that 
the telogen effluvium is perhaps merely a chance 
manifestation or the reaction to long-term therapy. 
Moreover, the results of the study are basecl only on 
clinical clata ancl on a small number of cases. 
In 1978, Verbov clescribecl a case of cicatricial scalp 
alopecia in a female psoriatic patient. Histologic inve-
stigation revealecl atrophy of the epiclermis, follicles ancl 
of sebaceous glancls as well as collagen sclerosis (10). 
Iclentical changes were also detectecl by Roclrigues 
et al. in 1983 (11). In 1985 Siemuncl clescribecl in cletail 
two cases with clestructive changes in the follicles in 
patients with scalp psoriasis. According to his opinion, 
the hair loss is the result of histologically confirmed 
inflammatoty changes in the clermis causing the destruc-
tion of follicles. The cause of these changes stili remains 
unknown (12). 
Diffuse alopecia is most common in erythroclermic 
fonns, but its appearance is also possible in the course 
of other forms of psoriasis. One of the causes of psoriatic 
alopecia is doubtlessly the routine removal of psoriatic 
scales (13). 
In their morphometric and histologic study of 28 
cases of scalp psoriasis Haedington et al. founcl that 
there was no significant difference between the number 
of follicles in psoriatic lesions as compared to clinically 
unalterecl skin ofthe scalp in the same patients (14). 
In 1989 Runne and Kroneisen published an ex-
16 
Clinical and laboratory study 
tensive study on 34 patients with psoriatic scalp alopecia. 
The course of hair loss was acute in 53% of patients, 
chronically recurrent in 15% ancl chronically progressive 
in 32%. In ali cases histologic investigation confirmecl 
the clinical cliagnosis of psoriasis. In some patients the 
histologic picture inclucled a perifollicular lymphocytic 
infiltrate, probably causing the subsequent clestruction 
of follicles. In the course of the clisease, intlammato1y 
processes of the foreign-bocly granuloma type cleve-
lopecl, causing cicatrization ancl thus clefinitive alopecia. 
After local therapy, complete regression of alopecia 
occurrecl in 70% of cases. On the basis of these clata the 
authors concludecl that psoriatic alopecia is the result 
ofthe basic disease, psoriasis , which responclecl well to 
local antipsoriatic therapy (15). 
In 1993 Runne et al. completecl their extensive stucly. 
On the basis of their results they believe that psoriatic 
alopecia doubtlessly exists as a special entity ancl that 
its occurrence is not so rare. The authors are of the 
opinion that the problem of psoriatic alopecia is a goocl 
example of how a false assumption can obstruct the 
acceptance of a scientific truth (16,17). 
In their histological investigation in 1990, Wright ancl 
Messinger confirmecl the intlammatory clestruction in 
the infunclibular part of the hair follicle in three patients 
with scalp psoriasis. Due to the similarity of histologic 
alterations in ali subjects, the authors believe that 
cicatricial alopecia may be a symptom of psoriasis, 
which observation is not to be generalized clue to the 
small number of patients uncler observation (18). 
In 1990 Orfanos believecl that the causes ofhair loss 
on the scalp of psoriatics were: 
- Alterations of the bulb with subsequent hair thinning 
and abnormal keratinization of the hair in psoriatic 
lesions; 
- Moclerate telogen effluvium in psoriatic skin; 
- Cicatricial alopecia which is rare ancl actually represents 
the result of secondary folliculitis ancl other traumatic 
agents in the course of the clisease (19) . 
Berth-Jones et al. attemptecl in 1990 to clarify the 
changes in the clynamics of the hair cycle causing so-
called "etretinate alopecia". This stucly includecl 22 
subjects treatecl in a period of 12 months. There were 
no marked alterations of anagen eft1uvit1m, but there 
was an increase in the number of hair in the telogen 
phase. Histologic investigation was not inclucled in this 
stucly (20). 
Degenerative changes in the hairs of two temale 
patients treated with etretinate were describecl by 
Shauder et al. in 1992. Their finclings suggest etretinate-
induced alteration of the expression of the psoriatic 
phenotype in the keratin composition ofhair in psoriatic 
patients (21). 
In 1995 Kretzschmar et al. established that perioclical 
hair loss as a result of psoriasis is a generally accepted 
acta dermatovenerologica A.P.A. Vol 8, 99, No 1 
Clinical a nd laboratory s tud y 
occurrence, but it has not been explained w hether 
psoriasis can cause alopecia. The authors described the 
case of a female patient with the typical clinical picture 
of psoriasis and cicatricial scalp alopecia. Histology 
revealed fibrous alterations at the site of previously 
existing follicles. As other possible causes for hair loss 
were excluded an etiopathogenetic connection between 
psoriasis and cicatricial alopecia was assumed. This is 
an extremely significant observation since prompt and 
appropriate treatment of psoriasis can prevent cicatricial 
alopecia (22). 
Conclusion 
The results of our study are in approximate corre-
spondence with the study by Haedington et al. , but we 
believe that the scalp is not an appropriate site for the 
histopathologic confirmation of scalp psoriasis. The 
diagnosis is extremely difficult, frequently even impo-
ssible, due to the similarity with other inflammatory scalp 
dermatoses (5). The dynamics of the scalp hair follicle 
differ from the dynamics of the follicle in other p a1ts of 
the body; it changes intensively with age and reacts 
differently to various stimuli (e.g. hormones). 
Therefore in our study we used skin samples from 
the gluteal region. 
The results obtained with the quantification of hair 
follicles in psoriatic lesions refuted our working 
hypothesis regarding the decreased number of follicles 
and showed that it is merely a visual impression caused 
by psoriasiform acanthosis present in psoriasis. 
In the course of our study and after examining the 
REFERENCES 
Number of hair follicles in psoriatic lesions 
available literature we became aware that the problem 
of the so-called "psoriatic alopecia" described by severa! 
authors, doubtlessly exists. Its cause is yet unknown. 
Whether alterations in follicle function are etiologically 
conditioned by psoriasis or whether they occur, as a 
result of long-term antipsoriatic therapy is a question, 
which remains to be answered. 
We believe that hair loss in psoriatic patients is a 
symptomatic occurrence due to: 
- Routine removal of scales from psoriatic lesions, either 
mechanically or medicamentously; 
- Long-term treatment w ith various local and systemic 
drugs; 
- Psoriasis is a chronic, recurrent inflammatory derma-
tosis. At any rate, chronic perifollicular inflammation, 
combined with the two above mentioned factors, is an 
important cause of degenerative changes in the follicles 
and of transitory or permanent hair loss in psoriatic 
lesions in the form of psoriatic alopecia. 
Data from the literature as well as our own obser-
vations serve to confirm that hair loss in psoriasis is 
reversible and can be prevented by prompt treatment. 
There is no evidence that a decrease in the number of 
follicles is the cause of hair loss. 
In the course of our study we observed no occu-
rrence of scars in the dermis. In most cases only a 
lymphohistiocytic infiltrate was present around the 
unaltered follicles. In all cases histologic symptoms 
characreristic for psoriasis were found. 
The results of our study did not clarify the cause of 
hair loss in psoriatic lesions with certainty. However, 
they can serve as useful data for further studies. 
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Number <if huirft,llicles in psoriatic lesions Clinical and laboratory study 
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A U T H O R S Jovan Miljkovič, MD, Department ojDermatology, Maribor Teaching 
A D D R E S S E S Hospital, Ljubljanska c., 6200 Maribor, Slovenia 
18 
Marija Berčič, MD, PhD, same address 
Aleksandra Basta-Juzbašič, MD, projessor oj dermatology, Department oj 
Dermatology, Clinical Center, Šalata 4, 1 O 000 Zagreb, Croatia 
Jasna Lipozenčič, MD, projessor and chairman, same address 
acta dermatovenero/ogica A.P.A. Vol 8, 99, No 1