Pityriasis Alba versus Vitiligo Clinical and Histopathological Study

Background: Most recently there was a well established study showed that pityriasis alba of ten progresses into vitiligo (Sharquie et al.). These findings were considered a new thought that might support a new hypothesis regarding the pathogenesis of vitiligo. Objective: In order to do further work on hypothesis which is in favor that pityriasis alba might progress into vitiligo, so the present research including clinical and histopathological study to confirm that pityriasis alba might progress to vitiligo. Patients and method: This is a descriptive clinical and histopathological comparative study carried out in Department of Dermatology, Baghdad Teaching Hospital during the period from January 2015 to August 2016. Thirty eight patients with pityriasis alba (group A) and twenty eight patients with vitiligo stage I (group B) and twelve patients with both pityriasis alba and vitiligo (group C) were included in this study. All patients were fully interviewed and full history was taken from all the patients. Also careful asking about personal and family history of vitiligo was taken. Blunt trauma was done to induce Koebner’s phenomenon. Punch biopsies were taken from skin lesion of all patients and ten biopsies from 10 persons were taken from normal skin. Each biopsy specimen was processed and stained with Hematoxylin-eosin (H & E) and Fontana-Masson (FM) for histological evaluations. Results: Clinical study-Group A: Pityriasis alba patients: The mean of age of patients in pityriasis alba ± SD was 8.68 ± 5.94 years including 33 (86.84%) males and 5 (13.16%) females. Koebner’s phenomenon was positive in 2 (5.26%) patients and family history of vitiligo was positive in 17 (44.74%) patients. Group B: stage I vitiligo patients: The mean of age ± SD was 15.46 ± 12.50 years with 15 (57.14%) male patients and 12 (42.86%) female patients. A Koebner’s phenomenon was positive in 11 (39.28%) patients and family history of vitiligo was found in 11 (39.29%) patients. Group C: pityriasis alba and vitiligo patients: The mean of age ± SD


Introduction
Pityriasis alba (PA) is a common benign condition mainly affecting the head and neck regions of preadolescent children, more noticeable in darker skin types and there is no gender or skin type predilection [1] occurs predominantly in children between the ages of 3 and 16 years [2].The condition is more frequently seen in children and adolescents than in adults, it has been reported in 40% of Egyptian and 38.22% of Iraqi children [3], but is more common among males in Iraq [3].
The lesions are frequently limited to the face, but the neck, arms, and shoulders can also be affected [3].The etiology remains not well elucidated but pityriasis alba has been commonly characterized as a mild form of atopic dermatitis [1].
Excessive, unprotected sun exposure as well as hygienic habits (frequent bathing and hot baths) are strongly related to the development of pityriasis alba [1].All these conditions present as whitish scaly patches with ill-defined border (Sharquie personal communication 2013).Accordingly, we are facing a great challenge regarding distinction criteria of differentiation between pityriasis alba J. Cosmetics, Dermatological Sciences and Applications from early vitiligo or whether pityriasis alba progresses to vitiligo, or other post-inflammatory hypopigmentation.The criteria for distinction of pityriasis alba from early vitiligo include scaly lesion, indistinct margin, positive or negative wood's lamp and negative family history of vitiligo [4].
Accordingly we wonder whether pityriasis alba is clinical entity or part of manifestations of other inflammatory skin diseases, it could be part of atopic dermatitis and sometime psoriasis might present with pityriasis alba on face or could be part of dry skin or as manifestation of vitiligo [1].
In a recent study by Sharquie et al., 43.75% of the patients with pityriasis alba had progressed into ordinary vitiligo and this was confirmed by high positive family history of vitiligo, positive Koebner's phenomenon and complete absence of melanin by histopathological study [4].
Accordingly there is a high risk factor among patients with PA to change into vitiligo as both PA and vitiligo are inflammatory hypopigmented skin diseases [5] [6] [7].

Patients and Methods
A case descriptive, clinical and histopathological comparative study was carried out in the Department of Dermatology, Baghdad Teaching Hospital, Baghdad, Iraq, during the period from January 2015 to August 2016.
Thirty eight patients with pityriasis alba and twenty eight patients with stage I vitiligo and twelve patients with both pityriasis alba and vitiligo were included in this study.
All patients were fully interviewed and full history was taken from all the patients regarding the time of onset and the progression of the disease, and regarding pityriasis alba also asking about history of sun exposure and seasonal variation and history of excessive bathing and careful asking about family history of vitiligo.Physical examination was carried out regarding the clinical appearance of the patches, the site of the lesions, edges, size and the degree of pigmentation.This was confirmed by Wood's lamp to assess the degree of pigmentation (as confirmatory test).Blunt trauma to induce Koebner's phenomenon was done for all patients on the hidden area (back or upper arm) by blunt object, and watched after 1 week and after 1 month to see the appearance of leukoderma.
Punch biopsies were taken from skin lesion in the face or arms for all patients using sterilized stainless steel punch biopsy and ten biopsies from 10 person were taken from normal skin and processed similar to the patients biopsies.Each biopsy specimen was processed and stained with Hematoxylin-eosin (H & E) and Fontana-Masson (FM) stain was used for histochemical evaluations.Ensuring a formal consent of the parents of the patients and full explanation about the nature of disease, course, follow up and before taking photograph and biopsy and the ethical approval was obtained from the Scientific Council of Dermatology & Venereology-Iraqi Board for Medical Specializations.
Statistical comparison between two groups was performed using chi square test.

Results
Thirty eight patients with pityriasis alba (group A) and twenty eight patients with vitiligo (group B) and twelve patients with both pityriasis alba and vitiligo in the same patient (group C) were included in this study.

Group C (Combination of pityriasis alba and vitiligo patients)
Twelve patients were included in this study all of them had pityriasis alba and vitiligo in the same patient (Figure 3), with mean age ± SD was 8.33 ± 2.78 years including 9 (75%) males patients and 3 (25%) females patients.The duration of pityriasis alba was ranged from 2 weeks to 8 years, the patients less than 1 years were 3 (25%) and from 1 -5 years in 6 (50%) patients and more than 5 years in 3(25%) patients.While duration of vitiligo less than 1 year was in 9 (75%) patients while more than 1 year was in 3 (33.33%)patients.Vitiligo was active in 9 (75%) patients while Koebner's phenomenon was positive in 6 (50%) patients (Table 1).3).

Histopathological Study
The p-value estimated by chi square for comparison between three groups was showed that the p-value between group A (pityriasis alba) and group B (stage I vitiligo) in basal melanin in H & E stain was 0.540 and in Fontana stain was 0.692 mean there was no statistical significant deference between two groups (Table 4 and Table 5) while between pityriasis alba lesion and vitiligo lesion on group C in H & E stain was 0.345 and in Fontana stain was 0.407 and also there was no statistically significant difference (Table 6 and Table 7).

Discussion
Recently Sharquie et al. published as a study showed that pityriasis alba might progress into vitiligo during course of disease by the following observations: (43.75%) of patients showed progression of their original pityriasis alba lesion into vitiligo, also 34.35% of patients had positiveKoebner's phenomenon and 31.25% of patients had positive family of vitiligo [4].
So the target of present work is to confirm this hypothesis.Histopathology of stage I vitiligo had similarities with pityriasis alba as in stage I vitiligo, the rash of the disease appeared light brown hypopigmention in which there was partialpigment loss with inflammatory reaction.Epidermal mononuclear cell infiltration was seen in 80% of both the marginal areas and stage I vitiligo specimens [5].While Histopathology of pityriasis alba was Perivascular lymphocytic infiltrates and occasionally seen in the epidermisand Fontana-Masson staining showed that the amount of epidermal melanin was found to be significantly decreased in the epidermis of skinlesion when compared with perilesional normal skin [8].
While the present work had showed the following main findings: family history of vitiligo was positive in pityriasis albain 44.74%, stage I vitiligo was in 39.29% and in combination of pityriasis alba and vitiligo was 58.33% and this was in favor that both diseases were sharing common genetic element.While Koebner's phenomenon was positive in all 3 groups as seen in 5.26% of pityriasis alba and 39.28% in stage I vitiligo patients and in combination group was positive in 50% of patients.These findings strongly support the theory that vitiligo might start as pityriasis alba.
While the histopathology of the three groups showed inflammatory reaction in epidermis and dermis, melanin stores were reduced in the epidermis especially in the basal layered in all groups while melanophages were detected in dermis of patients with vitiligo and pityriasis alba.

Conclusion
The findings that are observed in present study are strongly in favor of the hypothesis that says pityriasis alba and vitiligo are sharing one genetic, clinical and histopathological pictures.As positive family history of vitiligo and high Koebner's phenomenon are seen in all three groups.Also there are many histopathological and histochemical similarities in these two diseases.

Figure 1 .
Figure 1.Fifteen years old male with severe Pityriasis alba lesion on the face for 2 years.

Figure 2 .
Figure 2. Fourteen years old male with Pityriasis alba for 8 months with positive Koebner's phenomenon.

Figure 3 .
Figure 3. Six years old male with history of Pityriasis alba for 3 years that progressed into vitiligo on same site after eighteen months.

Figure 4 .Figure 5 .
Figure 4. Normal skin from ten years old male and biopsy was taken from his arm (a) histopathology using H & S stain (×40) showed normal histology and (b) Fontana stain (×40) showed normal basal melanin.

Figure 6 .
Figure 6.Eight years old male with vitiligo for 3 years and biopsy was taken from trunk (a) histopathology H & E stain (10×) showed acanthosis, perivascular and periappendagealinflammatory infiltration and decrease in basal melanin; (b) Fontana stain (40×) showed reduction in basal melanin.

Table 1 .
Demographic data for all patients of three groups.

Table 3 .
The histopathological finding in group C (combination group pityriasis alba and vitiligo).

Table 4 .
Comparison of basal melanin in H & E stainbetween group A (pityriasis alba) & B (stage I vitiligo) according to compare with normalskin under microscope examination and using chi square to calculate p-value.

Table 5 .
Comparison of melanin in fontana stainbetween group A (pityriasis alba) & B (stage I vitiligo) according to compare with normal skin under microscope examination and using chi square to calculate p-value.

Table 6 .
Comparison of basal melanin in H & E stainbetween pityriasis alba lesion and vitiligo lesion in group C (combination group) according to compare with normal skin under microscope examinationand using chi square to calculate p-value.

Table 7 .
Comparison of basal melanin in fontana stainbetween pityriasis alba lesions and vitiligo lesions in group C (combination group) according to compare with normal skin under microscope examination and using chi square to calculate p-value.