|Year : 2015 | Volume
| Issue : 1 | Page : 43-47
Morphometry analysis of psoriasis and psoriasiform dermatitis: A retrospective study of 50 cases
Shirish S Chanadanwale1, Narayanan K Panicker1, Sushmah P Kulkarni1, Komal R Shah1, Harsh Kumar1, Yugal K Sharma2, Sukanya Pal1
1 Department of Dermatology and Venerology and Leprology, Dr. D Y Patil Medical College, Hospital and Research Centre, Dr. D Y Patil Vidyapeeth, Pune, Maharashtra, India
2 Department of Pathology , Dr. D Y Patil Medical College, Hospital and Research Centre, Dr. D Y Patil Vidyapeeth, Pune, Maharashtra, India
|Date of Web Publication||8-Jan-2015|
Shirish S Chanadanwale
75/1+2/1 Krishna Apartments, New Sangiv, Pune - 411 027, Maharashtra
Source of Support: None, Conflict of Interest: None
Background: Clinical and histomorphological features of psoriasis and its close mimickers have many overlapping features. The diagnostic differentiation of psoriasis from other psoriasiform eruptions enables treatment as per the extent of eruptions and modified according to the tissues involved and associated co morbidities. Morphometric analysis of histopathological features may help to alleviate this dilemma. Aim: This study attempts to evaluate the morphometric measurements using eye-piece micrometer in differentiating psoriasis from psoriaform dermatitis. Materials and Methods: The 50 cases, 25 each of clinically and histologically confirmed cases of psoriasis and psoriasiform dermatitis were compared by using measurable morphometric parameters. The results were statistically analyzed for significance. Results: Length of rete pegs, length of dermal papillae and the ratio of length/average width of rete pegs showed statistically significant increase in psoriasis when compared to psoriaform dermatitis. Suprapapillary thickness had less significance. Some other important histomorphological parameters were also compared. Conclusion: The length of rete pegs, the length of dermal papillae and the ratio of length/average width of rete pegs are statistically more significant in the diagnosis of psoriasis when compared to psoriasiform dermatitis.
Keywords: Eye-piece micrometer, morphometry, psoriasiform dermatitis, psoriasis
|How to cite this article:|
Chanadanwale SS, Panicker NK, Kulkarni SP, Shah KR, Kumar H, Sharma YK, Pal S. Morphometry analysis of psoriasis and psoriasiform dermatitis: A retrospective study of 50 cases. Med J DY Patil Univ 2015;8:43-7
| Introduction|| |
Psoriasis is probably one of the longest known illnesses of humans and simultaneously one of the most misunderstood. Prevalence in different populations varies from 0% to 11.8%, respectively. Incidence is twice in males when compared to females and most patients are in their third and fourth decade at the time of presentation.  The diagnosis of psoriasis is usually made simply by the clinical appearances. Psoriasis has different clinical variants that mimic diverse dermatological conditions. Besides, clinical features in one patient may differ at different times and sometimes, the diagnosis may get obscured, as in cases of erythroderma. These patients often prove to be a diagnostic dilemma for the clinician and warrant a histopathological confirmation. Histologically, psoriasis vulgaris must be differentiated from psoriasiform dermatitis, which refers to a group of disorders which clinically and or histologically simulates psoriasis. ,, In standard textbooks, dilated blood vessels in dermal papillae, regular epidermal hyperplasia, and presence of Munro micro abscess and/or Kogoj's abscess have been described to be the most constant or characteristic histopathological features in skin biopsy of psoriasis. ,, However, the frequency with which an individual feature or a combination of features is seen in clinically diagnosed cases, has not been studied extensively. Histopathology can, at the best quantify the grade of epidermal thickness as mild, moderate or severe. Morphometry analysis uses special software (Dewinter Optical Inc with Digi Eye 330 digital photomicrography camera and Biowizard 4.2 image analysis software) which gives a quantitative dimension to histopathology. Few studies of morphometry analysis by using special software have been done in the past for quantitative measurements of some of the histological parameters in psoriasis. ,,,, To the best of our knowledge, no study has been done in the past for measuring histological parameters of psoriasis and psoriasiform dermatitis quantitatively using eye-piece micrometer in the light microscope without using special software.
The aim of this study was to quantify the parameters of diagnostic significance by using eye-piece micrometer with the light microscope without using special software and to evaluate their significance statistically in diagnosis of psoriasis and in differentiating psoriasis from psoriasiform dermatitis.
| Materials and Methods|| |
Skin biopsies of 50 cases were included in the study over the duration of 2 years (July 2011 to August 2013). Half of these were clinically diagnosed and confirmed histologically as psoriasis and the remaining 25 cases were of psoriasiform dermatitis. The study was evaluated and approved by the Institute Ethical Committee. Relevant clinical data and opinion of the dermatologist were recorded. The exclusion criteria included biopsies, which were provided with insufficient clinical data, small having <5 well defined rete pegs and those with distorted orientation.
A stage micrometer was used to calibrate the eye-piece micrometer. The stage micrometer used in this study had 1 mm divided into 100 divisions, each division corresponding to 10 μm. After the eye-piece reticle has been calibrated with the stage micrometer, micro sections linear dimensions can be measured [Figure 1]. To increase accuracy, measurements were taken at four well defined areas of the lesion seen in the microscopic field and the average was taken.
Hematoxylin and eosin stained 3-4 micron thick sections were used for the micrometric measurements. The length of the rete pegs, length of dermal papillae, supra papillary thickness, length over average width of the rete pegs, ratio of width at 25% length over 75% length of rete pegs were measured using ocular micrometer [Figure 2]. The distance from the upper part of the granular layer to the bottom of the epidermis was measured as rete peg length. Next, the lengths of the dermal papillae were measured from the tip of dermal papillae to the base at the level of tip of rete pegs. Supra papillary thickness was measured from the tip of dermal papillae to the top of the granular layer. The ratio of length to average width of rete pegs was calculated by dividing the length of papillae by average width. This was followed by taking the ratio of measurements at upper narrowest and lower widest part of rete pegs, which corresponded approximately to about 25% and 75% of the length of rete pegs, respectively. The measurements were made in a ×100 field for all the parameters. The granular layer thickness was assessed by counting the number of granular cells vertically in supra papillary areas and at the base of rete pegs in four areas in the biopsy and taking the average. The predominant types of inflammatory cells in dermis were noted. For each biopsy specimen, four different areas representing the lesion for each parameter were measured and the average was calculated.
|Figure 2: Morphometric measurements: Yellow arrow-length of the rete pegs, blue arrow-length of dermal papillae, brown arrow-supra papillary epidermal thickness, green and red arrow respectively-width of rete pegs at upper narrowest and lower widest part (H and E, ×400)|
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All the morphometric parameters were statistically analyzed for each sample. The mean values of these parameters with a standard deviation (SD) were calculated separately for psoriasis and psoriasiform dermatitis. Data were reported as mean, SD and range of these parameters. The statistical correlations of the epidermal parameters of psoriasis and psoriasis-like lesions were calculated using Student's t-test and the t value and P value were calculated. The distributions of the samples according to the evaluated parameters were also studied. Statistical analysis was done using Primer of Biostats (Software provided with Glantz S A. Primer of Biostatistics, 7 th Edition, New York, McGraw Hill Medical 2012).
| Results|| |
Histopathology slides were examined independently by two pathologists. High concordance rate was noted between the both pathologists. Of 25 cases of psoriasiform dermatitis most common (n = 9) lesion was pityriasis rosea followed by psoriasiform hyperplasia (n = 7), lichen simplex chronicus (n = 3), pityriasis rubra pilaris and parapsoriasis (n = 2) each, and exfoliative dermatitis and inflammatory linear verrucous epidermal nevus one each. Acanthosis, hyperkeratosis, parakeratosis, dilated tortuous blood vessels in dermis were seen in all cases of psoriasis. In psoriasiform dermatitis, commonest histological feature was hyperkeratosis (68%) followed by acanthosis and parakeratosis each in 60% cases.
[Table 1] shows detailed frequency of important histological features in psoriasis and psoriasiform dermatitis. [Table 2] shows maximum, minimum and mean values of histological parameters in psoriasis and psoriasiform dermatitis number of granular cell layers were less in psoriasis when compared to psoriasis dermatitis. Lymphocytes were the predominant inflammatory cells in psoriasiform dermatitis, while psoriasis showed neutrophils and lymphocytes. [Table 3] shows the morphometry analysis of histological features of psoriasis and psoriasiform dermatitis with a mean deviation and statistical significance.
| Discussion|| |
Psoriasis is a chronic inflammatory autoimmune disease, potentially affecting all areas of skin and nails with various systemic associations.  The disease requires long and relatively expensive treatment and criteria are needed to contribute to its diagnosis and to estimate periods of remission and exacerbation. The clinical relevance of the findings must be clear and reliable. With digitization and the development of computer aided diagnosis, histopathological image analysis has attracted a considerable interest in recent years.
We studied histological features of 50 skin biopsies. Of the 50 biopsies, 25 each were psoriasis and psoriasiform dermatitis. The age groups of the patients varied between 17 and 75 years of age. Patients of psoriasis were younger than psoriasiform dermatitis. Bedi analyzed 530 cases of psoriasis and found that more than half the patients of psoriasis were in their third to fourth decade.  Extremities were the most common biopsy site in our study while Bedi found that the scalp and the extremities were the most common sites of involvement and a large majority (74%) showed nail changes of one type or other whereas nail involvement was seen only in two cases in our study.
Males were commonly affected than females in both psoriasis and psoriasiform dermatitis. Similar observations were made by Icen et al. 
Among the histological features acanthosis, parakeratosis, hyperkeratosis, dilated blood vessels and inflammatory infiltrate in the upper dermis were seen in 100% (n = 25) of psoriasis cases. Acanthosis (P = 0.001), hyperkeratosis (P = 0.003), parakeratosis (P = 0.001), Munro micro abscess (P = 0.0001), dilated dermal blood vessels (P = 0.0001) were statistically significant in psoriasis when compared to psoriasis-like lesions. Among them the presence of Munro micro abscess was highly significant (P = 0.0001).
Among the morphometry parameters following results and statistical values were obtained. The length of rete pegs (t = 4.036 with 48 degrees of freedom; P = 0.0001), supra papillary thickness (t = −1.543 with 48 degrees of freedom; P = 0.129), length of dermal papillae (t = 273.144 with 48 degrees of freedom; P = 0.0001), length/average width of rete pegs (t = 23.856 with 48 degrees of freedom; P = 0.0001), ratio of widths of rete pegs (t = −0.022 with 48 degrees of freedom; P = 0.983).
The mean length of rete pegs in psoriasis cases was 356.2 μm with SD of 168.9, where as in psoriasiform dermatitis it was 203.7 μm with SD of 78.47. The mean length of rete pegs was 1.74 times greater in psoriasis when compared to psoriasiform dermatitis. The significant average difference in length of rete pegs was 152.5 μm. Alper et al.  found that the length of rete pegs was 2.74 times greater in psoriatic skin when compared to normal controls (t = 12.95 and P = 0.0001). The difference in length of rete pegs in our study was significant with t = 4.036 and P = 0.0001.
The mean length of dermal papillae was 299.06 μm in psoriasis, while in psoriasiform dermatitis it was 157.78 μm. The difference in the length was 141.3 μm, which was found to be significant. The dermal papillae of psoriatic skin were 1.89 times longer than psoriasiform dermatitis. This difference was statistically significant with t = 273.144 and P = 0.0001. The length of dermal papillae and rete pegs are complementary to each other.
The mean supra papillary thickness of epidermis overlying the dermal papillae of psoriatic skin was 53.75 μm and that of psoriasiform dermatitis was 70.83 μm. The mean difference in thickness was found to be 17.08 μm less in psoriasis. This mean difference was statistically insignificant with t = 1.543 and P = 0.129. Similar result was obtained by Alper  with similar supra papillary thickness in cases and controls (t = 0.67 and P = 0.503). Thus, the supra papillary epidermal thickness has low significance in the diagnosis of psoriasis as compared to normal controls.
The ratio of average length and width of rete pegs was considered representative of shape of rete pegs. If the ratio is greater, the rete pegs are narrower. The mean of this ratio was found to be 5.44 in case of psoriasis and 3.62 in psoriasiform dermatitis. The difference in the ratio, which was considered significant was 1.82. This was statistically significant with t = 23.856 and P = 0.0001. Alper et al. in their study found that the dermal papillae were 13% narrower in psoriatic patients when compared to controls. He did not measure the rete pegs and hence the figures cannot be compared. The higher ratio of length over average width of rete pegs confirms the histopathological finding of slender long rete pegs, which favors the diagnosis of psoriasis.
The ratio of width of rete pegs at 25% of length to that at 75% of length was calculated. Lower the ratio, more it favors the histopathological feature of "club shaped rete pegs." The mean of this ratio in case of psoriasis was 0.55 and that of psoriasiform dermatitis was 1.3. This difference in ratio was statistically insignificant with t = 0.002 and P = 0.983. Thus the morphometry measurements taken to determine the club shape rete pegs were found to be insignificant in our study.
Granular cell layer was absent in 32% (n = 8) cases of psoriasis. Remaining 68% (n = 17) cases showed <3 cell layer thick granular layer. Similar finding were reported in many studies. ,,, Whereas 92% (n = 23) cases of psoriasiform dermatitis showed granular cell layer of >3 cell layers thick. In remaining 8% (n = 2) cases, it was >2, but <3 cell layer thick. Thus, granular layer thickness <3 cell layer thick favored the diagnosis of psoriasis as compared to psoriasiform dermatitis.
Munro micro abscess and spongiform pustule of Kogoj were noted in 56% (n = 14) and 20% (n = 5) cases of psoriasis respectively, while they were absent in all psoriasiform dermatitis. Five cases of psoriasis had both Munro micro abscess and spongiform pustule of Kogoj. Gordon and Johnson,  Chopra et al.,  Puri et al.,  found Munro micro abscess to be of diagnostic significance, whereas De Rosa and Mignogna  stated that though Munro micro abscess and Kogoj micro pustules are diagnostic clues of psoriasis, they are not always present. Helwig found that Munro micro abscess are not found in early lesions of psoriasis. 
Inflammatory cells were noted in the dermis of all cases of psoriasis and psoriasiform dermatitis. We found that there was almost equal distribution of neutrophils, lymphocytes or mixture of both in psoriasis, whereas psoriasiform dermatitis lesions showed predominantly lymphocytes in 84% (n = 21) patients. Helwig,  Ragaz and Ackerman,  Ackerman et al.  and Tomasini et al.  in their studies found lymphocytes as predominant infiltrate in psoriatic biopsies, whereas Gordon and Johnson  and Chopra et al.  found neutrophils as predominant inflammatory cells in psoriasis.
The dermal papillae showed tortuous capillaries in all cases of psoriasis whereas 7 out of 25 cases of psoriasiform dermatitis showed few tortuous capillaries in the upper dermis, mostly in pityriasis rosea. Similar observations were noted by Gupta et al. 
| Conclusion|| |
The morphometry parameters such as length of rete pegs, the length of dermal papillae and the ratio of length/average width of rete pegs are statistically significant in the diagnosis of psoriasis as compared to psoriasiform dermatitis. The diagnostic differentiation of psoriasis from other psoriasiform eruptions enables treatment as per the extent of eruptions and modified according to the tissues involved and associated co morbidities. More studies are required to confirm our findings and substantiate these findings, it will assist in definitive diagnosis of psoriasis in skin biopsies.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]
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