A prospective study of two years was conducted from September 2015 to September 2017 at a tertiary care centre in the Department of Pathology. The ethical clearance was obtained and the number is INST.EC/EC/055/2015-2016. All patients who have been clinically diagnosed/suspected and untreated cases of psoriasis attending the Department of Dermatology were considered. A consent was taken by the dermatologists before performing biopsy in suspected cases. A wedge biopsy was taken under local anaesthesia. The tissue was immediately fixed in 10% formalin and processed for 24 hours in the tissue processor. The sections were cut to a thickness of 2-3 microns. The sections are brought to water and stained with harris hematoxylin for 2-3 minutes and washed in a running water. Counter staining done with aqueous eosin for 2 minutes and then dehydrated with absolute alcohol which was further followed by mounting the slide for histopathological analysis. Inclusion criteria were the cases suspected with features of psoriasis that is patients presenting with white scales, papules and plaques attending dermatology department. The other conditions micking similar clinical findings included seborrheic dermatitis, pityriasis rubra pilaris, allergic dermatitis, atopic dermatitis, nummular dermatitis, lichen simplex chronicus, pityriasis rosea, dermatophytosis, and mycosis fungoides were also considered. Exclusion criteria were cases those who were Immunocompromised, with infective etiology, patients who have taken treatment for psoriasis, Pregnancy and lactation.

In a study span of two years, 24 cases were diagnosed histopathologically as Psoriasis amongst which 17 (70.83%) cases were found to be in males and 7 (29.2%.) cases were to be in females with a mean age of 43 years. The most common clinical presentation was found to be erythematous plaque in 62.5% cases which was followed by hyperpigmented plaque in 41.6% cases, papules in 25%, scales in 24% cases and macule in 1% [Table/Fig-1,2]. The most common diagnostic histopathological feature in the present study was acanthosis, suprapapillary thinning, elongated rete ridges and parakeratosis. The other epidermal changes noted in our study were hyperkeratosis, Munroe microabscess, spongiosis, Hypogranulosis, melanocytes in the basal layer [Table/Fig-3,4,5 and 6]. Mitotic figures and parafollicular keratin plugging followed by basal vacuolar degeneration and exocytosis in few cases. The predominant dermal changes noted in our study in cases of psoriasis is lymphocytic aggregates varying from moderate to dense, followed by blood vessels in the papillary dermis and perivascular infiltration of lymphocytes, Papillary oedema and Perivascular infiltration of neutrophils. The percent distribution of the above mentioned findings is enlisted in [Table/Fig-7].

[Table/Fig-1,2]:

Violaceous plaques, papules seen in a case of psoriasis.

[Table/Fig-3]:

A case of psoriasis showing hyperkeratosis, acanthosis, spongiosis (H&E stain; 10 x).

[Table/Fig-4]:

A case of psoriasis showing elongated rete ridges, acanthosis, spongiosis, hypogranulosis (H&E stain; 40x).

[Table/Fig-5]:

A case of psoriasis munroe microabscess, parakeratosis, blood vessels in the papillary dermis (H&E Stain; 40x).

[Table/Fig-6]:

In the epidermis munroe microabscess, parakeratosis, hyperkeratosis, suprapapillary thinning. Papillary dermis with blood vessels and lymphocytes infiltrating around the blood vessels (H&E stain 10x).

When a correlation was drawn between histopathological and clinical diagnosis given by the dermatologist, 19 (79.16%) patients the histopathological findings confirmed the clinical diagnosis while in 5 cases (15.15%) it differed from the clinical diagnosis. The prognostic findings could not be assessed since the exclusion criteria in our study was patients who were on treatment for psoriasis.

An instant diagnosis can be arrived upon by virtue of visibility of the skin taking into account various visual clues such as scaling, colouring, arrangement and the site of distribution of lesions. Although this appears effortless, the pattern of recognition is complicated while factoring in the individual components and analysing them separately [8]. In the present study psoriasis was found more commonly in 41-50 years which was a consistent finding when compared with the study of Bell LM et al., [9]. Males were found most commonly affected, which was also found in the study of Younus M et al., [10]. A grading of histopathological findings of psoriasis on visual analogical scale was done by Moorchung N et al., [11] which included the parameters such as Hyperkeratosis which ranged from mild to marked, Presence or absence of Parakeratosis, Munroe microabscess, suprapillary thining, inflammatory infiltrate, capillary proliferation as in nil to marked. An association between various histopathological parameters was also done. In a similar manner in the current study the histopathological findings were graded in psoriatic patients and the results are as follows, 11 cases with mild hyperkeratosis, 4 with moderate and 2 cases with marked hyperkeratosis. Parakeratosis was present in 21 cases and munroe microabscess was present in 14 cases. Mild suprapapillary thinning was seen in 15 cases and moderate in 7 cases. Mild inflammation in 10 cases, moderate in 9 cases and marked in 5 cases. The association between different parameters was analysed by the likelihood ratio, and suprapapillary thinning carried a strong association with capillary dilation which was a consistent finding as seen in Moorchung N et al., [11]. Inflammatory infiltrate had a strong association with munroe microabscess which was not consistent with their study. Parakeratosis in our study had association with capillary dilation which was not favouring finding with their study.

Munroe microabscess was found to have a significant association with inflammatory infiltrate and capillary proliferation in our study which was a consistent finding. Capillary proliferation was found to have a strong association with suprapapillary thinning, parakeratosis and munroe microabscess which was not a consistent finding with Moorchung N et al., [11]. Thus from the above analysis we can note that capillary proliferation in the papillary dermis is most commonly found along with suprapapillary thinning, parakeratosis and munroe microabscess. In the present study, 84.8% histopathologically diagnosed cases of psoriasis was found concordant with the clinical diagnosis. When compared with other studies i.e., Reddy BR et al., and Chaudhary RG et al., [12,13]. Similarly the comparison of various histopathological findings found in our study with other studies was done which has been enlisted in [Table/Fig-8] [12,14-16]. Majority of the cases was concordant with their histopathological diagnosis, 94.11% and 74% respectively in their studies. The association between the various parameters presented in [Table/Fig-9].

The limitation found in our study was the less number of sample size diagnosed with psoriasis within a duration of two years. A still more strong association could have been obtained if the sample size was more. Also we obtained a few cases presenting with similar clinical findings as psoriasis but under histopathology not correlating with the features of psoriasis. Hence biopsy is highly recommended for the confirmation of diagnosis. This helps in appropriate management and for betterment of the patient.

Histopathological diagnosis forms the diagnostic tool for the dermatologists to arrive at a conclusion for their differential diagnosis since there are many disorders presenting with similar clinical features as psoriasis as mentioned earlier.