Scoring for palmoplantar psoriasis – need for modification of current methodology

Psoriasis is a rather common inflammation of the skin, currently seen as a multi-system immune-mediated disorder. There are many variants, all can have significant clinical comorbidities which could be life altering.¹

Palmoplantar psoriasis affects the palms and soles, could occur alone or in conjunction with disease elsewhere, or with joint involvement. However, the mere presence of lesions on the palms and soles can significantly alter the health-related quality of life (HRQoL) of the patient. They are called high-impact sites. These patients report higher physical disability than other variants of plaque psoriasis without palmoplantar involvement. This makes it imperative to target treatment at these sites and have an accurate measure of disability, severity and response to treatment.

The acceptance and evaluation of any therapy needs to include the effect on these high-impact sites, the other high-impact sites are the face, genitals and flexures.

There are, at times, diagnostic confusions that arise when we talk about palmoplantar psoriasis, which needs to be diagnosed by biopsy or dermoscopy when isolated but is not an issue.²

The treatments need to be assessed by parameters to evaluate efficacy. In the past, these methods entailed the use of Palmoplantar PASI (PPPASI). This is a relatively staid measurement of the area of involvement. In this issue of IJDVL, Nagendran et al. have attempted to validate the modified Palmoplantar Psoriasis Area and Severity Index (m-PPPASI) in patients affected by PPP and to categorise it based on Dermatology Life Quality Index (DLQI).³ However, frequent lesions on the palms and soles are complicated by pustulation, fissures and pain. These are not quantified in the standard scores like PPPASI.⁴ A drug can be accepted if there is good functional impact on the activities of daily life and an improvement in HRQoL of the patient. A mere decrease in the body area involved is not enough anymore. The presence of a single painful fissure limiting the use of the hand will negate any alleviating effect of a drug on PPPASI. The presence of pustulation in palmoplantar psoriasis is important as many patients are affected by it, and there is considerable work going on about palmoplantar pustular psoriasis and pustulation in palmoplantar psoriasis. The presence of pustulation can be yet another limiting factor in using the hands, newer drugs like spesolimumab are being evaluated for their ability to address this problem. The degree of inflammation and pathways involved in palmoplantar psoriasis can be at variance with plaque psoriasis elsewhere.⁵

When we treat palmoplantar psoriasis, we need to focus on these aspects, namely, extent, severity, relief from pain due to fissuring and pustulation. A score that can assess these variables will be useful in capturing the effect of our treatment. We need a modified PPPASI that captures this data set. A simple mPPPASI as discussed in this journal, will be clinically useful. We use drugs like methotrexate, retinoids, apremilast and sometimes topical steroids to treat this. None of them work uniformly. Biologics are being offered as a better option.⁶

Soon, we will define the impact of this variant of psoriasis. One concern is its ability to predict arthropathy and nail involvement. Therapy for palmoplantar psoriasis will have to address this, probably with the help of better biomarkers. Drugs specific for targeting this variant will be available as many patients present with an isolated palmoplantar psoriasis. This is significant for future targeted approaches.

The future approaches to treating psoriasis will be based on treating psoriasis holistically and using treatments that can improve comorbidities. Given that palmoplantar psoriasis has a higher degree of comorbidity, and a variant, palmoplantar pustulosis has a significantly high load on the system due to the severity of inflammation, the scoring of PPP has to consider changes like pustulation which have a direct bearing on the choice of therapy. There is some upcoming evidence to suggest that these variants are more common in skin colour, which has a bearing on Indian dermatologists treating them.

An accurate scoring is the order of the day.