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PSORIASIS occurs in many forms, but by far the most common type of psoriasis is the chronic plaque type( up to 90 % of presentations), also known as psoriasis vulgaris. For the sake of simplicity, the reference to psoriasis in this paper should be interpreted as chronic plaque type psoriasis.
Chronic plaque type psoriasis typically affects the extensor surfaces( see figures 1 and 2) such as the elbows and knees, and also the scalp. It is a very common condition, prevalent in up to 2-3 % of the adult population. 2, 4, 5 Though psoriasis can present at any age, the mean age of onset has a bimodal distribution at 15-20 years and 55-60 years. 4 It is equally distributed across the genders. 6
Subtypes of psoriasis include guttate, inverse, genital, pustular, nail, or joint psoriasis( see figure 1). Particular subtypes such as erythrodermic or geographic psoriasis characterise psoriasis vulgaris affecting extensive body sites. Environmental triggers and genetic components are thought to be factors implicated in the development of the disease.
A higher incidence of psoriasis in those with a positive family history in a first- or second-degree relative, and high concordance rates in twin
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Nail matrix
Pitting
Leukonychia
Red spots in the lunula
Nail plate crumbling / dystrophy
studies, helps in pointing toward a genetic basis. 2
Disease heterogeneity makes it difficult to explicitly define all genetic determinants, but more than seven major loci on various chromosomes have been identified. 4 Of note, human leucocyte antigen( HLA)-Cw6 has been identified as one major locus with a strong association with early onset, more severe, persistent, and guttatetype psoriasis. 2, 5 Identified triggers include trauma( for example, tattoos, abrasions, sunburn), systemic drugs( for example, beta blockers, lithium, NSAIDS), and infections. 2
In terms of infection, streptococcal infections in particular have an established role in triggering disease, whereas the role of most viruses and fungi is uncertain. 2
Interestingly, approximately half of those with psoriasis also have nail psoriasis( see figures 1 and 3, and table 1) at the time of diagnosis,
Table 1. Nail psoriasis signs
Nail bed
Subungual hyperkeratosis
Onycholysis
Splinter haemorrhages
Oil drop / salmon patch discolouration
and a high percentage( up to 90 %) of people with psoriatic arthritis exhibit nail psoriasis. 2, 5
Conversely, patients may present with an arthropathy that leads to a diagnosis of previously undetected or more subtle psoriasis.
But typically, skin lesions precede joint symptoms and are present on average 12 years prior to the onset of joint symptoms. Up to one-third of patients affected by psoriasis develop psoriatic arthritis. 6, 7
Some features in psoriasis patients that are good indicators of developing psoriatic arthritis include( but are not limited to) presence of severe psoriasis, a positive family history of psoriasis or psoriatic arthritis, history of musculoskeletal pain or fatigue, nail dystrophy, dactylitis, and the presence of scalp / intergluteal / perianal psoriasis. 7
Similarly, psoriasis is associated with important comorbidities that
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should be recognised, treated early, and monitored. These include, but are not limited to, cardiovascular disease, hypertension, diabetes, dyslipidaemia, obesity, certain malignancies, non-alcoholic fatty liver disease and Crohn’ s disease( in addition to its significant psychosocial associations). 1, 2, 8
The associations of oncological and cardiovascular risk in psoriasis are complex and likely to be multifactorial. Whether it is the treatment of psoriasis rather than psoriasis itself causing an increased incidence of malignancies such as skin cancers and lymphomas is an ongoing debateable issue. 1, 2
However, in terms of cardiovascular risk, recent literature including data from meta-analyses tend to indicate that cardiovascular risk and its associated mortality is higher in patients with psoriasis. 1, 2
Though the pathogenic link between psoriasis and its cardiovascular risk is not fully elucidated, there is some suggestion that the state of systemic inflammation found in psoriatic patients tends to drive cardiovascular disease possibly via the same mechanisms that induce insulin resistance. 1, 2 This increased risk is appreciated more often in patients with severe rather
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than mild psoriasis. 1, 2
Not surprisingly, the disfiguring nature of the disease often comes with social stigma and misconceptions that have a significant psychosocial impact. Up to 35 % of those with psoriasis report depressive symptoms, and up to 80 % report that the disease impacts negatively on their quality of life. 9
Existing evidence suggests that psoriasis clearly interferes with forming and keeping relationships, sexual function, everyday activities, studying, sports, and other physical activities. 9
Unfortunately, these factors can also make psoriasis patients even more vulnerable to the propagation of the aforementioned physical comorbidities. Other symptoms reported by patients with psoriasis can include( but are not limited to) frustration, anger, shame, guilt, embarrassment, anxiety, and increased use of alcohol. 9
Similarly, in addition to the triggering factors mentioned, psychological stress can often precede the onset of psoriasis and can lead to flares. 9 Consider the psychological impact of the disease in determining disease severity and when developing a holistic care plan to manage patients with psoriasis.
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