Itch + Psoriasis

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Itch (Pruritus)

is an important but underestimated symptom in psoriasis. However, there is limited published research data available on both its prevalence and characteristics. Some studies suggest that its prevalence in psoriasis sufferers, from different parts of the world, ranges from between 70% and 90%. In one Study Researchers found that 83% of psoriatic patients suffered from itching and in 45% of these patients pruritus was a daily occurrence (in 32% “often” and in 13% “always”) 1

Functional brain imaging studies have shown that the itch-scratch cycle in humans can be tracked to specific regions of the brain, including areas related to reward, pain sensation, and addiction.

The Itch-Scratch-Rash cycle is commonly used to describe this ongoing, never ceasing, always constant itch. The itchier a patient feels, the more scratching of the skin that occurs and which ultimately lead to skin damage and the appearance of a red rash. Often, in chronic presentations it becomes a completely unconscious habit and patients are often not even aware that they are scratching. When a patient scratches, their skin becomes inflamed, this inflammation then causes the skin to itch even more, thus making it even harder for the patient to resist the urge to scratch. This vicious circle can become so severe that it causes sleeplessness, irritability, anxiety and stress. In extreme cases it can lead to significant excoriations (open, bloody and deep scratch wounds) on the lesions and the surrounding normal skin. In chronic psoriasis it can even cause severe lichenification (thickening of the skin) and pain.

One study found that itching was the most frequent complaint (64%) among patients hospitalized for psoriasis. A National Psoriasis Foundation USA survey of its members in 2001, reported that for 79% of sufferers – itch was the second most troublesome symptom after scaling. Psoriasis sufferers have indicated that the severity of their itching on a scale from one to 10 VAS scale (from mild, moderate to severe pruritus where scratched plaques bleed). Most described pruritus (itch) as a sensation of stinging (20%) and burning (15%); the intensity reflected by VAS scale was scored as mild only in 13%, moderate in 37% and severe in 33% of those surveyed. 75% percent of itch patients had to scratch until they bled. Itch was also found to be more severe and frequent at night with 50% reporting difficulty in falling asleep. 2, 3

Itching/Scratching can lead to the hypertrophy (enlargement) of cutaneous (skin) nerve endings, which in turn become more sensitive. For those psoriasis sufferers that have as their Primary trigger, flare-ups caused by the “Koebner Phenomenon” (in which skin injury e.g. tattoos, surgical procedures, cuts, insect bites or sunburn etc. elicits a disease response) scratching can continually exacerbate and worsen their condition. The “Koebner Phenomenon” affects between 11% to 75%, depending on various study results. 4

Where constant and vigorous scratching has occurred and plaque scales have been removed, pin point bleeding, known as the Auspitz sign can be observed.

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Studies have also shown that in people suffering from depression, and who suffer from itching due to a variety of causes, that there is a correlation between the severity of itchiness and the severity of depression. Itching therefore causes both a real serious physical and psychological suffering, similar to what chronic pain does.5 It has been noted that there is a direct positive relationship between the severity of pruritus and the severity of depression in patients with psoriasis.6 One study revealed that patients with psoriasis, that experienced intense pruritus, also reported significantly higher scores for depression and anxiety, and showed personality traits of somatic anxiety, embitterment, mistrust, and physical trait aggressiveness. It was also noted that approximately 30% of these patients experienced high-level pruritus, when the great majority of patients had very few skin lesions.7

Patients when answering the questions on “what was the aggravating factors of pruritus”, gave the following answers –  “when I was stressed out” (35.0%), followed by “in a hot environment” (18.8%), “when sweating” (17.5%), “during a change in the weather” (12.5%), and “in a cold environment” (10.0%). Of these patients, 32.5% complained of itching on the entire body, followed by the scalp and trunk (17.5%), the scalp only (16.3%), and the scalp and extremities (13.8%).8

Scratching, even for adults, is difficult to resist because it does give the impression of easing the itch – but this is only for the short-term. Eventually the sensation to itch comes back – even worse that before the patient scratched.

Basic tips to control the urge to itch:- 

  • Keep nails short to avoid tearing the skin when scratching. 
  • Keep cool. Over-heating can trigger the itch. Try to keep your body temperature as constant as you can, wear light layers of cotton clothes.
  • Avoid overheated rooms, keep ducted heating to a minimum, and at night keep the bedrooms cold.
  • Avoid heavy blankets and doonas – use cotton blankets (hospital style) if possible. 
  • Gently rub with the back of the fingers, place pressure on the area instead of scratching. 
  • Use a cold compress 

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REFERENCES:

  1. Aerlyn D. “Treating Itch in Psoriasis.” Dermatology Nursing 18.32006 227-233. 20 Apr. 2008. http://www.medscape.com/viewarticle/541971.
  2. “Itch Relief.” Psoriasis.org. 9 Nov. 2001. National Psoriasis Foundation. 20 Apr. 2008.
    http://www.psoriasis.org/news/stories/2001/20011109_itch.php.
  3. Prigninao P. et al.; Itch in psoriasis: epidemiology, clinical aspects and treatment options.; Clinical, Cosmetic and Investigational Dermatology 2009:2 9–13
  4. Sampogna, F. “Prevalence of Symptoms Exerienced by Patients with Different Clinical Types of Psoriasis.”British Journal of Dermatology 151.3 Sep. 2004. 594-599. 20 Apr. 2008. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2133.20.
  5. Thappa, D.M. “The Isomorphic Phenomenon of Koebner.” Indian Journal of Dermatology, Venereology and Leprology 70.32004 187-189. 23 Apr.2008. http://www.ijdvl.com/text.asp?2004%2F70%2F3%2F187%2F11105.
  6. Gupta MA.et al. Pruritus in psoriasis. A prospective study of some psychiatric and dermatologic correlates. Arch Dermatol 1988; 124: 1052–1057.
  7. Remröd C. et al.; Psychological aspects of pruritus in psoriasis; Acta Derm Venereol 2015; 95: 439–443
  8. Tae-Wook Kim et al.; Clinical Characteristics of Pruritus in Patients with Scalp Psoriasis and Their Relation with Intraepidermal Nerve Fiber Density; Ann Dermatol Vol. 26, No. 6, 2014

TYPES OF PSORIASIS – PLAQUE PSORIASIS

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Plaque psoriasis or Psoriasis vulgaris (common type) – affects between 58% and 97% of all psoriasis cases. The difference in prevalence can be explained by race and geographical placement.1

It is characterized by sharply demarcated erythematous (red), silvery (whitish/yellowish), scaling plaques which most commonly occur on the elbows, knees, scalp, chest, back, and groin regions. The lesions are well-defined round or oval plaques that differ in size and in chronic plaque psoriasis often coalesce to form very large lesions covering large areas of the body.  Other involved areas include the ears, glans penis, perianal region, and sites of repeated trauma.

The lesions vary in size from 0.5 cm in diameter to large confluent areas on the trunk and limbs. There is a sharp line of demarcation between a plaque and clinically normal, uninvolved skin. Longitudinal studies of individual plaques have demonstrated that plaques are dynamic with an active and expanding edge, sometimes to the extent that the advancing edge may become annular leaving clinically normal skin in the centre of the original plaque.2,3

Plaque psoriasis can present in several different ways.

plaque-psoriasis

Figure 1. Plaque Psoriasis – colour varies from pinkish red to deep red, shiny with minimal silvery scale. Multiple lesions often coalesce forming larger plaques. This patient would be classified has having sever psoriasis

rupioid-sub-type

Figure 2. Plaque Psoriasis –  Rupioid subtype  Deep violaceous annular (round) lesions with distinctive, thickened, silvery scale. Multiple small lesions can be seen to be coalescing.

The term rupioid relates to distinct morphological subtype of plaque psoriasis. Rupioid plaques are small (2–5 cm in diameter) and highly hyperkeratotic, resembling limpet shells (see Figure 2).

A white blanching ring, known as Woronoff’s ring, may be observed in the skin surrounding a psoriatic plaque.

Other morphological subtypes of plaque psoriasis:-

  • Psoriasis gyrate — Figure 3 – in which curved linear patterns predominate annular psoriasis (psoriasis annularis – see figure 7 & 8) )—in which ring-like lesions develop secondary to central clearing

gyrate-sub-type Figure 3

  • Psoriasis follicularis — Figure 4 – in which minute scaly papules are present at the openings of pilosebaceous (hair) follicles.

Psoriasis - Folicularis Figure 4

  • Ostraceous psoriasis (see Figures 5 & 6 below) refers to hyperkeratotic plaques –  extremely thick scaled plaques often resembling an oyster shell.

ostraceous-fig-6 Figure 5                ostraceous-fig-5 Figure 6

Plaque psoriasis (see Figures 7 & 8 below) with a discoid (circular or oval) appearance is called psoriasis annularis or annular psoriasis.

psoriasis-annularis-fig-8 Figure 7                  Psoriasis - Annularis Figure 8 

Scale is typically present in plaque psoriasis, is characteristically silvery white, but may appear a yellowish colour and can vary in thickness.

Removal of scale may reveal tiny bleeding points (Auspitz sign – See Figure 9). The amount of scaling varies among patients and even at different sites on a given patient. In acute inflammatory or exanthematic psoriasis, scaling can be minimal and erythema may be the predominant clinical sign.4

OLYMPUS DIGITAL CAMERA
Figure 9. Thickened, red lesions with fine silvery scale. Multiple lesions have coalesced to form a large plaque. Note the excoriations marks where the patient has scratched the surface of the plaque to reveal pinpoint capillary bleeding, known as Auspitz sign
  • Lichenified psoriasis (Figure 10 and 11) – thickened psoriasis caused by chronic scratching (eczematized)

lichenified-2 Figure 10        lichenified Figure 11

Elephantine psoriasis (Figure 12 and 13) – large persistent, leathery plaques 

Psoriasis - Elephantine 1  Figure 12                Psoriasis - Elephantine Figure 13

Presentation examples of Plaque Psoriasis

Plaque Psoriasis 11 plaque-psoriasis-10  Plaque Psoriasis 9

plaque-psoriasis-8 plaque-psoriasis-7 plaque-psoriasis-6 plaque-psoriasis-5

Plaque Psoriasis 4 plaque-psoriasis-3  plaque-psoriasis-2 plaque-psoriasis-1

Read also “Psoriasis – Severity and Types”