Open access peer-reviewed chapter

Clinical Presentation of Psoriasis

Written By

Ananya Datta Mitra and Anupam Mitra

Submitted: May 17th, 2012 Reviewed: January 16th, 2013 Published: April 17th, 2013

DOI: 10.5772/55866

Chapter metrics overview

2,432 Chapter Downloads

View Full Metrics

1. Introduction

Psoriasis, a chronic papulosquamous inflammatory skin disease, was originally thought of as a primary disorder of epidermal keratinocytes, but is later on recognized as one of the commonest immune-mediated disorders [1, 2]. Although psoriasis starts with the involvement of skin, but limiting this disease to a skin problem is rather a restrictive approach. Psoriasis has been linked to a number of other diseases especially metabolic derangements and arthritis [3-5]. The disease imparts a huge socio-economic burden [6, 7] and the diagnosis of psoriasis is purely based on clinical features. Depending upon the type of psoriasis, onset may be abrupt or slowly progressive. Although it may appear at any age, but majority of patients experience the first episode before the age of 40 years and is uncommon before 10 years [8]. The population based study at Mayo Clinic, suggest that psoriasis tends to appear at an earlier age in females compared to males [9]. A study by Henseler et al. suggested that many psoriatic patients show bimodal distribution i.e. peak between 16-22 years and later between 57-60 years [2, 10].

Advertisement

2. Epidemiology of psoriasis

Psoriasis shows a worldwide prevalence. The estimate of prevalence psoriasis varies among different ethnic groups and also by geographical location, more common in colder northern zone compared to tropical zone and has been reported to vary in between 0 to 11.8% [11, 12]. Several confounding factors need to be taken into consideration for analyzing the prevalence data of psoriasis namely: method of ascertainment (population based, clinic based, questionnaire based), age and type of prevalence estimated (point, period, lifetime) [8, 13]. Taking into consideration of the confounding factors, the prevalence of psoriasis is highest in northern Europeans and almost absent in aboriginal population of south America [11]. In United States, the prevalence of psoriasis ranges between 2.2% to 2.6% and is lower in African-american compared to Caucasians. The prevalence rate of psoriasis in China and Japan is low than European ethnicity and in India it ranges between 0.5% to 2.3% [8, 13-15].

Advertisement

3. Latent, minimal and overt psoriasis

The course of the disease in the same individual is not uniform over time. It may range from apparently healthy to minor signs to overt clinical manifestations. No diagnostic test is available to predict future psoriasis development, that’s why the diagnosis of “latent psoriasis” in individuals without a previous history of the disease remains impossible. On the other hand, the diagnosis of “minimal psoriasis” largely depends on subjective variation due to lack of validated criteria. The minor signs of psoriasis, which are also known as ‘stigmata of psoriasis’ are described in Table 1, but their contribution to overt psoriasis remains unknown.

Hyperkeratotic plaques on the exterior surface without scaling
Keratolysis like lesions of the palms and soles
Eczematous patches on palms and soles
Severe dandruff
Nail pitting
Sterile multiple paronychia
Subungual hyperkeratosis and onycholysis without fungal infection
Recalcitrant scaly otitis externa
Intertrigo with sharp marginated erythema
Sharply marginated penile erythema without fungal infection

Table 1.

Stigmata of psoriasis [16]

Advertisement

4. Classifying psoriasis: The clinical spectrum

Psoriasis is a disease of coexisting signs and symptoms characterized by scaly, erythematous lesions with sharply demarcated margins. It’s interesting to note that scaling prevails in the stable chronic plaque stage of psoriasis and erythema predominates in the unstable progressing lesions of guttate psoriasis. The lesions are itchy and bleed easily. One of the classical sign of psoriasis is the ‘Auspitz’ sign, characterized by pinpoint bleeding when outer scales are removed from psoriatic plaques. Psoriasis cannot be classified based on a single factor and generally involves differentiation of lesions based on: a. morphology of the lesions, b. degree of inflammation, c. distributing patterns of the lesions, d. extent of body surface involvement, e. first onset and f. velocity of propagation [17].

4.1. Chronic plaque psoriasis

This is the commonest form of psoriasis, represents 70-80% of psoriatic patients and is also known as Psoriasis vulgaris. The patient presented with sharply demarcated round-oval, or nummular (coin-sized) plaques with a loosely adherent silvery white scale, specially affecting the elbows, knees, lumbosacral areal, intergluteal cleft and scalp (Figure 1 & 2). The lesions usually begin as erythematous macules or papules, extend peripherally, and coalesce to form plaques. Woronoff’s ring, a white blanching ring may be observed in the skin surrounding a psoriatic plaque [18, 19]. The gradual peripheral extension of the plaques resulting in different configurations including:

  1. psoriasis gyrate: predominantly curved linear pattern

  2. annular psoriasis: ring like lesions develop secondary to central clearing

  3. psoriasis follicularis: presence of tiny scaly papules at the openings of pilosebaceous follicles

Occasionally, presence of lesions on the scalp and face makes it difficult to separate this variety from seborrheic dermatitis (sebopsoriasis). There are two distinct morphological subtypes of plaque psoriasis: Rupioid and Ostraceous. Rupioid plaques resembles limpet shells, small (2-5 cm in diameter) and highly hyperkeratotic. Ostraceous psoriasis is characterized by hyperkeratotic plaques, relatively concave centres, resembles oyster shells. Scale is typically present in psoriasis, is characteristically silvery white, and can vary in thickness. Removal of scale may reveal tiny bleeding points (Auspitz sign). The amount of scaling varies among patients and even at different sites on a given patient. Apart from its usual presentation, chronic plaque psoriasis sometimes affecting the flexures such as inframammary, axillary and perineal region known as inversepsoriasis.Inverse psoriatic lesions have minimal or no scales and appear as red, shiny, well demarcated plaques and may be confused with candidal, intertrigo, and dermatophyte infections.

The lesions are steady over time and as they regress, they start with central clearing with a peripheral activity margin which produces an annular or polycyclic appearance of the lesions. Central clearing is sometimes associated with hypopigmentation. Although the lesions are benign but may be complicated by appearance of inflammation with pustules and peripheral extension of the lesions.

Figure 1.

Localized plaque psoriasis

Figure 2.

Generalized plaque psoriasis

4.2. Guttate psoriasis

Guttate psoriasis came from the Greek word ‘gutta’, which means droplet. Guttate psoriasis accounts for 2% of the total psoriasis [19]. This variety is distinguished by its acute onset of round erythematous exanthem (2-10 mm diameter) over the trunk and extremities in a centripetal fashion. The number of lesions may vary from 5 to more than 100 (Figure 3). Although the disease has a self limiting course, but a certain percentage of individuals may evolve to chronic plaque psoriasis. It is often reported that about 10% of psoriatic patients with the chronic plaque psoriasis have flares of guttate lesions during the course of their disease [18]. Guttate psoriasis commonly affect children or young adults with family history of psoriasis and may follow streptococcal infection and/or acute stressful life events [20]. It is estimated that there is a 40% increased risk of developing chronic psoriasis after a bout of guttate variety [21]. It’s quite interesting to note that chronic plaque psoriasis and guttate psoriasis appear to be genetically similar with a strong association to the PSORS1genetic locus, which is also a major determinant of Psoriasis vulgaris [22, 23].

Figure 3.

Guttate psoriasis

4.3. Generalized pustular psoriasis (von Zumbusch)

Generalized pustular psoriasis is rare and represents active, unstable disease. Population survey reports that almost 20% of patients have pustular lesions superimposed on lesions of chronic plaque psoriasis at any time during the course of the disease [16]. However, only 2-5% of psoriatic patients have predominant pustular variety, having only pustules dominating the clinical picture [24]. Acute generalized pustular psoriasis generally develops after an irritant topical treatment of plaque psoriasis or due to abrupt corticosteroid withdrawal [25, 26]. Onset of an acute generalized pustular psoriasis is characterized by red and tender skin with systemic symptoms like fever, anorexia and nausea. Within hours, innumerable pustules appear with an erythematous background. Later on pustules become confluent creating ponds of pus with severe systemic symptoms. Consequently, the pustules dry and skin exfoliates producing a glazed erythematous surface where new crops of pustules might appear. There may be geographic tongue, polyarthritis and cholestasis associated with generalized pustular psoriasis [27]. Patients with generalized pustular psoriasis often need hospitalization for management. With remission of acute episodes, patient either follows an erythrodermic state or may produce plaque like lesions. Rarely, pustular psoriasis may appear during first six months of pregnancy, being called impetigo herpetiformis[28].

4.4. Localized pustular psoriasis

Localized pustular psoriasis includes two clinicaly distinct varieties: acrodermatitis continua of Hallopeau and palmoplantar pustulosis.

Acrodermatitis continua(dermatitis repens): A rare pustular eruption of the fingers and toes initiated after a localized trauma starting at the tip of a single digit [29]. Subsequently, the pustules become confluent and may spread proximally to involve the dorsal aspects of the hands, forearms and feet. Eventually, patients may develop osteolysis of the distal phalanx and associated onychodystrophy and anonychia of the involved digits. Sometimes the pustules become generalized.

Palmoplantar pustulosis:The characterizing feature of this variety is hyperkeratosis and clusters of sterile, yellow pustules on a background of erythema and scaling, affecting the ventral aspect of palms and/or soles. The pustules are tender and form dark brown color with adherent scales or crust. It is frequently associated with psoriatic nail involvement. In almost 25% cases, it is associated with psoriasis vulgaris, but it is now believed that palmoplantar pustulosis may not be a form of psoriasis due to lack of genetic association with PSORS1 locus. Moreover, it is predominant in women and is strongly associated with smoking [23, 30]. This disease has been associated with pustulotic arthroosteitis involving the anterior chest wall, sacroiliitis, and peripheral synovitis [31, 32]. Palmoplantar pustulosis is also an element of SAPHO syndrome, characterized by synovitis, acne, pustulosis, hyperostosis, and osteitis [33].

4.5. Erythrodermic psoriasis

Psoriatic erythroderma is characterized by extensive involvement of the skin by active psoriasis and represents in one of the two forms (Figure 4). In one form, chronic plaque psoriasis gradually progress and involve extensive body surface. In the second form which is more serious, erythroderma is a manifestation of unstable psoriasis, which is precipitated by triggers such as infection, tar, drugs and withdrawal of corticosteroids. This unstable form of psoriasis is characterize by prominent erythema and loss of characteristic clinical features of psoriasis [34]. Erythroderma impairs the thermoregulatory capacity of the skin resulting in hypothermia, high output cardiac failure, and metabolic changes, which needs immediate inpatient care.

Figure 4.

Erythrodermic psoriasis

Figure 5.

Nail changes

4.6. Psoriatic nail disease

In psoriasis, finger nails are more commonly affected than toe nails. ‘Pitting of nail’ i.e. small pits in the nail plate are the commonest finding, resulting from defective nail formation in the proximal portion of the nail matrix. In addition, the nail may detach from the nail bed known as onycholysis and ‘oil-spots’ i.e. orange-yellow areas can be seen beneath the nail plate (Figure 5). Moreover, the nail plate may become, thickened, dystrophic, discolored and yellow, keratinous material may collect under the nail plate, which is known as subungual hyperkeratosis. In most psoriatic patients, minor nail changes are observed and major nail abnormalities are usually associated with psoriatic arthritis and scalp involvement [19, 35].

Advertisement

5. Extension of the psoriatic spectrum beyond skin

Psoriasis is a systemic, chronic inflammatory disorder, occuring due to complex interplay of genetic, environmental and immunologic factors, predominantly affecting skin but can involve any organ systems of the body. Epidemiological studies in Caucasian and Asian populations show that patients with psoriasis suffer from other chronic inflammatory conditions with overlapping pathology, such as rheumatoid arthritis and inflammatory bowel disease, more frequently than patients without psoriasis [36, 37].

Psoriatic arthritis is a chronic inflammatory arthritis affecting about 5–25% of patients with psoriasis. The prevalence varies from 20–420 per 100,000 population across the world except in Japan where it is 1 per 100,000 [38]. Psoriatic arthritis has been defined as “an inflammatory arthritis occurring during the course of psoriasis and characterized by negative rheumatoid factor” [5]. Although arthritis typically occurs in fourth and fifth decade, no age is exempted with cases involving young children and elderly. There is no gender bias and both sexes are affected with a male to female ratio varying from 0.7:1 to 2.1:1. In majority of the patients (49–75%), arthritis follows chronic psoriasis of about 7–12 years duration. This follows onset of skin and joint disease in 10–37% patients simultaneously and lastly it can precede psoriasis in 6–18% [39-46]. Psoriatic arthritis is most commonly associated with psoriasis vulgaris. Conventionally, psoriatic arthritis can affect both the peripheral joints as well as the axial skeleton; thus, the joint involvement has been grouped into different subtypes. The original Moll and Wright classification criteria divided psoriatic arthritis into five subtypes: distal interphalangeal (DIP) predominant, symmetrical polyarthritis, single or few fingers or toe joints involved (asymmetrical oligoarthritis and monoarthritis), predominant spondylitis, and arthritis mutilans [47].

Psoriasis can be associated with a range of co-morbidities that include metabolic diseases, such as diabetes and cardiovascular (CV) diseases, tumors of specific sites, such as, lung cancer, colon cancer, and kidney cancer [48] and psychological disorders such as depression [49-55]. These comorbidities might influence patients’ health and quality of life (QoL), and contribute to the 3 to 4 year reduction in life expectancy in patients of severe psoriasis [56]. There have been associations of psoriasis with smoking and increased body mass index [4, 57], which may influence clinical severity and prognosis. Established psoriasis has been associated with the several components of the metabolic syndrome, including hypertension, dyslipidemia, obesity, and impaired glucose tolerance [3, 49, 58]. It has been reported that suppression of the inflammatory process may reduce the cardiovascular risk in patients with psoriasis and rheumatoid arthritis [59, 60].

Advertisement

6. Grading the severity

Psoriasis, unlike many chronic disorders, does not emerge steadily toward a definite outcome, and therefore it is difficult to do staging of the disease by natural history [61]. Simple outcome measures like clinical remission, number of hospital admissions or ambulatory consultations and major disease flare-ups may affect disease severity. Measurement of disease severity only based on assessing skin area involvement at a point of time, has large limitations as it does not provide any direct information on the disease in terms of psychologic or social consequences. Moreover, differences between different pattern distributions or clinical subgroups in psoriasis except chronic plaque psoriasis, are inadequately addressed by these indices. The example for such measures is the Psoriasis Area and Severity Index (PASI), which was developed as an outcome measure in clinical trials on oral retinoids in 1978 [16, 62].

In this perspective, Quality of life (Qol) measures have the advantage of considering the multidimensional nature of disease assessment and outcome, which generally includes evaluation of disease related discomfort, level of disability and social disruption. However there is a limitation of their confirmation against a gold standard and the characterization of severity thresholds. Their use in clinical studies is still very limited. Qol refers to quantitative estimates acquired through standardized questionnaires exploring the relevant dimensions of the patient's life in terms of physical, social, and psychologic well being, that may be affected by the disease [63, 64]. Among the instruments designed for specifically assessing psoriasis are the Psoriasis Disability Index [65] and the Psoriasis Life Stress Inventory [66].

European Medicines Agency developed a set of criterion based on clinical features of psoriasis, involving a change in disease management from no treatment to topical and systemic modalities. These criterions are based on certain definitions which were developed to standardize assessment in randomized clinical trials. The definitions take into account; degree of skin involvement and patient’s opinion as for example 1) Minimal disease with few isolated lesions and disease in remission with no psoriatic lesions, 2) Mild disease with PASI<10% and well controlled with topical treatment, 3) Moderate disease with PASI>10% and can be treated topically, 4) Moderate to severe disease with PASI>10% and failure of topical therapy or PASI<10% with disabling lesions in face, hands and feet, 4) Severe disease with PASI>20% or PASI>10% and <20% with disabling lesions in face, hands and feet and 5) Psoraisis with guarded prognosis including Generalized pustular psoriasis and psoriatic erythroderma [67]. A careful distinction between severe diseases versus disease affecting Qol severely has relevant implications in disease management. Studies report that patients with mild psoriasis having a severe impact on Qol can benefit from psychologic support than systemic drugs to suppress disease activity [62].

Advertisement

7. Disease prognosis

Due to its chronicity and incurability, psoriasis has a comparatively higher prevalence in the general population. Generally, with age, the point prevalence and the lifetime prevalence is anticipated to increase but in many studies it was shown that prevalence does not increase or even diminish with age [17]. This may be due to increased mortality among psoriatic patients later in life as compared to general population. Association with smoking and other comorbidities might contribute to such a drift [68]. It has also been reported that Qol indices might decline in long run independent of treatment [69]. Moreover, the progression of the skin lesions does not follow a pattern and the extent of skin involvement might range erratically from none to generalized body involvement. However, according to population surveys, most patients experience mild to moderate symptoms [70] and the percentage of patients reporting systemic therapies and/or hospitalization is no more than 20% [18].

The disease course is a bit unpredictable with spontaneous remissions and exacerbations with disease severity increasing in the winter and improving in the summer months. Again, there may be a disease flare up during sun exposure. The prevalence of photosensitive psoriasis according to a cross sectional survey was about 5.5% in patients who have type 1 skin, have a positive family history, in advanced age group and having psoriasis on their hands [71]. Moreover, psoriasis is reported to improve with pregnancy and aggravate during post partum period [72].

Advertisement

8. Differential diagnosis

The papulosquamous diseases which are considered in the differential diagnosis of psoriasis includes tinea infections, pityriasis rosea, and lichen planus. Psoriatic lesions are distinct from these entities being very well circumscribed, circular, red papules or plaques with a grey or silvery-white dry scale. In addition, psoriatic lesions are typically distributed symmetrically on the scalp, elbows, knees, lumbosacral area, and in the body folds. Psoriasis may develop at the site of trauma, known as Koebner’s phenomenon.

Acute generalized exanthematic pustulosis, a self limiting febrile drug reaction usually resolving in 2 weeks after withdrawal of the suspected agent must be differentiated from generalized pustular psoriasis. Acute generalized exanthematic pustulosis is characterized by pinpoint nonfollicular pustules on erythematous patches mainly involving body folds, with single necrotic cells in epidermis, eosinophils and vasculitic changes in the dermis [73, 74].

Advertisement

9. To conclude

Psoriasis is an enigmatic disease involving a complex interplay of genetic, immunological and environmental factors. Advancement of science and technology has led to the identifications of many checkpoints in the disease course and pathology, which quite effectively has led to the development of novel therapeutic targets to limit disease progression. However, despite extensive research ino this disease the exact pathogenesis and clinical course of the disease is still unknown. Thus there is always a need for better diagnostic criteria, severity assessments and disease related Qol measures for determining long term outcomes of this elusive disease.

Advertisement

Acknowledgments

The images of clinical presentation of psoriasis are kind gifts from our mentor and eminent professor of Rheumatology and Dermatology, Dr. Siba P Raychaudhuri of University of California, Davis, CA, USA.

References

  1. 1. RaychaudhuriS. PA Cutting Edge Overview: Psoriatic Disease.Clin Rev Allergy Immunol201
  2. 2. GriffithsC. EBarker JN: Pathogenesis and clinical features of psoriasis.Lancet2007
  3. 3. McdonaldC. JCalabresi P: Psoriasis and occlusive vascular disease.Br J Dermatol1978
  4. 4. NaldiLChatenoudLLinderDBelloni Fortina A, Peserico A, Virgili AR, Bruni PL, Ingordo V, Lo Scocco G, Solaroli Cet al: Cigarette smoking, body mass index, and stressful life events as risk factors for psoriasis: results from an Italian case-control study.J Invest Dermatol2005
  5. 5. HelliwellP. STaylor WJ: Classification and diagnostic criteria for psoriatic arthritis.Ann Rheum Dis2005Suppl 2:ii38
  6. 6. JoblingRNaldi L: Assessing the impact of psoriasis and the relevance of qualitative research.J Invest Dermatol2006
  7. 7. LiKArmstrongA. WA review of health outcomes in patients with psoriasis.Dermatol Clin2012viii.
  8. 8. GudjonssonJ. EElder JT: Psoriasis: epidemiology.Clin Dermatol2007
  9. 9. BellL. MSedlackRBeardC. MPerryH. OMichetC. JKurland LT: Incidence of psoriasis in Rochester, Minn,19801983Arch Dermatol1991
  10. 10. 10.HenselerTChristophers E: Psoriasis of early and late onset: characterization of two types of psoriasis vulgaris.J Am Acad Dermatol1985
  11. 11. RaychaudhuriS. PFarber EM: The prevalence of psoriasis in the world.J Eur Acad Dermatol Venereol2001
  12. 12. Farber EM NL: Epidemiology: natural history and geneticsIn:Roenigk Jr HH, Maibach HI, editorsNew York: Dekker19981998107157
  13. 13. ChandranVRaychaudhuri SP: Geoepidemiology and environmental factors of psoriasis and psoriatic arthritis.J Autoimmun2010J314321
  14. 14. Lin XR: Psoriasis in ChinaJ Dermatol1993
  15. 15. GelfandJ. MSternR. SNijstenTFeldmanS. RThomasJKistJRolstadTMargolis DJ: The prevalence of psoriasis in African Americans: results from a population-based study.J Am Acad Dermatol2005
  16. 16. NaldiLGambini D: The clinical spectrum of psoriasis.Clin Dermatol2007
  17. 17. Naldi L: Epidemiology of psoriasisCurr Drug Targets Inflamm Allergy2004
  18. 18. NaldiLColomboPPlacchesiE. BPiccittoRChatenoudLLa Vecchia C: Study design and preliminary results from the pilot phase of the PraKtis study: self-reported diagnoses of selected skin diseases in a representative sample of the Italian population.Dermatology2004
  19. 19. LangleyR. GKruegerG. GGriffiths CE: Psoriasis: epidemiology, clinical features, and quality of life.Ann Rheum Dis2005Suppl 2:ii1823discussion ii24-15.
  20. 20. NaldiLPeliLParazziniFCarrel CF: Family history of psoriasis, stressful life events, and recent infectious disease are risk factors for a first episode of acute guttate psoriasis: results of a case-control study.J Am Acad Dermatol2001
  21. 21. MartinB. AChalmersR. JTelfer NR: How great is the risk of further psoriasis following a single episode of acute guttate psoriasis?Arch Dermatol1996
  22. 22. SagooG. STazi-ahniniRBarkerJ. WElderJ. TNairR. PSamuelssonLTraupeHTrembathR. CRobinsonD. AIles MM: Meta-analysis of genome-wide studies of psoriasis susceptibility reveals linkage to chromosomes 621and 4q28-q31 in Caucasian and Chinese Hans population.J Invest Dermatol2004
  23. 23. AsumalahtiKAmeenMSuomelaSHagforsenEMichaelssonGEvansJMunroMVealCAllenMLemanJet alGenetic analysis of PSORS1 distinguishes guttate psoriasis and palmoplantar pustulosis.J Invest Dermatol2003
  24. 24. KawadaATezukaTNakamizoYKimuraHNakagawaHOhkidoMOzawaAOhkawaraAKobayashiHHaradaSet alA survey of psoriasis patients in Japan from1982to 2001.J Dermatol Sci2003, 31(1):59-64.
  25. 25. OhkawaraAYasudaHKobayashiHInabaYOgawaHHashimotoIImamura S: Generalized pustular psoriasis in Japan: two distinct groups formed by differences in symptoms and genetic background.Acta Derm Venereol1996
  26. 26. ZelicksonB. DMuller SA: Generalized pustular psoriasis. A review of 63 cases.Arch Dermatol1991
  27. 27. ViguierMAllezMZagdanskiA. MBertheauPDe KervilerERybojadMMorelPDubertretLLemannMBachelez H: High frequency of cholestasis in generalized pustular psoriasis: Evidence for neutrophilic involvement of the biliary tract.Hepatology2004
  28. 28. OumeishO. YParish JL: Impetigo herpetiformis.Clin Dermatol2006
  29. 29. RosenbergB. EStrober BE: Acrodermatitis continua.Dermatol Online J2004
  30. 30. ODohertyCJ, MacIntyre C: Palmoplantar pustulosis and smoking.Br Med J (Clin Res Ed)1985
  31. 31. KasperczykAFreyschmidt J: Pustulotic arthroosteitis: spectrum of bone lesions with palmoplantar pustulosis.Radiology1994
  32. 32. SzantoELinse U: Arthropathy associated with palmoplantar pustulosis.Clin Rheumatol1991
  33. 33. HayemGBouchaud-chabotABenaliKRouxSPalazzoESilbermann-hoffmanOKahnM. FMeyer O: SAPHO syndrome: a long-term follow-up study of 120 cases.Semin Arthritis Rheum1999
  34. 34. BalasubramaniamPBerth-Jones J: Erythroderma: 90% skin failure.Hosp Med2004
  35. 35. SalomonJSzepietowskiJ. CProniewicz A: Psoriatic nails: a prospective clinical study.J Cutan Med Surg2003
  36. 36. AugustinMReichKGlaeskeGSchaeferIRadtke M: Co-morbidity and age-related prevalence of psoriasis: Analysis of health insurance data in Germany.Acta Derm Venereol2010
  37. 37. TsaiT. FWangT. SHungS. TTsaiP. ISchenkelBZhangMTang CH: Epidemiology and comorbidities of psoriasis patients in a national database in Taiwan.J Dermatol Sci2011
  38. 38. AlamanosYVoulgariP. VDrosos AA: Incidence and prevalence of psoriatic arthritis: a systematic review.J Rheumatol2008
  39. 39. GladmanD. DShuckettRRussellM. LThorneJ. CSchachter RK: Psoriatic arthritis (PSA)--an analysis of 220 patients.Q J Med1987
  40. 40. JonesS. MArmasJ. BCohenM. GLovellC. REvisonGMcHugh NJ: Psoriatic arthritis: outcome of disease subsets and relationship of joint disease to nail and skin disease.Br J Rheumatol1994
  41. 41. Torre Alonso JCRodriguez Perez A, Arribas Castrillo JM, Ballina Garcia J, Riestra Noriega JL, Lopez Larrea C: Psoriatic arthritis (PA): a clinical, immunological and radiological study of 180 patients.Br J Rheumatol1991
  42. 42. MadlandT. MApalsetE. MJohannessenA. ERosseboBBrun JG: Prevalence, disease manifestations, and treatment of psoriatic arthritis in Western Norway.J Rheumatol2005
  43. 43. ZismanDEderLEliasMLaorABittermanHRozenbaumMFeldJRimarDRosner I: Clinical and demographic characteristics of patients with psoriatic arthritis in northern Israel.Rheumatol Int2012
  44. 44. MichetC. JMasonT. GMazlumzadeh M: Hip joint disease in psoriatic arthritis: risk factors and natural history.Ann Rheum Dis2005
  45. 45. TaylorWGladmanDHelliwellPMarchesoniAMeasePMielants H: Classification criteria for psoriatic arthritis: development of new criteria from a large international study.Arthritis Rheum2006
  46. 46. NossentJ. CGran JT: Epidemiological and clinical characteristics of psoriatic arthritis in northern Norway.Scand J Rheumatol2009
  47. 47. MollJ. MWright V: Psoriatic arthritis.Semin Arthritis Rheum1973
  48. 48. NaldiLChatenoud L: [Psoriasis and cancer: more than a chance link].Ann Dermatol Venereol2006
  49. 49. HenselerTChristophers E: Disease concomitance in psoriasis.J Am Acad Dermatol1995
  50. 50. NeimannA. LShinD. BWangXMargolisD. JTroxelA. BGelfand JM: Prevalence of cardiovascular risk factors in patients with psoriasis.J Am Acad Dermatol2006
  51. 51. EspositoMSaracenoRGiuntaAMaccaroneMChimenti S: An Italian study on psoriasis and depression.Dermatology2006
  52. 52. SommerD. MJenischSSuchanMChristophersEWeichenthal M: Increased prevalence of the metabolic syndrome in patients with moderate to severe psoriasis.Arch Dermatol Res2006
  53. 53. GelfandJ. MNeimannA. LShinD. BWangXMargolisD. JTroxel AB: Risk of myocardial infarction in patients with psoriasis.JAMA2006
  54. 54. MallbrisLAkreOGranathFYinLLindelofBEkbomAStahle-Backdahl M: Increased risk for cardiovascular mortality in psoriasis inpatients but not in outpatients.Eur J Epidemiol2004
  55. 55. KimballA. BJacobsonCWeissSVreelandM. GWu Y: The psychosocial burden of psoriasis.Am J Clin Dermatol2005
  56. 56. GelfandJ. MTroxelA. BLewisJ. DKurdS. KShinD. BWangXMargolisD. JStrom BL: The risk of mortality in patients with psoriasis: results from a population-based study.Arch Dermatol2007
  57. 57. McgowanJ. WPearceD. JChenJRichmondDBalkrishnanRFeldman SR: The skinny on psoriasis and obesity.Arch Dermatol2005
  58. 58. Lindegard B: Diseases associated with psoriasis in a general population of 159middle-aged, urban, native Swedes.Dermatologica1986
  59. 59. ProdanovichSMaFTaylorJ. RPezonCFasihiTKirsner RS: Methotrexate reduces incidence of vascular diseases in veterans with psoriasis or rheumatoid arthritis.J Am Acad Dermatol2005
  60. 60. ChoiH. KHernanM. ASeegerJ. DRobinsJ. MWolfe F: Methotrexate and mortality in patients with rheumatoid arthritis: a prospective study.Lancet2002
  61. 61. FarberE. MNall ML: The natural history of psoriasis in 5,600 patients.Dermatologica1974
  62. 62. SchmittJWozel G: The psoriasis area and severity index is the adequate criterion to define severity in chronic plaque-type psoriasis.Dermatology2005
  63. 63. WilsonI. BCleary PD: Linking clinical variables with health-related quality of life. A conceptual model of patient outcomes.JAMA1995
  64. 64. Katz S: The science of quality of lifeJ Chronic Dis1987
  65. 65. Finlay AY: Quality of life measurement in dermatology: a practical guideBr J Dermatol1997
  66. 66. ONeillPKellyP: Postal questionnaire study of disability in the community associated with psoriasis.BMJ1996
  67. 67. guidance ECfPMPNftreatment ociompift,2454opCE.
  68. 68. AdamsK. FSchatzkinAHarrisT. BKipnisVMouwTBallard-barbashRHollenbeckALeitzmann MF: Overweight, obesity, and mortality in a large prospective cohort of persons 50 to 71 years old.N Engl J Med2006
  69. 69. UnaezeJNijstenTMurphyARavichandranCStern RS: Impact of psoriasis on health-related quality of life decreases over time: an11year prospective study.J Invest Dermatol2006
  70. 70. GelfandJ. MFeldmanS. RSternR. SThomasJRolstadTMargolis DJ: Determinants of quality of life in patients with psoriasis: a study from the US population.J Am Acad Dermatol2004
  71. 71. RosA. MEklund G: Photosensitive psoriasis. An epidemiologic study.J Am Acad Dermatol1987Pt 1):752-758.
  72. 72. DunnaS. FFinlay AY: Psoriasis: improvement during and worsening after pregnancy.Br J Dermatol1989
  73. 73. SaissiE. HBeau-salinasFJonville-beraA. PLoretteGAutret-Leca E: [Drugs associated with acute generalized exanthematic pustulosis].Ann Dermatol Venereol2003
  74. 74. SidoroffAHalevySBavinckJ. NVaillantLRoujeau JC: Acute generalized exanthematous pustulosis (AGEP)--a clinical reaction pattern.J Cutan Pathol2001

Written By

Ananya Datta Mitra and Anupam Mitra

Submitted: May 17th, 2012 Reviewed: January 16th, 2013 Published: April 17th, 2013