Psoriasis Syndrome: Pathogenesis, Clinical Picture and Co-morbidities
Psoriasis is one of the most commonly encountered autoimmune pathologies in the dermatology clinic. It is described as a chronic inflammatory disease which is usually triggered in response to genetic predisposition and autoimmunity. The disease prevalence varies drastically in different geographical regions of the world, however it has been estimated to be approximately 0.9%-8.5% in the adult population worldwide (Parisi, Symmons, Griffiths, & Ashcroft, 2013). Modern clinical practice has gathered enormous scientific evidence which points to the fact that the clinical manifestations of psoriasis can no longer be ascribed to skin only, and that it may be considered as a multi-system syndrome (Oliveira Mde, Rocha Bde, & Duarte, 2015).
This review article aims to dissect psoriasis literature, and explore the endless list of co-morbidities that can be found in conjunction with psoriasis.
Pathogenesis of Psoriasis
The basic etiology of psoriasis is characterized by the development of uncontrolled immune responses directed against cutaneous layers of the body. The immune reaction involves activation of both innate and specific immune responses. This induces the proliferation of skin cells (keratinocytes) which then proceed to differentiation without any definite order, thereby leading to epidermal hyperplasia. This is also accompanied by the presence of inflammatory exudates in the skin layers. Apart from genetics, psoriasis may also be precipitated following trauma to the skin (termed as Koebner phenomenon), due to infections or drug reactions (Rendon & Schäkel, 2019).
Different Types and Clinical Correlations
Depending upon its characteristic lesions, psoriasis has been classified into the following major subtypes (Raychaudhuri, Maverakis, & Raychaudhuri, 2014; Weigle & McBane, 2013):
Well-demarcated and pruritic, scaly plaques which are pinkish red in color-this is the commonest clinical picture of psoriasis as seen by a physician. Plaque psoriasis, also called psoriasis vulgaris, accounts for up to 90% of the cases of this particular skin disease. This type mostly affects the thoracoabdominal region, the scalp, and the extensor surfaces of the arms and legs.
This type of psoriasis involves the formation of coalescing pustules without any plaques. Hands and feet are most commonly impacted by the disease.
It is characterized by the appearance of small pink-colored papules, usually appearing on the trunk. It is believed to be associated with streptococcal sore throat.
Inverse psoriasis can lead to the formation of eruptive, pruritic plaques or patches. It usually affects the flexor surfaces, and skin folds such as groin and axilla.
This form of psoriasis represents an emergency condition where as much as 90% of the body surface area may become erythematous due to an acute inflammatory process.
Co-morbidities in Patients with Psoriasis
Psoriasis being a systemic disease, can involve multiple organs and organ systems throughout the body. Some of the most heavily documented clinical manifestations are pertinent to the musculoskeletal, cardiovascular, gastrointestinal and endocrine systems (Kovitwanichkanont, Chong, & Foley, 2020). These non-dermatological aspects of the psoriatic disease are discussed below:
(1) Musculoskeletal Manifestations
It has been estimated that approximately 30% of the middle-aged population affected with psoriasis eventually develops psoriatic arthritis (Ocampo & Gladman, 2019). It is essential to achieve an early diagnosis of the pathology as timely recognition can verily save an individual from considerable joint dysfunction. Musculoskeletal system can suffer drastically through the following main mechanisms:
Psoriatic lesions of the synovial membrane
Destruction of the bone and cartilage
Disruption of tendon/ligament sheaths
The most commonly affected joints include those of the axial skeleton and small peripheral joints. Psoriatic arthritis is mostly accompanied by other features such as skin and nail involvement, sacroiliitis, uveitis, bowel infection, osteoporosis, and cardiovascular manifestations such as hypertension (Ocampo & Gladman, 2019). In addition, a major pathognomonic sign of psoriatic arthritis is enthesitis, or tendon/ligament sheath inflammation which is found among 70% of the affected population.
Being a variant of spondyloarthropathies (Coates & Helliwell, 2017), psoriatic arthritis usually presents with the following clinical signs:
Severe lower backache due to sacroiliitis
Asymmetrical pain, swelling, and stiffness in the small finger joints. This distinguishes it from the rheumatoid arthritis where symmetrical joint involvement takes place.
Skin and nail manifestations
Decline in visual acuity
Episodes of mild to moderate diarrhea
As evident from these findings, psoriatic arthritis can only be treated by the implementation of a meticulous multidisciplinary plan of action (Sankowski, Lebkowska, Cwikła, Walecka, & Walecki, 2013).
(2) Cardiovascular Manifestations
Cardiovascular disease risk increases substantially in the presence of systemic psoriasis. A few authors have reported that psoriatic population is at a twofold higher risk for developing arterial disease while modern studies have recognized psoriasis as an entirely independent risk factor in the etiology of coronary artery disease, and myocardial infarction. In the presence of any other accompanying cardiovascular risk factors, the incidence of heart disease can become more evident (Caiazzo et al., 2018).
Atherosclerosis has been found to be the main culprit in the pathogenesis of these vascular complications. This causation is mainly based on the hypothesis that the release of inflammatory mediators from skin lesions can trigger degenerative changes in the arterial walls. This even raises the suspicion that psoriasis could also increase the risk of cerebrovascular accidents or stroke. Moreover, peripheral vascular disease has also been added to the systemic manifestations of the disease (Kovitwanichkanont et al., 2020).
It has been suggested however, that the anti-inflammatory drugs used against psoriasis possess a moderate efficacy in the treatment of its cardiovascular complications.
(3) Gastrointestinal Manifestations
Psoriasis has also been associated with gastrointestinal inflammatory conditions which possess a strong autoimmune background. These include inflammatory bowel disease and celiac disease. A subpopulation of psoriatic patients may develop ulcerative colitis or Crohn’s disease, and this is mainly due to the presence of a common genetic predisposition. Psoriasis patients are also prone to develop irritable bowel syndrome or reflux esophagitis (Cottone, Sapienza, Macaluso, & Cannizzaro, 2019). Immunomodulatory therapy being utilized for psoriasis, has also shown some promise in the management of its gastrointestinal manifestations.
(4) Endocrine Manifestations
Metabolic syndrome has also been documented as a major complication of psoriasis (Gisondi, Fostini, Fossà, Girolomoni, & Targher, 2018). This clinical syndrome includes hyperlipidemia, insulin resistance and hyperglycemia, hypertension, and raised body-mass index (BMI). These clinical manifestations have been correlated with a multifactorial etiology. In addition, psoriasis also poses an immense threat to the integrity of liver where plaque psoriasis may precipitate fatty liver disease. Early detection of the contributing risk factors, and their timely elimination is the only useful intervention in the management of metabolic problems related to psoriasis.
(5) Psychological Depression
Recent studies have indicated that mental depression might be closely linked to psoriasis. It has been speculated that there exists an interconnecting link between the two, i.e., raised levels of pro-inflammatory cytokines. Similar findings have been reported for other chronic inflammatory conditions as well. Additionally, it is worth-noting that the anti-inflammatory drugs applicable for psoriasis have also been found to be useful for improving depressive symptoms but only in limited study samples (Patel et al., 2017).
(6) Risk of Malignancy
Psoriatic patients possess a relatively higher risk of various malignancies, some of which are mentioned below:
Lymphoproliferative disorders. e.g., Hodgkin’s lymphoma
Skin cancers (squamous cell carcinoma)
Gastrointestinal tract malignancy
With the aid of a detailed literature review, it has been made abundantly clear that psoriasis is a complex clinical syndrome which can portray an extremely versatile clinical picture. Being a chronic inflammatory state, it is often associated with various co-morbidities which can turn the clinical management of the condition into a physician’s nightmare. Nevertheless, it is advisable to screen the newly diagnosed patients for all the possible risk factors so as to prevent the development of any serious complications. Adopting a multidisciplinary approach can play a pivotal role in an efficient management of the psoriatic disease.
Caiazzo, G., Fabbrocini, G., Di Caprio, R., Raimondo, A., Scala, E., Balato, N., & Balato, A. (2018). Psoriasis, Cardiovascular Events, and Biologics: Lights and Shadows. Front Immunol, 9, 1668. doi:10.3389/fimmu.2018.01668
Coates, L. C., & Helliwell, P. S. (2017). Psoriatic arthritis: state of the art review. Clin Med (Lond), 17(1), 65-70. doi:10.7861/clinmedicine.17-1-65
Cottone, M., Sapienza, C., Macaluso, F. S., & Cannizzaro, M. (2019). Psoriasis and Inflammatory Bowel Disease. Dig Dis, 37(6), 451-457. doi:10.1159/000500116
Gisondi, P., Fostini, A. C., Fossà, I., Girolomoni, G., & Targher, G. (2018). Psoriasis and the metabolic syndrome. Clin Dermatol, 36(1), 21-28. doi:10.1016/j.clindermatol.2017.09.005
Kovitwanichkanont, T., Chong, A. H., & Foley, P. (2020). Beyond skin deep: addressing comorbidities in psoriasis. Med J Aust, 212(11), 528-534. doi:10.5694/mja2.50591
Ocampo, D. V., & Gladman, D. (2019). Psoriatic arthritis. F1000Res, 8. doi:10.12688/f1000research.19144.1
Oliveira Mde, F., Rocha Bde, O., & Duarte, G. V. (2015). Psoriasis: classical and emerging comorbidities. An Bras Dermatol, 90(1), 9-20. doi:10.1590/abd1806-4841.20153038
Parisi, R., Symmons, D. P., Griffiths, C. E., & Ashcroft, D. M. (2013). Global epidemiology of psoriasis: a systematic review of incidence and prevalence. J Invest Dermatol, 133(2), 377-385. doi:10.1038/jid.2012.339
Patel, N., Nadkarni, A., Cardwell, L. A., Vera, N., Frey, C., Patel, N., & Feldman, S. R. (2017). Psoriasis, Depression, and Inflammatory Overlap: A Review. Am J Clin Dermatol, 18(5), 613-620. doi:10.1007/s40257-017-0279-8
Raychaudhuri, S. K., Maverakis, E., & Raychaudhuri, S. P. (2014). Diagnosis and classification of psoriasis. Autoimmun Rev, 13(4-5), 490-495. doi:10.1016/j.autrev.2014.01.008
Rendon, A., & Schäkel, K. (2019). Psoriasis Pathogenesis and Treatment. Int J Mol Sci, 20(6). doi:10.3390/ijms20061475
Sankowski, A. J., Lebkowska, U. M., Cwikła, J., Walecka, I., & Walecki, J. (2013). Psoriatic arthritis. Pol J Radiol, 78(1), 7-17. doi:10.12659/pjr.883763
Weigle, N., & McBane, S. (2013). Psoriasis. Am Fam Physician, 87(9), 626-633.