Psoriasis 1 Psoriasis Psoriasis Classification and external resources Back and arms of a person with psoriasis [1] ICD-10 L40 [2] ICD-9 696 [3] OMIM 177900 [4] DiseasesDB 10895 [5] MedlinePlus 000434 eMedicine [6] [7] emerg/489 Dermatology:derm/365 plaque [8] derm/361 guttate [9] derm/363 nails [10] derm/366 pustular [11] Arthritis derm/918 [12] Radiology radio/578 [13] Physical Medicine pmr/120 [14] MeSH D011565 Psoriasis (/sɵˈraɪ.əsɨs/; from Greek ψωρίασις, meaning "itching condition" or "being itchy", from psora "itch" and -sis "action, condition"; also termed psoriasis vulgaris), is a common, chronic relapsing/remitting immune-mediated skin disease characterized by red, scaly patches, papules, and plaques, which usually itch. The skin lesions seen in psoriasis may vary in severity from minor localized patches to complete body coverage. The disease affects 2–4% of the general population. There are five main types of psoriasis: plaque, guttate, inverse, pustular, and erythrodermic. Plaque psoriasis is the most common form and typically manifests as red and white scaly patches on the top layer of the skin. Skin cells rapidly accumulate at these plaque sites and create a silvery-white appearance. Plaques frequently occur on the skin of the elbows and knees, but can affect any area, including the scalp, palms of hands and soles of feet, and genitals. In contrast to eczema, psoriasis is more likely to be found on the outer side of the joint. Fingernails and toenails are frequently affected (psoriatic nail dystrophy) and can be seen as an isolated sign. Inflammation of the joints in the Psoriasis 2 context of psoriatic disease, known as psoriatic arthritis, affects up to 30% of individuals with psoriasis. The causes of psoriasis are not fully understood. Psoriasis is not purely a skin disorder and can have a negative impact on many organ systems. Psoriasis has been associated with an increased risk of certain cancers, cardiovascular disease and other immune-mediated disorders such as Crohn's disease and ulcerative colitis. It is generally considered a genetic disease thought to be triggered or influenced by environmental factors. Psoriasis develops when the immune system mistakes a normal skin cell for a pathogen, and sends out faulty signals that cause overproduction of new skin cells. It is not contagious. Oxidative stress, stress, and withdrawal of a systemic corticosteroid have each been suggested as a trigger for psoriasis. Injury to the skin can trigger local psoriatic skin changes known as the Koebner phenomenon. No cure is available for psoriasis, but various treatments can help to control the symptoms. Though many treatments are available, psoriasis can be difficult to treat due to its chronic recurrent nature. A new generation of targeted immune therapies is being subjected to rigorous investigation in order to advance treatment options for psoriasis. Signs and symptoms Plaque Psoriasis vulgaris (also known as chronic stationary psoriasis or plaque-like psoriasis) is the most common form and affects 85%–90% of people with psoriasis. Plaque psoriasis typically appears as raised areas of inflamed skin covered with silvery white scaly skin. These areas are called plaques and are most commonly found on the elbows, knees, scalp, and back. Psoriatic erythroderma (erythrodermic psoriasis) involves widespread inflammation and exfoliation of the skin over most of the body surface. It may be accompanied by severe itching, swelling and pain. It is often the result of an exacerbation of unstable plaque psoriasis, particularly following the abrupt withdrawal Psoriatic plaque, showing a silvery center surrounded by a reddened border. of systemic glucocorticoids. This form of psoriasis can be fatal as the extreme inflammation and exfoliation disrupt the body's ability to regulate temperature and perform barrier functions. Plaques of psoriasis A person's arm Psoriasis of the palms covered with plaque psoriasis Psoriasis 3 Pustular See also: Generalized pustular psoriasis Pustular psoriasis appears as raised bumps filled with noninfectious pus (pustules). The skin under and surrounding the pustules is red and tender. Pustular psoriasis can be localized, commonly to the hands and feet (palmoplantar pustulosis), or generalized with widespread patches occurring randomly on any part of the body. Acrodermatitis continua is a form of localized psoriasis limited to the fingers and toes that may spread to the hands and feet. Pustulosis palmaris et plantaris is another form of localized pustular psoriasis similar to acrodermatitis continua with pustules erupting from red, tender, scaly skin found on the palms of the hands and the soles of the feet. Severe pustular psoriasis. Generalized pustular psoriasis (pustular psoriasis of von Zumbusch), also known as impetigo herpetiformis during pregnancy, is a rare and severe form of psoriasis that may require hospitalization. The development of generalized pustular psoriasis is often caused by an infection, abrupt withdrawal of topical corticosteroid treatment, pregnancy, hypocalcemia, medications, or following an irritating topical treatment for plaque psoriasis. This form of psoriasis is characterized by an acute onset of numerous pustules on top of tender red skin. This skin eruption is often accompanied by a fever, muscle aches, nausea, and an elevated white blood cell count. Annular pustular psoriasis (APP) is a rare form of generalized pustular psoriasis and is the most common type of pustular psoriasis seen during childhood. APP tends to occur in women more frequently than in men and is usually less severe than other forms of generalized pustular psoriasis such as impetigo herpetiformis. This form of psoriasis is characterized by ring-shaped plaques with pustules around the edges and yellow crusting. APP most often affects the torso, neck, arms, and legs. Other skin lesions Additional types of psoriasis affecting the skin include inverse psoriasis, guttate psoriasis, oral psoriasis, and seborrheic-like psoriasis. Inverse psoriasis (also known as flexural psoriasis) appears as smooth inflamed patches of skin. The patches frequently affect skin folds, particularly around the genitals (between the thigh and groin), the armpits, in the skin folds of an overweight abdomen (known as panniculus), between the buttocks in the intergluteal cleft, and under the breasts in the inframammary fold. Heat, trauma, and infection are thought to play a role in the development of this atypical form of psoriasis. Napkin psoriasis is a subtype of psoriasis common in infants characterized by red papules with silver scale in the diaper area that may extend to the torso or limbs. Napkin psoriasis is often misdiagnosed as napkin dermatitis. Guttate psoriasis is characterized by numerous small, scaly, red or pink, teardrop-shaped lesions (papules). These numerous spots of Example of guttate psoriasis. psoriasis appear over large areas of the body, primarily the trunk, but also the limbs and scalp. Guttate psoriasis is often preceded by a streptococcal infection, typically streptococcal pharyngitis. The reverse is not true. Oral psoriasis is very rare, in contrast to lichen planus, another common papulosquamous disorder that commonly involves both the skin and mouth. When psoriasis involves the oral mucosa (the lining of the mouth), it may be Psoriasis 4 asymptomatic, but it may appear as white or grey-yellow plaques. Fissured tongue is the most common finding in those with oral psoriasis and has been reported to occur in 6.5-20% of people with psoriasis affecting the skin. The microscopic appearance of oral mucosa affected by geographic tongue (migratory stomatitis) is very similar to the appearance of psoriasis. However, modern studies have failed to demonstrate any link between the two conditions. Seborrheic-like psoriasis is a common form of psoriasis with clinical aspects of psoriasis and seborrheic dermatitis and may be difficult to distinguish from the latter. This form of psoriasis typically manifests as red plaques with greasy scales in areas of higher sebum production such as the scalp, forehead, skin folds next to the nose, skin surrounding the mouth, skin on the chest above the sternum, and in skin folds. Psoriatic arthritis See also: Psoriatic arthritis Psoriatic arthritis is a form of chronic inflammatory arthritis that has a highly variable clinical presentation and frequently occurs in association with skin and nail psoriasis. It typically involves painful inflammation of the joints and surrounding connective tissue and can occur in any joint, but most commonly affects the joints of the fingers and toes. This can result in a sausage-shaped swelling of the fingers and toes known as dactylitis. Psoriatic arthritis can also affect the hips, knees, spine (spondylitis), and sacroiliac joint (sacroiliitis). Approximately 30% of individuals with psoriasis will develop psoriatic arthritis. Dermatologic manifestations of psoriasis tend to occur before arthritic manifestations in about 75% of cases. Nail changes Psoriasis can affect the nails and produces a variety of changes in the appearance of finger and toe nails. Nail psoriasis occurs in 40-45% of people with psoriasis affecting the skin and has a lifetime incidence of 80-90% in those with psoriatic arthritis. These changes include pitting of the nails (pinhead sized depressions in the nail-seen in 70% with nail psoriasis), whitening of the nail, small areas of bleeding from capillaries under the nail, yellow-reddish discoloration of the nails known as the