Classification of psoriasis

Source: Wikipedia

In contrast to eczema, psoriasis is more likely to be found on the outer side of the joint.
Some patients have no dermatological symptoms.
Local psoriatic changes can be triggered by an injury to the skin - Koebner phenomenon.

Psoriasis is classified into nonpustular and pustular types:

Non-pustular

• Psoriasis vulgaris: a.k.a. plaque psoriasis. The most common type (80%-90% of patients). Raised areas of inflamed skin covered with silvery white scaly skin.
• Psoriatic erythroderma: Inflammation and exfoliation of skin over most of the body. 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 of systemic Rx. Can be fatal, as the extreme inflammation and exfoliation disrupt the body's ability to regulate temperature and for the skin to perform barrier functions.

Pustular

Pustular psoriasis appears as raised bumps filled with non-infectious pus (pustules). The skin under and surrounding the pustules is red and tender. Can be localised, commonly to the hands and feet (palmoplantar pustulosis), or generalised with widespread patches occurring randomly on any part of the body. This classification includes:

• Generalised pustular psoriasis (of von Zumbusch)
• Pustulosis palmaris et plantaris
• Annular pustular psoriasis
• Acrodermatitis continua
• Impetigo herpetiformis (a form of severe pustular psoriasis occurring in pregnancy).

Other

• Drug-induced.
• Inverse psoriasis, a.k.a. flexural psoriasis. Occurs in skin folds, particularly around the genitals (between the thigh and groin), armits under an overweight stomach (pannus) under the breasts (inframammary fold). Aggravated by friction and sweat, and is vulnerable to fungal infections.
• Napkin psoriasis.
• Seborrhoeic-like psoriasis.
• Guttate psoriasis: Numerous small, scaly, red/pink, teardrop-shaped lesions over large areas of the body, primarily the trunk (also limbs and scalp). Often preceded by a streptococcal infection, typically streptococcal pharyngitis.
• Nail psoriasis: Discolouring, pitting, lines going across the nails, thickening of skin under nail, loosening and crumbling of the nail (onycholysis).
• Psoriatic arthritis: Joint and connective tissue inflammation. Can affect any joint but most common in the joints of fingers and toes. Can result in sausage-shaped swilling of fingers/toes (dactylitis). Can also affect the hips, knees and spine (spondylitis). 10%-15% of people with psoriasis have psoriatic arthritis.