Psoriasis - Introduction

Infrequently, the course of PsA has been associated with a syndrome known by the acronym SAPHO, whose letters form the symptoms:

Synovitis (inflammation in the joints).
Acne.
Pustule eruptions.
Hyperostosis (abnormal bony growths).
Osteolysis (bone destruction).

Prevalence of Psoriatic Arthritis. Estimates on its prevalence among those with psoriasis range from 2% to as high as 42%. AIDS patients and those with severe psoriasis are at higher risk for developing PsA.

Less Common Forms of Psoriasis
Psoriasis Form	Description of Skin Patches	Comments
Guttate Psoriasis	The patches are teardrop-shaped and erupt suddenly, usually over the trunk and often on the arms, legs, or scalp. The teardrop patches often resolve on their own without treatment.	Guttate psoriasis can occur as the initial outbreak of psoriasis, often in children and young adults one to three weeks after a viral or bacterial (usually streptococcal) respiratory or throat infection. A family history of psoriasis and stressful life events are also highly linked with the onset of guttate psoriasis. Guttate psoriasis can also develop in patients who have already had other forms of psoriasis most likely in people treated with widely-applied topical corticosteroid dressings.
Inverse Psoriasis	Patches usually appear as smooth inflamed patches without a scaly surface. They occur in the folds of the skin, such as under the armpits or breast or in the groin.	Inverse psoriasis may be especially resistant to treatment.
Seborrheic Psoriasis	Patches appear as red scaly areas on the scalp, behind the ears, above the shoulder blades, in the armpits or groin, or in the center of the face.	Psoriasis of the scalp may be especially resistant to treatment.
Nail Psoriasis	The characteristic signs are tiny white pits scattered in groups across the nail. Toenails and sometimes fingernails may have yellowish spots. Long ridges may also develop across and down the nail. The nail bed often separates from the skin of the finger and collections of dead skin can accumulate underneath the nail.	Over half of patients with psoriasis have abnormal changes in their nails, which may appear before other skin symptoms. In some cases, nail psoriasis is the only manifestation of psoriasis.
Generalized Erythrodermic Psoriasis (also called psoriatic exfoliative erythroderma)	This is a rare severe and form, in which the skin surface becomes scaly and red. The disease covers all or nearly all of the body.	About 20% of such cases evolve from psoriasis itself. It can also be caused by certain treatments of psoriasis. This condition can also erupt after withdrawal from other agents, including corticosteroids or synthetic antimalarial drugs.
Pustular Psoriasis	Patches become pus-filled and blister-like. The blisters eventually turn brown and form a scaly crust or peel off. Pustules usually appear on the hands and feet. (When they form on the palms and soles, the condition is called palmar-plantar pustulosis.)	Pustular psoriasis may erupt as the first occurrence of psoriasis or it may evolve from plaque psoriasis. A number of conditions may trigger pustular psoriasis, including infection, pregnancy, certain drugs, and metal allergies. It can also accompany other forms of psoriasis and be very severe.