Psoriasis is a common chronic skin disease that causes rashes. These rashes tend to be itchy and scaly and are most frequently seen on the knees, elbows, trunk, and scalp. This condition usually arises in cycles or flares, which can last for a few weeks or months before subsiding. While the exact underlying cause of psoriasis remains unknown, most experts believe that this condition results from a problem in the immune system.

Types of psoriasis
Many different types of psoriasis have been recognized, each distinguished by its own set of signs and symptoms.

1. Plaque psoriasis
Plaque psoriasis, also known as psoriasis vulgaris, is an autoimmune condition that causes the cells to reproduce quickly. As a result, thick, scaly patches begin to appear on the skin. While this most commonly affects the elbows, back, knees, and scalp, it can spread to the face, feet, genitals, hands, and legs in more severe cases.

Symptoms of plaque psoriasis include raised, discolored plaques with a white or silvery surface, cracks (fissures), bleeding, itchiness, and irritation or pain.

While the cause of this condition remains unknown, it may be triggered by certain foods or drinks, reactions to specific treatments, dry skin, emotional stress, skin injuries, or sun damage.

2. Guttate psoriasis
This psoriasis is most commonly seen in young adults but can also happen to adults. It tends to appear without a warning, generally after an infection like strep throat. Two main symptoms mark it.

• Patches on the skin
  The most telltale signs of guttate psoriasis are round or teardrop-shaped patches, which are pink or red. They are usually between 2 mm and 10 mm in width and most commonly appear on the torso, legs, and arms.
• Itchiness
  These patches are quite sensitive and irritated, resulting in constant itchiness.

3. Inverse psoriasis
This type of psoriasis develops in areas where the skin rubs against itself, i.e., the skin folds, which means that the scales and patches appear around the armpits, belly button, below the breasts, and the groin area. Common triggers for this condition include friction, sweating, and fungal infections.

The condition may occur with or without an infection. Symptoms in their most basic form include a shiny, smooth, and discolored rash (red, pink, brown, or purple), cracks in the skin, creases, itchiness, and moist patches of skin. An infection may also result in symptoms like pus-filled bumps in the affected areas, a foul smell, small cuts or tiny cracks on the skin, swelling, and tenderness.

4. Nail psoriasis
This form of psoriasis affects the skin under the nails and generally appears along with another psoriatic rash on the body. While it can affect anyone, it is most commonly seen among those over 40. There are three distinct symptoms of nail psoriasis.

• Discoloration
  The skin under the nails may change colors, turning yellow, red, pink, or brown. These are also called salmon patches or oil drop spots.
• Pits
  The nails may also develop pits called cupuliform depressions. These can be between 0.4 mm and 2 mm in size and may vary in depth.
• Changes in nail structure
  In some cases, individuals may also develop grooves that run across the nails, known as Beau’s lines. They may grow so thin and brittle in others that they break frequently. The thick skin under the tip of the nail may also start to peel, which could result in nail fungus.

5. Pustular psoriasis
Individuals with this form of psoriasis develop scaly, discolored patches of skin along with fluid-filled pustules or blisters. It can affect any part of the body, but the most common sites include the feet, scalp, face, and hands. Pustular psoriasis can be generalized (Von Zumbusch) or localized (acute psoriasis).

• Generalized pustular psoriasis (GPP)
  This condition affects large parts of the body and may include symptoms like fever, chills, severe itching, changes in heart rate, fatigue, and muscle weakness.
• Localized pustular psoriasis (LPP)
  This form of psoriasis affects a specific part of the body and may further be divided into two types.

There are a few other types, including Palmoplantar pustular psoriasis, which affects the hands and feet, and Acrodermatitis continua of Hallopeau (ACH), which affects the tips of the fingers and toes.

6. Erythrodermic psoriasis
In rare instances, the pustules on plaques can cover a major area of the body, causing erythrodermic psoriasis. Other symptoms like fever, chills, muscle weakness, fatigue, severe pain, itchiness, fast heart rate, dehydration, and swollen legs often accompany it. Erythrodermic psoriasis most frequently appears in individuals with a different type of psoriasis that is not well-controlled and can result in serious complications.

Symptoms of psoriasis
While the symptoms of this condition may vary from person to person, some overarching commonalities exist among them. These include the appearance of thick, red skin with silvery-white scales, which tend to itch and burn, causing a lot of discomfort; dry, cracked skin that itches and bleeds; thick, ridged, or pitted nails; and declining quality of sleep.

The type and severity of psoriasis can be determined by the location and type of one’s rash. Instead of looking at pictures of plaque psoriasis or other forms of psoriasis online, visiting a physician or expert for a formal diagnosis is recommended.