Ostraceous Psoriasis: Symptoms, Diagnosis, Treatment


Psoriasis is a common skin condition. It causes skin cells to grow and multiply faster than the body can shed them. As a result, excess cells build up, causing plaques or lesions to form.

Plaque psoriasis is the most common form of psoriasis. It usually causes large, oval-shaped plaques to form on the skin. These may be a different color from the surrounding skin and appear scaly. They can appear on a person’s trunk, scalp, and buttocks, as well as other areas.

Ostraceous psoriasis is a rare subtype of plaque psoriasis. The plaques that form are hard and thick, sometimes resembling oyster shells.

Below, we explore ostraceous psoriasis in detail, including its symptoms, treatments, and outlook.

In someone with ostraceous psoriasis, patches of skin shaped like an oyster shell tend to form on the scalp, trunk, buttocks, knees, or elbows.

Ostraceous psoriasis is linked to hyperkeratosis, the thickening of the outer layer of the skin. The outer layer is made up of a protein called keratin. When hyperkeratosis occurs, the keratin in the outer layer begins to grow out of control and thickens.

According to a Study 2020, ostraceous psoriasis has a strong association with psoriatic arthritis. Psoriatic arthritis is a type of inflammatory arthritis that affects approximately 1 of 4 people with psoriasis.

People with both conditions often need additional treatment for psoriatic arthritis.

The skin patches that characterize ostraceous psoriasis are thick and hard.

The authors of a 2015 case report describes these plates in more detail. The inner faces of the plates, they noted, tend to be concave, surrounded by a thickened kinship ring, and covered with thick scales that remain attached to the plate. These authors also described the plates as resembling oyster shells.

Other types of plaque psoriasis tend to cause inflamed, scaly lesions.

The plaques usually appear symmetrically, usually on:

  • torso
  • knees
  • scalp
  • elbows
  • buttocks

Plaque psoriasis can also affect the nails, stinging them or discoloring them. The nails may start to separate from the nail beds.

If a person also develops psoriatic arthritis, some joints may stiffen, swell, and become painful, and symptoms may worsen in the morning. Specifically, the toes and fingers can develop a sausage-like swelling. This is sometimes the first sign of psoriasis.

It may be interesting to note that children can also develop psoriasis and psoriatic arthritis.

Anyone who thinks they have psoriasis should contact a healthcare professional. They may refer the person to a dermatologist, a specialist in skin conditions, who has more experience with psoriasis.

During an evaluation, a dermatologist tends to examine a person’s scalp, nails, and skin. They also usually ask questions about:

  • a family history of the disease
  • joint pain or damage
  • recent changes in stress or illness
  • additional symptoms, including pain and itching

The dermatologist may also remove a piece of skin from the affected area. Examining this sample under a microscope can help confirm a diagnosis of psoriasis.

Treatment for most cases of psoriasis involves reducing the severity of the skin lesions and preventing them from flaring or spreading.

Treatment for ostraceous psoriasis is similar to that for the more common types of plaque psoriasis. According to a to studyeffective treatment may involve taking the immunosuppressive drug cyclosporine and using a topical product that contains both a steroid and an emollient, which softens the skin.

A dermatologist may also recommend:

  • phototherapy
  • oral medications
  • biological drugs, which target the immune system
  • creams, ointments, and other medicated topical products designed to reduce symptoms of psoriasis

Some oral medications for psoriasis include:

In addition, they can recommend strategies to relieve symptoms and reduce the likelihood of psoriasis flare-ups. These self-care techniques can include:

What’s more, research indicates that the balance of bacteria and other microbes in the gut may play a role in psoriasis. The dermatologist may recommend taking a probiotic supplement.

Learn more about the relationship between gut bacteria and psoriasis here.

Psoriasis is a chronic, incurable disease, but treatment and self-care strategies can help reduce symptoms and prevent them from flaring up. This can lead to fair or almost fair skin.

Since ostraceous psoriasis is a rare subtype, specific information is limited. However, some research suggests that the medications and therapies that dermatologists typically prescribe for people with plaque psoriasis may be beneficial for people with this subtype.

People with psoriasis have an increased risk of cardiovascular disease and a doctor may recommend annual monitoring. This may involve a cholesterol profile and an EKG, which records electrical signals from the heart.

Ostraceous psoriasis is a rare subtype of plaque psoriasis. Although the plaques look slightly different from typical psoriasis plaques and may resemble oyster shells, the diagnosis and treatments are similar.

A dermatologist will work with a person to determine the best treatment approach, which can reduce symptoms and help prevent them from coming back.


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