Pityriasis

Pityriasis comes from Greek word bran and is used to describe flaky scaly skin. There are a few types of pityriasis skin conditions namely Pityriasis Alba, Pityriasis Lichenoides, Pityriasis Rosea, Pityriasis Rubra  Pilaris and Pityriasis Versicolor (Tinea Versicolor). The conditions will be described below:

Pityriasis Alba

Pityriasis Alba is a common skin disorder that affects children and young adult. The exact cause is unknown. It first appears as scaly mild red round/oval patches which subsequently lighten to form pale white patches on the skin. It can occur on the face, neck, shoulders and upper limbs. The most common place is still the face. The skin pigmentation will return on its own after months to a year.

Dry skin or cold weather may be contributing factor. It is not contagious. Diagnosis is by clinical presentation. No laboratory tests are required. Treatment is seldom needed as it usually remits on its own. Mild steroid cream (hydrocortisone) or tacrolimus cream may be used if the skin lesions are itchy. The white patches usually do not re-pigment well with sun exposure so repeated sun exposure should be avoided as it will make the patches more distinct when the surrounding skin darkens.

Pityriasis Lichenoides

Pityriasis Lichenoides is an uncommon condition. The acute form is called pityriasis lichenoides et varioliformis acuta (PLEVA) which is an abrupt outbreak of crusty reddish brown spots and blisters. The longstanding form is called pityriasis lichenoides chronica (PLC) which is gradual formation of small scaly papules which gradually flatten and disappear after weeks without any symptoms.

Pityriasis Lichenoides is an uncommon skin condition more common in males. It usually occurs in young teenagers/adults before age 30. The exact cause is unknown. It is postulated to be triggered by inflammatory processes associated with infections like EBV, Cytomegalovirus, Parvovirus, HIV, Toxoplasma Gondii and group A Beta-Hemolytic streptococci.

Other hypothesis includes benign form of T cell lymphoproliferative disorder (excess T and B cells) and immune-complex mediated hypersensitivity Vasculitis (immune complexes that are deposited in the skin).

Clinical presentation of PLEVA and PLC

PLEVA: It is characterized by acute onset of 10-50 red to brown round itchy bumps on the skin. The skin papules may contain pus and blood. They range from 5-15 mm in diameter and commonly found on the trunks and limbs. The skin lesions can be itchy, painful, burning sensation and get infected.

In severe form, infection can spread to other organs causing fever, sore throat, abdomen pain, diarrhea, lung disease, anemia and conjunctiva ulcers.

PLC: It is a milder form that lasts from weeks to months to years. It can start off as pink bumps which turn reddish brown with a central scaly spot. The bump will slowly flatten leaving a brown scar which will fade with time. Unlike PLEVA, these skin lesions do not cause any symptoms. They can occur commonly on trunk, buttocks, upper and lower limbs.

Investigation is often to identify the associated infections that could have triggered pityriasis lichenoides and inflammatory markers. Punch biopsy of skin lesion will confirm the diagnosis.

Treatment: Pityriasis is associated with relapses and may not respond to treatment. If there is infected wounds/ulcers then oral antibiotics and wound care is necessary. Other treatment options include phototherapy, retinoids, immunosupressants, immunomodulators and possible topical steroids. 

Pityriasis Rosea

Pityriasis Rosea its name implies a “fine pink scale”. This is a common self- limiting non-cancerous skin condition that lasts for 6-8 weeks. It commonly occurs in teenagers and young adults with age onset between 10-35 years old. It occurs slightly more common in women but there is no racial predominance.

Causes: The exact cause is unknown but it is sometimes set off after upper respiratory tract infection (cough, sore throat and flu). The rash itself is not contagious.    

Clinical features: The herald patch which is an oval pink salmon-colored solitary scaly patch is the first lesion to occur about 1-2 weeks. The herald patch will have a central pink color surrounded by darker red peripheral margin. After the appearance of herald patch, it will be followed by the outbreak of red scaly patches/plaques occur on the chest and back. These patches that occur later on appear symmetrically with a collarette scale oriented with their long axes along cleavage lines resembling the fir tree pattern.

The rash is often itchy and may last 6 to 8 weeks. The rash usually found on the trunk, abdomen and back. Following the rash, post inflammatory hypopigmentation and hyperpigmentation may remain a couple of months.

Diagnosis: is made by its clinical picture. Investigations to rule out differential diagnosis of tinea (fungal infection) and syphilis may be done if suspected.

Treatment: Pityriasis Rosea is a self-limiting condition so treatment is mainly supportive. Shower gels/soaps that may irritate the skin is best avoided. Antihistamines can be given to control the itch. Topical zinc oxide, steroids and calamine lotion may also ease the itch and inflammation. Phototherapy maybe effective in persistent and extensive cases but it may leave hyperpigmentation scars. 

Pityriasis Rubra Pilaris

Pityriasis Rubra Pilaris is a rare papulosquamous skin disorder of unknown etiology. The acquired form occurs during the 1st and 5thdecades of life. The familial inherited form occurs during early childhood. The inherited form is autosomal dominant meaning 50% of offspring of affected individual has the disease.  There is no gender predominance.

Clinical presentation: The acquired form has an acute onset of disease whereas the inherited has a gradual onset of disease. The disease usually starts from the head and moves downwards. Redness and scales will first appear on the scalp and face followed by skin thickening and redness of palms and soles.

Multiple patches will then coalesce together to form reddish-orange scaly patches with sharp borders which may further expand to involve the whole body. There may be parts of the body (trunk and limbs) which is uninvolved often known as islands of sparing.

The nails may have yellow-brown discoloration, longitudinal ridging, pitting and splinter hemorrhages. There may be pain in the oral cavity with diffuse white mucosa and erosions. In extensive disease, patients may have ectropion (lower eyelid turns outwards), dry eyes and blurred vision.

Diagnosis: laboratory tests are not required as diagnosis is by clinical findings supported with histological findings found on biopsy. In severe cases where there is severe spread of bacteria, blood tests can be done to monitor the condition.

Treatment: Topical applications include steroids, retinoids, calcipotriol (vitamin d analogue) and moisturizers to reduce dryness and fissuring. Phototherapy may be used if patients do not respond to topical treatments. Oral immunosupressants and monoclonal antibodies that suppress the immune system may benefit some patients with severe condition.

Pityriasis Versicolor

Pityriasis Versicolor is also known as tinea Versicolor which is a common benign skin condition that often affects the chest and back. Pityriasis means “scaly” and Versicolor means “multiple colors. It is characterized by hypopigmented or hyperpigmented flaky scaly skin patches on the body caused by a fungal infection. It commonly occurs in teenagers and young adults with average onset age of 15-24 years old.

Causes: Pityriasis Versicolor is caused by the fungus Malassezia 
Furfur. Malassezia furfur can be found on normal healthy skin. When they grow over actively on the skin that’s when pityriasis Versicolor forms. Predisposing factors include immunosuppressant states, genetic predisposition, warm humid environments, Cushing disease and malnutrition. As it is caused by the fungus which is normally found on skin so it is not infectious or contagious.

Clinical features: The lesions can range from pale color, pink to brown color scaly oval shaped patches. Pale patches are common in darker-skinned people. The lesions are commonly found on the trunk, neck and arms.

Investigations: Pityriasis Versicolor is usually diagnosed clinically. Using Wood’s light (long wave ultraviolet) to examine the lesions will review yellow-green fluorescence. Diagnosis is often confirmed with potassium hydroxide microscopic examination which will reveal fungal spores with mycelium resembling spaghetti and meatballs picture.

Treatment: It is caused by fungus so treatment involves topical antifungal (azole creams and topical selenium sulfide) or oral antifungal (ketoconazole, itraconazole and fluconazole). Despite treatment, recurrence can occur.  

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