Pustular parakeratosis (Hjorth-Sabouraud syndrome) is a condition in which a patient, usually a young girl, has a deformed fingernail or toenail. The affected nail is surrounded by red, often scaly skin. In addition, other nail abnormalities are evident in this underreported condition with no known cause. The treatment involves medication and applying moisturizer. The symptoms of pustular parakeratosis often disappear as the child ages without leaving scars, making the prognosis good.

• Epidemiology of nail disease
• Causes of pustular parakeratosis
• Symptoms: Deformed fingernail with red, scaly skin
• Diagnosis and examinations
• Therapy
• Prognosis

Epidemiology of nail disease

The nail disorder mainly affects children under five years old. Girls are three times more likely than boys to be affected by pustular parakeratosis. The prevalence is unknown as of October 2020 because the condition is insufficiently described in the medical literature. In addition, the doctor often makes no diagnosis or makes an incorrect diagnosis, resulting in the condition being underdiagnosed.

Causes of pustular parakeratosis

The cause of parakeratosis pustulosa is unclear in October 2020. Genetic factors may play a role in the development of the nail abnormality. The disease is often associated with psoriasis, a form of eczema or onychomycosis (fungal nail). Thumb sucking is also a possible trigger for the condition.

Symptoms: Deformed fingernail with red, scaly skin

The thumbnail or index fingernail is usually affected, but it is also possible that another fingernail is affected. Sometimes a toenail is also affected.The onset of the nail abnormality is insidious. First, red skin appears under the free edge of the thumb or index finger. The redness then extends to the nail fold, causing swelling and ultimately loss of the cuticle (keratinized layer of skin on the nail wall). Thickened skin (keratosis) pushes the nail plate upwards and then causes deformation. As a result, a patient’s nail is deformed. An itchy nail does not occur, but nail pain is a possibility.The following signs may also occur:

• blisters on the fingertips
• transverse ridges on the nails
• a red, scaly skin around the nail
• torn or absent cuticles
• onycholysis (detachment of the nail plate from the nail bed)
• onychomadesis (shedding of the nail plate)
• pitting (pitted nails)
• subungual hyperkeratosis (skin thickening under the distal edge of the nail)

Diagnosis and examinations

Differential diagnosis

The symptoms are very variable and sometimes also indicate other skin conditions with a similar clinical picture, such as other psoriasis (chronic skin disease with dry skin and flakes) and atopic dermatitis (atopic eczema: skin disease with itching). Other conditions with similar nail appearance include tinea pedis (athlete’s foot) and tinea unguium (fungal nail), paronychia (inflammation of the nail wall), Hallopeau’s acrodermatitis continua (inflammatory disease with pustules on fingertips and toe tips) and other forms of hand dermatitis.

Diagnostic research

Pustular parakeratosis is a clinical diagnosis, so the doctor must first rule out other skin and nail conditions to be sure of the diagnosis. He therefore takes some swabs to culture microorganisms associated with paronychia, such as Staphylococcus aureus (staphylococcal bacteria), Streptococcus pyogenes (streptococcal bacteria), Pseudomonas species, Proteus species, anaerobes or Candida albicans . Skin scrapings make it possible to rule out a tinea infection. Furthermore, a biopsy is necessary to distinguish atopic dermatitis and psoriasis from parakeratosis pustulosa, but the doctor rarely performs this examination.Moisturizers are useful / Source: Kiyok, Wikimedia Commons (CC BY-SA-3.0)

Therapy

There is no proven effective treatment for pustular parakeratosis as of October 2020. The patient should stop thumb sucking if he does so. Moisturizing creams also relieve complaints. The doctor may also use medications to reduce symptoms such as strong topical steroids, topical (applied to the skin) retinoids and Calcipotriol/calcipotriene.

Prognosis

The nail condition usually improves over time as the child continues to grow. Relapses are rare. Scarring does not occur. Some affected children do develop psoriasis later.

read more

• Nail abnormalities: Common changes to nails
• Nails: Changes in color, strength and texture