What are the other Names for this Condition? (Also known as/Synonyms)

• Pustulosis Subcornealis
• Sneddon Wilkinson Disease
• SPD (Subcorneal Pustular Dermatosis)

What is Subcorneal Pustular Dermatosis? (Definition/Background Information)

• Subcorneal Pustular Dermatosis (SPD) is an uncommon and benign skin condition, mostly affecting middle-aged women. It is marked by several pus-filled lesions within red patches on the skin folds of the body (such as the underarms and groin). The condition is also known as Sneddon-Wilkinson Disease
• Since the lesions form below the top layer of skin, the term “subcorneal” is used. The lesions may appear within a short time period (often within hours) and then disappear within a few days; this process may repeat over many years. Subcorneal Pustular Dermatosis may be confused with generalized pustular psoriasis
• Subcorneal Pustular Dermatosis can be adequately treated using medications along-with long-term follow-ups, and the prognosis may be improved. Even though the condition follows a relapsing and remitting course, no severe systemic complications are noted

Who gets Subcorneal Pustular Dermatosis? (Age and Sex Distribution)

• Subcorneal Pustular Dermatosis are generally observed in adults over the age of 40 years, although less commonly children may also be affected
• Both males and females are affected. However, most of the cases are reported in women (woman-man ratio is 4:1)
• Worldwide, there is no racial or ethnic preference observed

What are the Risk Factors for Subcorneal Pustular Dermatosis? (Predisposing Factors)

• Currently, no risk factors for Subcorneal Pustular Dermatosis have been clearly identified
• No family history of the condition is also noted
• In very rare cases, the administration of certain medications may trigger SPD

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Subcorneal Pustular Dermatosis? (Etiology)

The exact cause of formation of Subcorneal Pustular Dermatosis (SPD) is not well-established. It is not known to be caused by an infection or a malignancy.

The condition may be associated with several other diseases and disorders such as:

• Autoimmune conditions such as Sjogren syndrome, systemic lupus erythematosus (SLE), thyroid disease, and rheumatoid arthritis (RA)
• Pyoderma gangrenosum (a skin condition)
• Infections of the respiratory tract and urinary tract
• Blood disorders such as IgA monoclonal gammopathy, multiple myeloma (a form of white blood cell cancer), and polycythemia vera
• Other associations include synovitis-acne-pustulosis-hyperostosis-osteitis (SAPHO) syndrome and inflammatory bowel disease (IBD)

Subcorneal Pustular Dermatosis is not contagious, and it does not spread from one individual to another via direct or indirect physical contact.

What are the Signs and Symptoms of Subcorneal Pustular Dermatosis?

The signs and symptoms of Subcorneal Pustular Dermatosis may include:

• Appearance of small and large pustules (pus-filled blisters) frequently on the skin folds of the body, where skin rub each other, such as the armpits, inside the elbows, beneath breasts, groin region, and behind the knees
• The lesions may however appear on any part of the body (on flat skin surfaces too); they are often confined within a red patchy area on skin
• In rare cases, the pustules may form on the soles of the feet and palms of the hands
• The lesions may be slightly itchy, painful, and cause irritation
• Scattered pustules that form initially may group together to form a ring or wavy pattern
• The pustular lesions appear in crops just below the skin surface; the lesions may appear within a few hours, progress in size (flare-up), and then disappear within the next few days
• Large pustules may rupture with crust formation, which then heal generally without scarring. In some cases, darkened spots may be visible at the site of the lesions
• Scale formation is noted at the site of the skin lesions as they disappear
• Following this the process repeats, and new and fresh pustules form at the location after many months and years

Some individuals may additionally present a feeling of illness (malaise), joint pain, and fever.

How is Subcorneal Pustular Dermatosis Diagnosed?

A diagnosis of Subcorneal Pustular Dermatosis may involve the following exams and procedures:

• Physical examination of the individual and detailed medical history evaluation
• Lab tests, such as complete blood count and blood calcium levels, analysis of pus, culture of the fluid being drained, as needed, to rule out infections
• Protein electrophoresis test
• Liver function test
• Investigative studies to check for any associated condition
• Dermoscopy: Dermoscopy is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• Skin biopsy: A skin biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis

A differential diagnosis may be necessary to eliminate other conditions that present similar signs and symptoms such as:

• Acute generalized exanthematous pustulosis (AGEP)
• Generalized pustular psoriasis (GPP)

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Subcorneal Pustular Dermatosis?

The possible complications due to Subcorneal Pustular Dermatosis include:

• Emotional stress due to cosmetic issues and chronic nature of the condition
• Superimposed bacterial and fungal skin infections
• Decreased quality of life
• Treatment complications
• Complications may arise from the associated conditions (if any noted)

How is Subcorneal Pustular Dermatosis Treated?

Presently, there is no cure available for Subcorneal Pustular Dermatosis (SPD). The treatment measures available help in addressing the signs and symptoms and preventing any complications. The use of medications are known to be effective in controlling symptoms of the condition.

• Use of dapsone (for a period of few weeks) forms the mainstay of treatment. Dapsone is a sulfone class antibiotic. It is used in SPD not because of its antibacterial properties, but because of a fortunate side effect of altering neutrophil-based inflammatory responses
• Continued low-dose treatment with dapsone after resolution of the condition can help prevent recurrences
• Additionally, topical steroid creams may be applied. Systemic steroids may cause flaring up of the condition and are generally avoided
• Medications such as Acitretin, Colchicine, and sulfonamide antibiotic therapy
• UVB and PUVA phototherapy
• Administration of oral immunosuppressants and biologic agents (such as infliximab and adalimumab)
• Undertaking treatment of the associated condition appropriately

Regular (long-term) follow up visits with the healthcare provider is important and highly recommended.

How can Subcorneal Pustular Dermatosis be Prevented?

Presently, there are no available methods or guidelines to prevent the occurrence of Subcorneal Pustular Dermatosis.

What is the Prognosis of Subcorneal Pustular Dermatosis? (Outcomes/Resolutions)

• The prognosis of Subcorneal Pustular Dermatosis may vary from one individual to another and is dependent on its severity and the underlying associated condition
• With proper and sustained treatment (medication), the skin condition is known to regress and improve. However, in many, the condition relapses and remits over many years
• Even though SPD may be chronic, it is not known to cause any significant (systemic) symptoms or complications

Additional and Relevant Useful Information for Subcorneal Pustular Dermatosis:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/