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Disease Profile

Subcorneal pustular dermatosis

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Sneddon-Wilkinson disease; Sneddon Wilkinson disease; Pustulosis subcornealis;


Skin Diseases


Subcorneal pustular dermatosis (SPD) is a rare skin disease in which pus-filled pimples or blisters (pustules) form under the top (subcorneal) layer of the skin.[1][2][3][4][5] It is most common in middle-aged adults (particularly women) but can develop in children.[2][5] Pustules usually appear over a few hours and grow together to form round or wavy patterns.[2][3] They most often form in areas where the skin may touch or rub together, such as the groin area, underarms, inside the elbows, and behind the knees.[2][3] The pustules may be mildly itchy or painful, but despite being pus filled, are not infected.[2] The diagnosis of SPD is made based on the appearance of the pustules and the results of a skin biopsy (histologic findings).[2][3] The cause of SPD is not known.[2] There is currently no evidence it is inherited (no familial cases have been reported) and it is not contagious.[1][2] SPD may be associated with other diseases or health problems including several autoimmune diseases, blood (hematologic) diseases, infections, and cancers. Rarely, it has been associated with taking certain medications (drug-induced SPD).[2] SPD may be treated with is oral dapsone, which often improves symptoms within one month. However, the pustules may return when treatment is stopped.[2][4] Other therapies have been tried with mixed results.[2] While SPD may cause discomfort and cosmetic concerns, it typically does not affect overall health.[3]


The main symptom of subcorneal pustular dermatosis (SPD) is an outbreak of round bumps on the skin that may resemble pus-filled pimples or blisters (pustules).[1][2] The pustules appear over a short period of time (hours), usually on healthy skin, but sometimes on skin that is irritated or inflamed.[2][4] Most commonly the outbreak appears in areas of the body where skin may touch or rub together through movement, including the groin area, under women's breasts, underarms, inside the elbows and behind the knees. Other areas of the trunk, the upper arms and upper legs may be affected. [2][3][4] Pustules rarely form on the palms of the hands or soles of the feet, and the face is almost never affected.[2][4] The pustules initially appear separated from each other (isolated) or be grouped together in small clusters, but may spread and join together within one or two days, forming circular, ring-shaped (faded in the center), or wavy patterns on the skin.[1][2][3][5] The pustules have an unusual appearance because the pus tends to settle in the lower half of the blister leaving the upper half of the blister clear (known as hypopyon pustules).[1][2] 

The pustules sometimes cause irritation, pain, or mild itching.[2][3] They break open easily and crust over before healing, sometimes leaving behind darkened spots on the skin (hyperpigmentation). The pustules typically do not cause scarring.[2][4] SPD usually affects the skin only, but some people may have generalized (systemic) symptoms such as a general feeling of being sick (malaise), fever, or joint pain.[2] Additional symptoms may suggest other associated diseases or health problems may be present. [2][3][4]

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Hyperpigmentation of the skin
Patchy darkened skin
30%-79% of people have these symptoms
Itchy skin
Skin itching

[ more ]

5%-29% of people have these symptoms
Overactive thyroid
Underactive thyroid
Increased circulating antibody level
Multiple myeloma
Rheumatoid arthritis
Systemic lupus erythematosus


The reason that a person develops subcorneal pustular dermatosis (SPD) is not known.[2] The pustules are thought to result from a signal pulling (recruiting) neutrophils to the affected areas of skin. Neutrophils are a type of white blood cell (WBC). Skin disorders that involve an abnormal recruitment of neutrophils are called neutrophilic dermatoses (NDs). While there are known triggers of neutrophil recruitment for some NDS, no specific triggers have been found to cause the pustule formation in SPD. An exception is rare cases associated with the use of certain medications.[2][5]

SPD has been associated in case reports with a number of diseases that affect other parts or systems of the body, including but not limited to:[2][3][4]

Autoimmune diseases such as rheumatoid arthritis, lupus, and Sjogren syndrome.
Hematologic diseases or cancers such as monoclonal gammopathies and multiple myeloma.
Infections such as urinary tract infections and respiratory tract infections.

Rarely, SPD has developed in association with taking certain medications (drug-induced SPD).[2]


There are currently no official diagnostic criteria for subcorneal pustular dermatosis (SPD). The disease is diagnosed based on the appearance of the pustules, a skin biopsy which identifies certain characteristics when examined under the microscope (histologic findings), and ruling out other diseases that cause similar pustules.[3] There are no blood tests that can confirm a diagnosis of SPD.[3] Pustular psoriasis can be difficult to distinguish from SPD, and some people initially diagnosed with SPD have later been found to have pustular psoriasis.[3] Identifying a family history of psoriasis may influence whether one or the other is diagnosed.[5] Some cases of SPD have been considered a variant of pustular psoriasis.[5] At this time, the exact relationship between SPD and pustular psoriasis is not understood.[2][3][4][5]


The main goals of treatment for subcorneal pustular dermatosis (SPD) are to minimize discomfort and improve quality of life.[3] Treatment usually begins with oral dapsone, which often clears the pustules within one month.[2][3] Although there have not been randomized clinical trials studying its use for SPD, clinical experience has suggested oral dapsone is effective and well-tolerated.[3] When treatment with dapsone is stopped, the pustules may return, so continued therapy at a lower dose may be recommended to prevent recurrence.[2] Other treatments have been tried with variable success, and data on their use are limited to reports of individual cases. These treatments are generally only tried when dapsone is not effective or not well-tolerated.[3] Possible treatment options include topical or oral corticosteroids, oral retinoids, phototherapy, immunosuppressive oral therapies, and biologic agents.[2][3] In some cases, a combination of therapies may be used. Since SPD does not cause serious health issues, it is important to consider the possible side effects of treatment options.[3]


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Social Networking Websites

    Organizations Providing General Support

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

      • The British Association of Dermatologists has a patient information leaflet about Subcorneal pustular dermatosis.
      • DermNet New Zealand is an online resource about skin diseases developed by the New Zealand Dermatological Society Incorporated. DermNet NZ provides information about this condition.

        In-Depth Information

        • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.


          1. Subcorneal pustular dermatosis (Sneddon-Wilkinson disease). British Association of Dermatologists. January, 2017; https://www.bad.org.uk/shared/get-file.ashx?id=236&itemtype=document.
          2. Watts PJ, Khachemoune A. Subcorneal Pustular Dermatosis: A Review of 30 Years of Progress. Am J Clin Dermatol. December, 2016; 17(6):653-671. https://www.ncbi.nlm.nih.gov/pubmed/27349653.
          3. Kourosh AS. Subcorneal pustular dermatosis. UpToDate. August 21, 2018; https://www.uptodate.com/contents/subcorneal-pustular-dermatosis.
          4. Cheng S, Edmonds E, Ben-Gashir M, Yu RC. Subcorneal pustular dermatosis: 50 years on. Clin Exp Dermatol. May 2008; 33(3):229-233. https://www.ncbi.nlm.nih.gov/pubmed/18355359.
          5. Sekulovic LK. Subcorneal Pustular Dermatosis. Medscape Reference. Sept 22, 2016; https://emedicine.medscape.com/article/1124252-overview.
          6. H.R. 4013 107th Congress: Rare Diseases Act of 2002. GovTrack.us. https://www.govtrack.us/congress/bills/107/hr4013. Accessed 9/12/2018.

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