Subcorneal pustular dermatosis, initially known as Sneddon-Wilkinson disease, is considered to be a rare cutaneous disorder that belongs to a group of neutrophilic dermatoses [1] [2] [3]. Although the exact etiology remains to be elucidated, skin lesions arise due to an abundant presence of neutrophils below the stratum corneum, presumably as a result of the activity of pro-inflammatory cytokines such as interleukin-8 that act as chemoattractants for neutrophils [2] [4]. For some reason, subcorneal pustular dermatosis is most commonly diagnosed in middle-aged and older women aged 40 or more years [1] [3]. The clinical presentation is characterized by the appearance of sterile pustular lesions on the trunk, the intertriginous areas (the axillae, the submammary areas, and the groins), and the flexor areas of the upper or lower limbs [2] [3] [5] [6] [7] [8]. These pustules are symmetrically distributed and often form blistering lesions [3] [5] [6]. Despite the benign and self-limiting nature of the condition, a chronic course with frequent recurrences are hallmarks of subcorneal pustular dermatosis, which may be debilitating for the patient [1] [3]. Because of the undisclosed cause, the precipitating factors for recurrence are yet to be revealed.

The differential diagnosis of subcorneal pustular dermatosis is broad, encompassing other neutrophilic dermatoses (Sweet's syndrome, acute generalized exanthematous pustulosis, and generalized pustular psoriasis) and systemic conditions that include this cutaneous disorder in the presentation, such as various lymphoproliferative disorders (eg. multiple myeloma) and immunoglobinopathies [1] [2] [3]. For this reason, the identification of subcorneal pustular dermatosis mandates a thorough workup and a histopathological examination. As a first step, however, the physician must obtain a detailed patient history that will identify the chronic and relapsing pattern of the lesions, whereas a physical exam is crucial for observing the pattern of distribution and the appearance of skin lesions. As soon as clinical suspicion is raised, a biopsy sample should be obtained for the purposes of performing a histopathological examination. The hallmark of neutrophilic dermatoses is the presence of a break below the stratum corneum that contains a dense neutrophilic infiltrate with a normal underlying epidermis [1] [5] [7] [8]. Additionally, exclusion of immunoglobinopathies and autoimmune disorders can be made by carrying out an immunofluorescence exam that is virtually always negative [3] [8], although rare cases of immunoglobulin (Ig)A-presenting antibodies in the epidermis were documented, thus pointing toward IgA pemphigus as a potential differential diagnosis [3].

The primary goal of SPD treatment is to reduce symptoms and prevent flare-ups. Dapsone, an antibiotic with anti-inflammatory properties, is often the first-line treatment. Other medications, such as corticosteroids or retinoids, may be used in cases where dapsone is ineffective or not tolerated. Topical treatments, including corticosteroid creams, can help manage localized symptoms. Regular follow-up with a healthcare provider is essential to monitor the condition and adjust treatment as needed.

The prognosis for SPD is generally favorable, as it is a chronic but manageable condition. While SPD can persist for many years, appropriate treatment can significantly reduce symptoms and improve quality of life. Some patients may experience long periods of remission, while others may have recurrent episodes. Continuous medical management is often necessary to keep the condition under control.

The exact cause of SPD is not well understood. It is believed to be an autoimmune disorder, where the body's immune system mistakenly attacks healthy skin cells. Genetic factors may play a role, as SPD sometimes occurs in individuals with a family history of similar skin conditions. Environmental factors, such as stress or infections, may trigger flare-ups in susceptible individuals.

SPD is a rare condition, with a higher incidence in middle-aged women. It is less common in children and men. The exact prevalence is unknown due to its rarity and potential underdiagnosis. SPD can occur in individuals of all ethnic backgrounds, but there is limited data on its distribution across different populations.

In SPD, the immune system targets the skin, leading to the formation of pustules beneath the stratum corneum, the outermost layer of the skin. This results in the accumulation of neutrophils, a type of white blood cell, which form the pus-filled blisters characteristic of the condition. The exact mechanism triggering this immune response is not fully understood, but it is thought to involve a combination of genetic and environmental factors.

There are no specific measures to prevent SPD, given its unclear etiology. However, managing stress and avoiding known triggers, such as certain medications or infections, may help reduce the frequency of flare-ups. Regular follow-up with a healthcare provider can aid in early detection and management of symptoms, potentially minimizing the impact of the condition.

Subcorneal Pustular Dermatosis is a rare, chronic skin condition characterized by pustules beneath the skin's surface. While the exact cause is unknown, it is believed to be an autoimmune disorder. Diagnosis involves clinical evaluation and skin biopsy, and treatment typically includes medications like dapsone. The prognosis is generally good with appropriate management, although the condition can be recurrent. Understanding the condition's presentation and management is crucial for improving patient outcomes.

If you have been diagnosed with Subcorneal Pustular Dermatosis, it's important to understand that while the condition is chronic, it is manageable with the right treatment. You may experience periods of flare-ups and remission, but medications can help control symptoms. Regular check-ups with your healthcare provider are essential to monitor your condition and adjust treatment as needed. Remember, SPD is not contagious, so it cannot be spread to others. Managing stress and avoiding known triggers can also help reduce flare-ups.

1. Abreu-Velez AM, Smith JG, Howard MS. Subcorneal pustular dermatosis an immnohisto-pathological perspective. Int J Clin Exp Pathol. 2011;4(5):526-529.
2. Ono S, Otsuka A, Miyachi Y, Kabashima K. Subcorneal Pustular Dermatosis Exhibiting a High Serum TARC/CCL17 Level. Case Rep Dermatol. 2013;5(1):38-42.
3. Ratnarathorn M, Newman J. Subcorneal pustular dermatosis (Sneddon-Wilkinson disease) occurring in association with nodal marginal zone lymphoma: a case report. Dermatol Online J. 2008;14(8):6.
4. Keller M, Spanou Z, Schaerli P, Britschgi M, Yawalkar N, Seitz M, Villiger PM, Pichler WJ. T cell-regulated neutrophilic inflammation in autoinflammatory diseases. J Immunol. 2005;175:7678–7686.
5. Cheng S, Edmonds E, Ben-Gashir M, Yu RC. Subcorneal pustular dermatosis: 50 years on. Clin Exp Dermatol. 2008;33(3):229-233.
6. Watts PJ, Khachemoune A. Subcorneal Pustular Dermatosis: A Review of 30 Years of Progress. Am J Clin Dermatol. 2016;17(6):653-671.
7. Nischal KC, Khopkar U. An approach to the diagnosis of neutrophilic dermatoses: A histo-pathological perspective. Indian J Dermatol Venereol Leprol. 2007;73:222–230.
8. Kretschmer L, Maul J-T, Hofer T, Navarini AA. Interruption of Sneddon-Wilkinson Subcorneal Pustulation with Infliximab. Case Rep Dermatol. 2017;9(1):140-144.