Recurrent Palmoplantar Hidradenitis

Recurrent palmoplantar hidradenitis (RPH) is a chronic skin condition that affects the palms of the hands and soles of the feet. It is characterized by recurrent, painful, and sometimes disfiguring lesions that occur in the sweat glands and hair follicles of these areas. The condition is also known as Hurley’s disease, after the physician who first described it in 1979.

RPH is a rare disorder, with an estimated prevalence of less than 1% of the general population. It is more commonly seen in women than men, and usually develops between the ages of 20 and 50. The exact cause of RPH is not fully understood, but it is believed to be related to a combination of genetic and environmental factors.

There are three stages of RPH, known as Hurley stages. Stage 1 is characterized by single or multiple abscesses, nodules, or both, without sinus tracts or scarring. Stage 2 is characterized by recurrent abscesses, nodules, and sinus tracts, with limited scarring. Stage 3 is characterized by diffuse involvement, with multiple interconnected sinus tracts, extensive scarring, and often, the formation of large, deep, irregular ulcers.

RPH can have a significant impact on quality of life, causing pain, discomfort, and embarrassment, as well as limiting physical activities and causing psychological distress. Treatment options for RPH include topical and systemic medications, as well as surgery.

Types of Recurrent Palmoplantar Hidradenitis:

Primary RPH:

Primary RPH refers to cases in which the condition occurs without any underlying cause or associated medical condition. This is also known as idiopathic RPH. The exact cause of primary RPH is not fully understood, but it is believed to be related to a combination of genetic and environmental factors. This type of RPH is more common in women than men and is typically diagnosed in young to middle-aged adults.

Secondary RPH:

Secondary RPH refers to cases in which the condition is caused by an underlying medical condition or medication. The medical conditions that can cause secondary RPH include inflammatory bowel disease, arthritis, acne, and diabetes. Medications that can cause RPH include corticosteroids, lithium, and antiepileptic drugs. This type of RPH is less common than primary RPH and can occur at any age.

Familial RPH:

Familial RPH is a rare type of RPH that runs in families. It is caused by genetic mutations that affect the immune system and the skin’s ability to heal properly. This type of RPH is usually more severe than other types and can occur at a younger age. The condition may be inherited in an autosomal dominant pattern, which means that only one copy of the mutated gene is necessary to develop the condition.

Punctate Palmoplantar Keratoderma with RPH:

Punctate palmoplantar keratoderma with RPH is a rare genetic disorder that affects the skin and nails of the palms and soles. It is caused by mutations in the AAGAB gene, which plays a role in the formation of sweat glands and hair follicles. The condition is characterized by small, hard, round or oval, keratin-filled papules on the palms and soles, as well as the development of RPH. This type of RPH is usually more severe than other types and can occur at a younger age.

Syndromic RPH:

Syndromic RPH refers to cases in which RPH is associated with other medical conditions or syndromes. The medical conditions that can cause syndromic RPH include Dowling-Degos disease, PASH syndrome

Causes

The exact cause of RPH is not known, but there are several factors that have been identified as potential triggers for the condition. In this article, we will discuss the main causes of RPH in detail.

Genetics:

Genetic factors play a significant role in the development of RPH. The condition is known to run in families, and several genetic mutations have been identified that increase the risk of developing the condition. These mutations affect the immune system, which can lead to inflammation and damage to the sweat glands. Some of the genetic mutations that have been linked to RPH include mutations in the NOD2, CARD15, and PSTPIP1 genes.

Autoimmune disorders:

Autoimmune disorders are conditions in which the immune system attacks the body’s own tissues and organs. Several autoimmune disorders have been linked to RPH, including rheumatoid arthritis, psoriasis, and inflammatory bowel disease. These conditions are characterized by chronic inflammation, which can damage the sweat glands and lead to the development of RPH.

Hormonal imbalances:

Hormonal imbalances can also contribute to the development of RPH. Hormones play a significant role in the regulation of the sweat glands, and imbalances can lead to overactivity or underactivity of these glands. In women, hormonal changes during menstruation, pregnancy, and menopause can trigger RPH.

Bacterial infections:

Bacterial infections can also contribute to the development of RPH. The condition is often associated with infections caused by Staphylococcus aureus, a common type of bacteria that is found on the skin. These infections can cause inflammation and damage to the sweat glands, which can lead to the development of RPH.

Environmental factors:

Environmental factors, such as exposure to chemicals and toxins, can also contribute to the development of RPH. People who work in jobs that require them to handle chemicals or solvents are at an increased risk of developing the condition. Exposure to certain metals, such as nickel and cobalt, has also been linked to RPH.

Obesity:

Obesity is a significant risk factor for RPH. People who are overweight or obese are more likely to develop the condition, and the severity of the symptoms is often worse in these individuals. Obesity can lead to increased sweating and friction in the affected areas, which can contribute to the development of RPH.

Smoking:

Smoking is another risk factor for RPH. People who smoke are more likely to develop the condition, and the severity of the symptoms is often worse in smokers. Smoking can damage the blood vessels and reduce blood flow to the affected areas, which can contribute to the development of RPH.

Stress:

Stress can also contribute to the development of RPH. Chronic stress can weaken the immune system, which can lead to inflammation and damage to the sweat glands. Stress can also lead to increased sweating, which can exacerbate the symptoms of RPH.

Medications:

Certain medications can also contribute to the development of RPH. Medications that suppress the immune system, such as corticosteroids, can increase the risk of developing the condition. Other medications, such as lithium and antiseizure drugs, have also been linked to RPH.

Unknown factors:

Finally, there are several unknown factors that may contribute to the development of RPH. The condition is still not well understood, and more research is needed to identify these factors.

Symptoms

The symptoms of RPH can vary in severity from person to person and may include the following:

Painful nodules: The most common symptom of RPH is the formation of painful nodules or lumps in the palmoplantar area. These nodules can vary in size from a few millimeters to several centimeters and can be tender to the touch.
Abscesses: In some cases, the nodules may progress to form abscesses, which are collections of pus under the skin. Abscesses can be very painful and may require drainage by a healthcare professional.
Sinuses: Over time, the abscesses may form channels or sinuses that connect to the skin’s surface. These sinuses can be difficult to heal and can result in the formation of scars.
Hyperkeratosis: RPH can also cause hyperkeratosis, which is the thickening of the skin on the palms and soles. This can result in a rough, scaly texture and may cause discomfort when walking or using the hands.
Pustules: Another common symptom of RPH is the formation of pustules, which are small, pus-filled bumps on the skin. These pustules can be itchy and can rupture, leading to the formation of crusts and scales.
Pain: RPH can cause significant pain, especially when the nodules and abscesses are present. The pain may be intermittent or constant and can be worsened by pressure or movement.
Swelling: The affected area may become swollen and tender to the touch, especially during periods of flare-up.
Discharge: In some cases, RPH may cause a foul-smelling discharge from the sinuses or abscesses.
Secondary infections: RPH can make the affected area more susceptible to secondary bacterial or fungal infections, which can further complicate the condition.

Diagnosis

The diagnosis of RPH is based on clinical presentation, and additional tests may be required to rule out other conditions that can mimic RPH. In this article, we will discuss the main list of diagnosis and tests for RPH in detail.

Clinical Examination: The diagnosis of RPH is primarily based on clinical examination. The dermatologist will examine the affected areas, including the palms and soles, looking for painful, inflamed nodules or abscesses. The doctor will also assess the extent of the disease and look for signs of scarring or sinus tracts. A thorough physical examination is essential to distinguish RPH from other similar conditions such as bacterial infections, fungal infections, or psoriasis.
Dermoscopy: Dermoscopy is a non-invasive imaging technique that can be useful in the diagnosis of RPH. It involves the use of a handheld device that magnifies the skin surface, allowing for visualization of the underlying structures. In RPH, dermoscopy may reveal a characteristic pattern of white dots, red dots, and hairpin vessels. This pattern is thought to be related to the presence of fibrosis and chronic inflammation in the affected areas.
Ultrasound: Ultrasound is a non-invasive imaging technique that can be used to visualize the internal structures of the skin. In RPH, ultrasound may reveal thickening of the epidermis, subcutaneous tissue, and fascia. It may also show the presence of fluid-filled cavities, abscesses, and sinus tracts. Ultrasound is a useful tool for guiding needle aspiration and drainage procedures.
Magnetic Resonance Imaging (MRI): MRI is a more sophisticated imaging technique that can provide detailed information about the soft tissues of the body. In RPH, MRI may reveal the presence of subcutaneous nodules, abscesses, and sinus tracts. It may also show evidence of inflammation, edema, and fibrosis in the affected areas. MRI is particularly useful in cases where ultrasound is inconclusive or in cases where there is suspicion of deeper involvement of the underlying structures.
Histopathological Examination: Histopathological examination involves the examination of tissue samples under a microscope to identify any abnormalities. In RPH, biopsy samples may reveal a characteristic pattern of follicular plugging, hyperkeratosis, and chronic inflammation. There may also be evidence of abscess formation and fibrosis. Histopathological examination is an important tool for confirming the diagnosis of RPH and ruling out other conditions that may mimic the disease.
Culture and Sensitivity Testing: Culture and sensitivity testing involves the collection of samples from the affected areas for laboratory analysis. This can help to identify the causative organisms and determine the most appropriate course of treatment. In RPH, culture and sensitivity testing may reveal the presence of Staphylococcus aureus or other bacteria. This information can be used to guide antibiotic therapy.
Genetic Testing: In some cases, RPH may be associated with genetic mutations that predispose individuals to the disease. Genetic testing can be used to identify these mutations and provide information about the risk of disease recurrence in affected individuals and their family members. However, genetic testing is not routinely performed in the diagnosis of RPH, and its utility in clinical practice is still being evaluated.
Biopsy: A skin biopsy may be required to confirm the diagnosis of RPH. During the procedure, the dermatologist will remove a small piece of skin tissue from the affected area and send it to the laboratory for analysis. The biopsy can help rule out other skin conditions and confirm the presence of RPH. Histological examination of the biopsy can show characteristic features of the disease, such as the presence of abscesses or granulomas.
Microbiology Tests: Since RPH can mimic bacterial infections, microbiology tests may be required to rule out a bacterial infection. The dermatologist may take a sample of the pus or drainage from the affected area and send it for culture and sensitivity testing. The test can identify the type of bacteria responsible for the infection and determine which antibiotics are most effective against it.
Imaging Tests: Imaging tests such as ultrasound, MRI, or CT scans may be necessary to evaluate the extent of the disease and identify any complications. These tests can help the dermatologist to determine if there are any sinus tracts or fistulas and if the condition has spread to other areas. Imaging tests can also help rule out other conditions that can mimic RPH, such as tumors or foreign bodies.
Blood Tests: Blood tests may be required to rule out other systemic conditions that can mimic RPH, such as autoimmune diseases or infections. Blood tests can help the dermatologist to evaluate the patient’s overall health, check for signs of inflammation or infection, and monitor the response to treatment. Blood tests may include a complete blood count, erythrocyte sedimentation rate, C-reactive protein, and autoimmune panel.
Allergy Tests: Allergy tests may be required to rule out an allergic reaction as the cause of RPH. The dermatologist may perform patch tests to identify any contact allergens that may be triggering the disease. Allergy tests can also help identify any environmental or dietary triggers that may be exacerbating the condition.
Sweat Testing: Sweat testing may be required to evaluate the function of sweat glands in the affected areas. The dermatologist may perform a sweat test using the iodine-starch test or the pilocarpine iontophoresis test. Sweat testing can help determine if the sweat glands are blocked or damaged and may help guide treatment decisions.

Treatment

The treatment of RPH is complex and requires a multidisciplinary approach. The main goals of treatment are to reduce inflammation, prevent scarring and fibrosis, and improve the patient’s quality of life. There are several treatment options available for RPH, including medical, surgical, and lifestyle modifications. In this article, we will discuss the main treatments for RPH in detail.

Topical treatments

Topical treatments are medications that are applied directly to the affected area of the skin. They are often the first line of treatment for RPH because they are non-invasive and can be easily applied at home. Topical treatments for RPH include:

Topical antibiotics: Topical antibiotics, such as clindamycin and erythromycin, can help to reduce inflammation and prevent bacterial infection in the affected area. They are often used in combination with other treatments.
Retinoids: Retinoids, such as tretinoin and adapalene, are vitamin A derivatives that can help to reduce inflammation and improve skin cell turnover. They are often used to treat acne, but can also be effective in managing RPH.
Corticosteroids: Corticosteroids, such as hydrocortisone and betamethasone, can help to reduce inflammation and itching in the affected area. They are often used for short-term relief of symptoms.
Dapsone: Dapsone is an antibiotic that can help to reduce inflammation and prevent bacterial infection in the affected area. It is often used in combination with other treatments.

Medical treatments:

Topical agents: The first-line treatment for RPH is topical agents, which are applied directly to the affected area. The most commonly used topical agents are corticosteroids, which reduce inflammation and promote healing. Other topical agents used to treat RPH include retinoids, antibiotics, and antiseptics. Topical agents are generally safe and well-tolerated, but they may not be effective in severe cases of RPH.
Systemic agents: In cases where topical agents are not effective, systemic agents may be used. Systemic agents are medications that are taken orally or injected. The most commonly used systemic agents for RPH are antibiotics, such as tetracyclines, macrolides, and clindamycin. Antibiotics work by reducing bacterial colonization, which can trigger inflammation in RPH. Other systemic agents used to treat RPH include immunosuppressants, such as cyclosporine and methotrexate, which reduce inflammation by suppressing the immune system.
Biologic agents: Biologic agents are a relatively new class of medications that target specific molecules involved in inflammation. Biologic agents used to treat RPH include tumor necrosis factor (TNF) inhibitors, such as adalimumab and infliximab, and interleukin (IL) inhibitors, such as ustekinumab and secukinumab. Biologic agents are generally reserved for severe cases of RPH that do not respond to other treatments.

Systemic treatments

Systemic treatments are medications that are taken orally or by injection. They are often used for more severe cases of RPH that do not respond to topical treatments. Systemic treatments for RPH include:

Antibiotics: Antibiotics, such as tetracycline and doxycycline, can help to reduce inflammation and prevent bacterial infection in the affected area. They are often used in combination with other treatments.
Immunosuppressive agents: Immunosuppressive agents, such as methotrexate and cyclosporine, can help to reduce inflammation and suppress the immune system. They are often used for severe cases of RPH that do not respond to other treatments.
Biologics: Biologics, such as adalimumab and infliximab, are medications that target specific molecules involved in the inflammatory response. They can help to reduce inflammation and improve symptoms in some people with RPH.
Retinoids: Oral retinoids, such as isotretinoin, can help to reduce inflammation and improve skin cell turnover. They are often used to treat acne, but can also be effective in managing RPH.

Surgical treatments:

Incision and drainage: Incision and drainage is a minor surgical procedure that involves making an incision in the affected area and draining the pus. This procedure is typically performed under local anesthesia and can provide immediate relief from pain and swelling. However, incision and drainage does not prevent the recurrence of RPH, and multiple procedures may be necessary.
Excision: Excision is a more aggressive surgical procedure that involves removing the affected area of skin and underlying tissue. This procedure is typically reserved for severe cases of RPH that do not respond to other treatments. Excision can be effective in reducing inflammation and preventing recurrence, but it can also result in scarring and functional impairment.
Laser therapy: Laser therapy is a non-invasive treatment that uses a laser to destroy the affected tissue. Laser therapy can be effective in reducing inflammation and preventing the recurrence of RPH, but it can also result in scarring and hyperpigmentation.
Incision and drainage: Incision and drainage involve making a small incision in the abscess to drain pus and relieve pressure. This can provide immediate relief of symptoms but does not treat the underlying condition.
Excision: Excision involves removing the affected tissue, including the sweat glands. This can be an effective treatment for severe cases of RPH, but can also lead to scarring and disfigurement.
Mohs micrographic surgery: Mohs micrographic surgery is a specialized technique that involves removing the affected tissue layer by layer and examining it under a microscope to ensure

Lifestyle modifications:

Weight loss: Obesity is a risk factor for RPH, and weight loss can help reduce the severity and frequency of flare-ups. Weight loss can also improve the patient’s overall health and quality of life.
Smoking cessation: Smoking is a risk factor for RPH, and smoking cessation can help reduce the severity and frequency of flare-ups. Smoking cessation can also improve the patient’s overall health and quality of life.
Wound care: Proper wound care can help prevent infection and promote healing.

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