Hidradenitis suppurativa


Hidradenitis suppurativa, also known as acne inversa, is a long-term skin disease characterized by the occurrence of inflamed and swollen lumps. These are typically painful and break open, releasing fluid or pus. The areas most commonly affected are the underarms, under the breasts, and groin. Scar tissue remains after healing.
The exact cause is usually unclear but believed to involve a combination of genetic and environmental factors. About a third of people with the disease have an affected family member. Other risk factors include obesity and smoking. The condition is not infectious, related to hygiene, or the use of deodorant. The underlying mechanism is believed to involve either a dysfunction of apocrine sweat glands or hair follicles. Diagnosis is based on the symptoms.
There is no known cure. Warm baths may be tried in those with mild disease. Cutting open the lesions to allow them to drain does not result in significant benefit. While antibiotics are commonly used, evidence for their use is poor. Immunosuppressive medication may also be tried. In those with more severe disease, laser therapy or surgery to remove the affected skin may be carried out. Rarely, a skin lesion may develop into skin cancer.
It is estimated to affect between 1% and 4% of people. Women have the condition about three times more often than men. Onset is typically in young adulthood and may become less common after 50 years old. It was first described some time between 1833 and 1839 by French anatomist Alfred Velpeau.

Causes

The cause of hidradenitis suppurativa remains unknown, and experts disagree over proposed causes. The condition probably results from a combination of genetic and environmental factors.
Lesions occur in any body areas with hair follicles, although areas such as the axilla, groin, and perianal region are more commonly involved. This theory includes most of the following potential indicators:
The historical understanding of the disease suggests dysfunctional apocrine glands or dysfunctional hair follicles, possibly triggered by a blocked gland, which creates inflammation, pain, and a swollen lesion.

Triggering factors

Several triggering factors should be taken into consideration:
Some cases have been found to result from mutations in the NCSTN, PSEN1 or PSENEN genes. The genes produce proteins that are all components of a complex called gamma- secretase. This complex cuts apart many different proteins, which is an important step in several chemical signaling pathways. One of these pathways, known as Notch signaling, is essential for the normal maturation and division of hair follicle cells and other types of skin cells. Notch signaling is also involved in normal immune system function. Studies suggest that mutations in the NCSTN, PSEN1, or PSENEN gene impair Notch signaling in hair follicles. Although little is known about the mechanism, abnormal Notch signaling appears to promote the development of nodules and lead to inflammation in the skin.

Diagnosis

Stages

Hidradenitis suppurativa presents itself in three stages. Due to the large spectrum of clinical severity and the severe impact on quality of life, a reliable method for evaluating HS severity is needed.

Hurley's staging system

The Hurley's staging system was the first classification system proposed, and is still in use for the classification of patients with skin diseases. Hurley separated patients into three groups based largely on the presence and extent of cicatrization and sinuses. It has been used as a basis for clinical trials in the past and is a useful basis to approach therapy for patients. These three stages are based on Hurley's staging system, which is simple and relies on the subjective extent of the diseased tissue the patient has. Hurley's three stages of hidradenitis suppurativa are:
StageCharacteristics
ISolitary or multiple isolated abscess formation without scarring or sinus tracts.
IIRecurrent abscesses, single or multiple widely separated lesions, with sinus tract formation.
IIIDiffuse or broad involvement across a regional area with multiple interconnected sinus tracts and abscesses

Sartorius staging system

The Sartorius staging system is more sophisticated than Hurley's. Sartorius et al. suggested that the Hurley system is not sophisticated enough to assess treatment effects in clinical trials during research. This classification allows for better dynamic monitoring of the disease severity in individual patients. The elements of this staging system are:
Points are accumulated in each of the above categories, and added to give both a regional and total score. In addition, the authors recommend adding a visual analog scale for pain or using the dermatology life quality index when assessing HS.

Treatment

Treatment depends upon presentation and severity of the disease. Due to the poorly studied nature of the disease, the effectiveness of the drugs and therapies listed below is unclear. Possible treatments include the following:

Lifestyle

Warm baths may be tried in those with mild disease. Weight loss and stopping smoking is also recommended.

Medication

When the process becomes chronic, wide surgical excision is the procedure of choice. Wounds in the affected area do not heal by secondary intention, and immediate or delayed application of a split-thickness skin graft is an option.
Another option is covering the defect with a so-called perforator flap. With this technique the defect is covered with living tissue 'stolen' from the area nearby. For example, the axilla with a fully excised defect of 15 × 7 cm can be covered with a so-called TAP flap

Laser hair removal

The 1064 nanometer wavelength laser for hair removal may aid in the treatment of HS. A randomized control study has shown improvement in HS lesions with the use of an.

Prognosis

In stage III disease, as classified by the Hurley's staging system, fistulae left undiscovered, undiagnosed, or untreated, can rarely lead to the development of squamous cell carcinoma in the anus or other affected areas. Other stage III chronic sequelae may also include anemia, multilocalized infections, amyloidosis, and arthropathy. Stage III complications have been known to lead to sepsis, but clinical data is still uncertain.

Potential complications

A surgeon from Paris, Velpeau described an unusual inflammatory process with formation of superficial axillary, submammary, and perianal abscesses, in a series of three publications from 1833 to 1839. One of his colleagues also located in Paris, named Verneuil, coined the term hidrosadénite phlegmoneuse about 15 years later. This name for the disease reflects the former pathogenetic model of acne inversa, which is considered inflammation of sweat glands as the primary cause of hidradenitis suppurativa. In 1922, Schiefferdecker suspected a pathogenic association between acne inversa and apocrine sweat glands. In 1956 Pillsbury postulated follicular occlusion as the cause of acne inversa, which they grouped together with acne conglobata and perifolliculitis capitis abscendens et suffodiens as the "acne triad". Plewig and Kligman added another element to their acne triad, pilonidal sinus. Plewig et al. noted that this new "acne tetrad" includes all the elements found in the original "acne triad", in addition to a fourth element, pilonidal sinus. In 1989, Plewig and Steger introduced the term "acne inversa", indicating a follicular source of the disease and replacing older terms such as "Verneuil disease".
AuthorYearFindings
Velpeau1839First description of the hidradenitis suppurativa
Verneuil1854"Hidrosadénite phlegmoneuse"
Pillsbury1956Acne triad
Plewig & Kligman1975Acne tetrad
Plewig & Steger1989Acne inversa

Other names

Hidradenitis suppurativa has been referred to by multiple names in the literature, as well as in various cultures. Some of these are also used to describe different diseases, or specific instances of this disease.
AuthorYearMajor Features
Plewig & Steger1989Initial hyperkeratosis of the follicular infundibulum. Bacterial super-infection and follicle rupture. Granulomatous inflammatory reaction of the connective tissue. Apocrine and eccrine sweat glands secondarily involved.
Yu & Cook1990Cysts and sinus tracts lined with epithelium, in part with hair shafts. Inflammation of apocrine sweat glands only if eccrine sweat glands and hair follicles are also inflamed.
Boer & Weltevreden1996Primary inflammation of the follicular infundibulum. Apocrine sweat glands are secondarily involved.

Terminology

Although hidradenitis suppurativa is often referred to as acne inversa, it is not a form of acne and lacks the core defining features of acne such as the presence of closed comedones and increased sebum production.