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Acne inversa/ Hidradenitis suppurativa
Approximately 0.5% of the human population is affected by Acne inversa (also called Hidradenitissuppurativa or HS). The onset of this disease usually occurs after puberty and affects those patientsfor several decades. Diagnosis is still a big challenge for most physicians.
Acne inversa is an inflammatory but non-infectious skin disease. Mainly affected areas are armpits,groin, the buttocks, and the regions around the anus and under the female breast. Affected areasoften show deep-seated inflamed nodes, abscesses and pus-secreting fistula passages. Withouttreatment, it results in extensive scarring and restriction of movement in the affected areas.
It is not completely understood why some people develop Acne inversa. Approximately 30% ofpatients exhibit a hereditary predisposition. In addition, factors such as obesity and smoking promotedevelopment of this disease. However, there are Acne inversa patients with normal weight and whodo not smoke.
What we know for sure is that this condition starts at/around the hair follicles, in other words, thestructures that embed and anchor the hair into the skin and in which the sebaceous glands open.
The openings of the hair follicles get plugged, leading to hair follicle dilatation and rupture. Subsequently,inflamed nodes and abscesses evolve. The immune system is a key player in this disease. Immunecells are present in skin that does not yet show any clinical alteration but trigger local inflammationin the affected tissue. The immune cells contained in mature skin lesions include neutrophilicgranulocytes, macrophages, B cells and T cells. Additional immigration of immune cells and pusformation in the skin is supported by the proliferation of bacteria derived from the bacterial flora ofthe skin and mucosa. Present immune cells produce immune substances such as cytokines that affectlocal tissue cells. Then, tissue-degrading enzymes and specific proteins that attracts more immunecells are produced. This loop of disease causes a progressive damage of normal skin structure. The important cytokinesin the skin lesions of Acne inversa patients are TNF-alpha, interleukin-1, interleukin-17, andinterleukin-36. In contrast, the concentration of the T-cell cytokine interleukine-22, which is essentialfor bacterial defense, is rather low.
Impact and accompanying diseases
Alterations of the skin in Acne inversa are very painful and involve limitation in movement. Inparticular, the location of inflamed fields in the intimate areas and the pus flow is often humiliatingfor the affected person. Thus, patients are frequently socially isolated, sexual impaired and can alsodevelop depression.Acne inversa patients do not only suffer from skin alterations. In many cases we also find metabolicalterations. In comparison with the total population there is frequently strong appearance of obesity,fat metabolism disorder type 2 diabetes mellitus or high blood pressure. These accompanyingdiseases are already repeatedly observed in very young patients. Accordingly, regular analyses of theblood pressure, glucose levels, and blood lipids as well as lifestyle improvement measures arerecommended (see below). Furthermore Acne inversa patients frequently suffer from chronicinflammation of the gut as well as joint and back pain.
Current therapy options of Acne inversa are still quite limited. However, various new medications (drugs) are in progress that are based on the current knowledge of the disease. Expectations ofbetter treatment strategies for these patients are high.
Nowadays practice involves certain Laser therapies that eliminate hair follicles, drug therapies andsurgical interventions. So far, there is only one approved medical therapy that is anti- inflammatory:TNF-alpha-drug Adalimumab. Another common used medication is the advanced antibiotic therapywhich is often a combination of Clindamycin and Rifampicin. Both treatments are showing limitedefficiency and are not able to reverse the structural alterations (fistula ducts, scarring) of the skin. Forpatients that are severely affected, that is, with strong involvement of fistula ducts and scarring(impaired movement), the therapy is to remove the involved skin over a large area. In addition `de-roofing` is also an option. Here the surgeon opens the fistula roof. A combination of surgicaltreatment and drug therapy seems reasonable in order to reduce inflammation and structural skinalterations. In general, therapy for Acne inversa also includes supporting nursing measures and lifestyle improvement strategies such as a healthy diet, exercises and attitude to non-smoking. Given thefact that inflammation during Acne inversa goes beyond the skin area of patients, we ideally want thetherapy to relieve also accompanying diseases
Sabat R, Jemec GBE, Matusiak Ł, Kimball AB, Prens E, Wolk K. Hidradenitis suppurativa. Nat Rev Dis Primers. 2020 Mar 12;6(1):18. doi: 10.1038/s41572-020-0149-1.
Wolk K, Warszawska K, Hoeflich C, Witte E, Schneider-Burrus S, Witte K, Kunz S, Buss A, Roewert HJ, Krause M, Lukowsky A, Volk HD, Sterry W, Sabat R. Deficiency of IL-22 contributes to a chronic inflammatory disease: pathogenetic mechanisms in acne inversa. J Immunol. 2011 Jan 15;186(2):1228-39. doi: 10.4049/jimmunol.0903907.
Sabat R, Tsaousi A, Rossbacher J, Kurzen H, Fadai T, Schwichtenberg U, Schneider-Burrus S, Kokolakis G, Wolk K. Acne inversa/hidradenitis suppurativa: ein update. Hautarzt. 2017 Dec;68(12):999-1006. doi: 10.1007/s00105-017-4082-5.
Sabat R, Chanwangpong A, Schneider-Burrus S, Metternich D, Kokolakis G, Kurek A, Philipp S, Uribe D, Wolk K, Sterry W. Increased prevalence of metabolic syndrome in patients with acne inversa. PLoS One. 2012;7(2):e31810. doi: 10.1371/journal.pone.0031810
Schneider-Burrus S, Arpa E, Kors C, Stavermann T, Sabat R, Kokolakis G. Medikamentöse Therapie der Acne inversa. Hautarzt. 2018 Jan;69(1):58-63. doi: 10.1007/s00105-017-4094-1.
Psoriasis is one of the most frequent skin diseases. Approximately 2-3% of the population ofdeveloped countries are affected. For example, in Europe approximately 15 Mio people suffer fromPsoriasis. In principle this disease occurs in all ages, even in childhood. The most commonly diseaseonset is at 20 years of age or between 40 and 50 years of age.
Psoriasis is an inflammatory, non-infectious skin disease. The most common form is characterized bythe appearance of clearly defined, thickened, and very scaly skin lesions (`Plaques`) (Psoriasisvulgaris). Those lesions usually arise at mechanically stressed body parts such as the elbows, theknees and also at the head. Further, very rare forms of Psoriasis with deviating appearance aredescribed below. Patients with Psoriasis are often heavily burdened by the obvious visible skinalterations.
Up to 50% of these patients also display affected finger and feed nails. Those nail alterations aredescribed by small notches (dimple or dot), yellow-brown discoloration (oil-stains) or by lifting of thenail bed (onycholysis).
Moreover up to 25% of Psoriasis patients suffer from inflammation of the joints (Psoriasis-Arthritis,see below). Persistent and permanent joint pain or swelling of the joints should be clarified with arheumatologist.
It is not completely understood why some people develop Psoriasis. One part of affected people(especially those with an early age of onset) show hereditary predispositions. In this case certainfactors are able to trigger this disease. Certain triggers are infections such as sore throat or the flu,certain drugs (e.g. drugs for blood pressure such as beta-blockers, Lithium or anti-malaria drugs),mechanical skin irritation (injury) or psychological stress factors.
There is clear evidence for the important role of the immune system in origin and persistence ofPsoriasis. Inflammation of the affected skin is induced by a variety of immune cells that infiltrate theskin. The main players among these immune cells in the skin of Psoriasis patients are the T cells.
The migration of immune cells from the blood into skin or other tissues of the body is a standardfunction of the immune system to protect the body from infections or cancer cells. In Psoriasis,however, there are no elements that need to be fought in the skin. It is an important research field toclarify if skin self-molecules are classified as dangerous by patients’ immune system.
Immune cells that have immigrated to the psoriatic skin produce inflammatory substances such asTNF-alpha, interleukine-17 or interlekin-22. Those inflammatory substances are called cytokines andare able to stimulate other cells to change their function or to produce other cytokines. Indeed,cytokines are capable of affecting and activate local skin tissue cells to produce substances thatattract immune cells. In addition, cytokines support the increased formation of new cells in the upperskin layers, which in the long term leads to thickening of the skin with severe scaling and thus to theskin changes typical of Psoriasis.
Psoriasis vulgaris is the most common form of Psoriasis and affects approximately 80-90% ofpatients. Psoriasis vulgaris is described by the already mentioned typical scaly, thickened skin lesions(plaques) that are mostly located at the bend sides of arms, legs and the head or in the area of thelower back. Plaques can vary in size: from small (0.5 - 2.0 cm) to bigger plaques with a diameter from10 - 20 cm or even more.
If the patient develops fast-spreading papules (nodes) and plaques (0.5-1.0) at the body, arms andlegs, it results in Psoriasis guttata (guttata = teardrop-shaped). This is often seen as the first sign ofillness in infants post infection (e.g. bacterial sore throat).
Other body parts can also be affected by Psoriasis such as e.g. in large body folds (groin, armpits,gluteal fold) or at the genital area. This type of psoriasis is called Psoriasis inversa (=reverse, appearsat atypical areas). The absence of the typical scaling is often replaced by badly reddened, raisedlesions that are in parts combined with very painful tears of the skin.
Furthermore, palms and soles can have reddened, scaling plaques and therefore lead to painful tearsin the skin (rhagades). This type of Psoriasis is called Psoriasis palmoplantaris (Palma=palm; Planta=sole).
In very rare cases (e.g. after heavy infections), skin irritations can spread and might lead to rednessover the whole body. This type is called erythroderma. Many patients affected by erythrodermasuffer from shivering and feeling sick. In general, hospital care is recommended.
Moreover, there are more specific types of Psoriasis that present a quite different clinical picture. Psoriasis pustulosa is described by the appearance of pus blisters (pustules) on top of the reddened,scaling skin. Dermatologists differentiate between generalized (large-scale) and locally restrictedtypes such as palms and/or soles of affected areas. In case of deterioration of skin diagnostic (boost),the annular (ring form) Psoriasis pustolosa can evolve from Psoriasis vulgaris. Small pus blistersappear around plaque borders. This accentuation of the border of plaques resemble rings. Psoriasispustulosa generalisata (Zumbusch type) is a heavy and rare progressive form of Psoriasis. Here,rapidly developing dark-red skin lesions all over the body are seen, on which millimeter-sized pusblister develop and in turn can merge into a large “pus sea”. At the edge we often find an inwardsdirected scaling ( ́dandruff ́). If those pustules detach, large plain open wounds (erosions) can beformed. Affected patients develop a distinct illness with fever and swelling of the lymph nodes. Dueto the huge inflammation of the skin, patients suffer from water and thermal deficit, requiringprompt hospital admission and initiation of therapy.
One of the locally restricted pustulosa types of Psoriasis is Psoriasis pustulosa palmoplantaris. Thistype only appears on the palms and soles. Typical for this type are the so-called sterile pus blisters(pus without infection) on the reddened skin of palm and soles. They can than turn into brownishmillimeter-sized scab crusts. This illness occurs more frequently in women and can be negativelyinfluenced by smoking. Therapies that we effectively use for Psoriasis vulgaris show only limitedeffect on these skin irritations. As a result of these distinctions, it is controversial to define thisdisease to a type of Psoriasis. So, here usually the term Pustulosis palmoplantaris is used. A similarcase applies to another localized pustulosa type of skin irritation called Acrodermatitis chronicasuppurativa Hallapeau (Akren=fingers, toes...). This condition is described by an infection of the skinin the area of nails and with redness and pus blisters which often occur initially on single fingers ornails. Infections can be accompanied by disturbed growth and even the loss of a whole nail
Almost a quarter of patients with Psoriasis suffer from bone-joint-disease (Psoriasis arthritis). Amajority of these patients develop these alterations many years after the onset of skin inflammation.However, approximately ten percent of those patients develop bone-joint-disease prior Psoriasis,which makes diagnosis more difficult. Frequently, the small joints at hands and ankles are affected.Sometimes all joints of a finger or a toes are affected and get swollen (aktylitis). Also larger jointsmight get involved and show inflammation and swelling such as the knees, hips or shoulders. Inaddition, an involvement of the axial skeleton (spine) is frequent. This typically appears with morningdeep-seated back pain that improves with movement.
A further characteristic of Psoriasis is an inflammation of the tendon insertions at the bones(enthesitis). They can express in e.g. pain and swelling of the Achilles (heel area).
Accompanying metabolic changes
Severe Psoriasis can involve metabolic changes. In fact, in comparison to total population there isevidence for numerous cases with high blood pressure, type 2 diabetes mellitus, obesity, anddyslipidemia. They can increase the risk of cardiovascular diseases. Thus those patients should betightly checked for blood pressure, blood sugar and blood lipids.
Therapy strategies depend on the severity of disease and involvement of nails or joints as well as theaccompanying diseases and patients’ preferences.
In less severe cases, an external treatment with, for example, vitamin-D-analogs and glucocorticoidsis sufficient.
Apart from various light and bath treatments, the skin in moderate or severe types of Psoriasis is notdirectly treated, but suppression of the immune system with injections or pills is indicated (systemictherapy). Fortunately, in the last past years many effective drugs have been developed whichimplement an individual therapy. The current spectrum of systemic therapies includes classicalimmune suppressive drugs (inhibition of the immune system with methotrexat and ciclosporin) aswell as low-molecular, chemical compounds (small molecules; e.g. Apremilast) along with highlycomplex, biological compounds ( ́biologics ́). The latter include antibodies that are directed againstthe cytokines TNF-alpha (e.g. Adalimumab and Infliximab), interleukine-17 (e.g. Secukinumab andBrodalumab) or IL-23 (e.g. Guselkuman and Risankizumab). Such biologics facilitate a focusedblockage of the key cytokines within the skin and often also within the inflamed joints and thereforean inhibition of defined immunological cascades.
Sabat R, Wolk K. Pathogenesis of Psoriasis. In: Sterry W, Sabat R, Philipp S, editors. Psoriasis: Diagnosis and Management, Part II: Etiology and pathogenesis: Wiley-Blackwell; 2014. p. 28-48
Sterry W. Plaque psoriasis. In: Sterry W, Sabat R, Philipp S, editors. Psoriasis, Diagnosis and Management, Part III: Clinical features/diagnostic procedure: Wiley-Blackwell; 2014. p. 57-75
Philipp S, Kokolakis G, Sabat R. Systemische Therapien der Psoriasis und Psoriasisarthritis. Hautarzt. 2016 Jun;67(6):464-71. doi: 10.1007/s00105-016-3812-4.
Nast A, Amelunxen L, Augustin M, Boehncke WH, Dressler C, Gaskins M, Härle P, Hoffstadt B, Klaus J, Koza J, Mrowietz U, Ockenfels HM, Philipp S, Reich K, Rosenbach T, Rzany B, Schlaeger M, Schmid-Ott G, Sebastian M, von Kiedrowski R, Weberschock T. S3-Leitlinie zur Therapie der Psoriasis vulgaris Update - Kurzfassung Teil 1 - Systemische Therapie. J Dtsch Dermatol Ges. 2018 May;16(5):645-670. doi: 10.1111/ddg.13516_g