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Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Psoriasis is a chronic, noncontagious, multifactorial inflammatory skin condition that has several subtypes. The five major forms are plaque, inverse, guttate, erythrodermic, and pustular psoriasis.[1-6] The classic lesion is a pink plaque topped with a micaceous (micalike) scale (shown).[1] Forcible removal of these scales may cause pinpoint bleeding (Auspitz sign).[2] Some scholars believe many biblical descriptions of leprosy were actually those of psoriasis. Although the immune system is involved, particularly T cells, and some patients have a genetic predisposition, many unknowns remain about what factors trigger its onset, cause a flare, and determine the extent and particular pattern.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Psoriasis can affect any age group but primarily occurs in those 15-35 years of age and those 50-60 years of age.[1,3,6] Therapy is based on the psoriasis subtype, site and size of the area(s) involved, and severity of the eruption.[1] Note that although systemic steroids may lead to rapid clearing of psoriasis, these agents should not be used in the event that if they are abruptly discontinued, a limited plaque psoriasis may blossom into potentially life-threatening generalized pustular or erythrodermic psoriasis.

Psoriasis may also be associated with other conditions (eg, arthritis, cardiovascular [CV] disease, diabetes, depression).[3] The presence of psoriatic arthritis (shown), which may occur in up to 30% of patients with psoriasis,[2,4] usually mandates some form of systemic therapy, even if the skin involvement is relatively limited. Although psoriasis has no potential to evolve into skin cancer, some of its treatment options may increase the risk for certain cancers.[1,3]

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Plaque Psoriasis

Plaque psoriasis (psoriasis vulgaris) is the most common subtype of psoriasis.[2,5] Although it may occur on any location on the body, some areas are classically affected (eg, knees, elbows, lower back) (shown).[1,5,6] The plaques may be pruritic or feel sore, or they may be asymptomatic. Some patients will seek help when only a few small scaly papules appear on the knees and elbows; others, however, may ignore the lesions for a very long time, especially if "everyone in the family has this." The face is rarely involved; it is unclear whether the lack of facial involvement is due to chronic ultraviolet (UV) light exposure or some other factor that is unique to facial skin. Sun-exposed areas of the arms may also be relatively spared. Phototherapy is an effective therapeutic option for psoriasis.[1,5,6] As the condition is treated and improves, the scales may mostly regress and leave the pink plaques behind, which eventually flatten to a pink patch. The skin color at the site of a treated plaque may not return to normal for a very long time or be permanent in some cases.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Psoriasis usually consists of pink to red lesions on the skin of white patients. However, as is the case with many other inflammatory conditions, the lesions may have a dusky violaceous (purple) appearance on individuals with darker skin, especially in those with an African background. Treatment for psoriasis may be the same for any skin type; however, strong topical corticosteroids have a pigment-bleaching effect that may cause the skin defect to be more noticeable on dark-skinned persons, even if the psoriasis itself is responding to therapy.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Inverse Psoriasis

Inverse psoriasis affects areas with skin folds (retroauricular [center], axillary [right], inframammary, abdominal, inguinal, and genital sites), usually has much less scaling than in a typical plaque type psoriasis, and will usually respond to topical or systemic therapy.[1,5,6] It is often mistaken for fungal infection or a skin allergy. Clinicians should take care to avoid causing skin irritation from the use of some topical treatments and also prevent skin thinning and striae formation that may develop from long-term use of strong corticosteroids in skin folds.[1,6] Genital psoriasis (left) appears pink or red, with relatively thin plaques and little/no scale; if psoriasis is present in other body areas, empiric therapy before biopsy is usually acceptable. Potent topical corticosteroids may be needed to clear the lesions. Consider biopsy for atypical lesions or persistent plaques to exclude squamous cell carcinoma or extramammary Paget disease. The gluteal cleft is often involved in psoriasis subtypes; the presence of "gluteal pinkening" may help clinicians to make the diagnosis of psoriasis in patients with equivocal findings elsewhere on the skin.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Guttate (Eruptive) Psoriasis

Guttate ("droplike" or eruptive) psoriasis, the second most common subtype of psoriasis, occurs in about 10% of those with psoriasis.[3] It is often seen in younger patients (children, young adults)[3] and may present as a relatively sudden worsening of a preexisting plaque psoriasis or the first and only presentation of psoriasis.[3,6] Coexisting infections (Streptococcus pyogenes infection; "strep throat" or "perianal strep") may trigger the disease.[1,3,6] Some clinicians may initiate empiric therapy for group A streptococcal infection when they start to treat the skin eruption, which is characterized by dozens or hundreds of small pink papules topped with a fleck of psoriatic scale (shown). These lesions tend to itch more than other forms of psoriasis, which may cause them to be confused with other types of rashes (eg, drug eruptions, pityriasis rosea). Guttate psoriasis presents a therapeutic dilemma, as the area of involvement is usually much more extensive than can managed with topical therapy alone. However, this disease responds especially well to UV phototherapy and, when that is not practical or available, natural sunlight is also effective.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Erythrodermic Psoriasis

Erythrodermic ("red skin" or exfoliative) psoriasis, a rare (about 3% of psoriasis patients) and potentially life-threatening condition, is characterized by widespread erythema and scaling of the skin.[1,3,6] It may result from refractory or untreated psoriasis, or it may be induced by severe sunburns or medications as well as withdrawal from oral corticosteroids.[1,3] Patients are often febrile, have an elevated white blood cell (WBC) count, and suffer a generalized malaise. Due to increased shunting of blood to the skin, patients may become hypothermic and hypotensive; older patients with more fragile CV systems may go into high-output cardiac failure. In more chronic cases of erythrodermic psoriasis, an increased skin metabolism and turnover rate can cause nutritional difficulties.[3] Affected patients often require hospitalization, especially if they are older or have comorbid conditions. The differential diagnosis includes severe drug eruptions, cutaneous T-cell lymphoma, pityriasis rubra pilaris, and severe seborrheic dermatitis (which may be associated with progressive human immunodeficiency virus infection). Treatment is supportive and may include topical or systemic agents.[3]

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Pustular Psoriasis

Pustular psoriasis is a noninfectious, noncontagious, potentially life-threatening condition that has two primary variations: Von Zumbusch is the generalized form (right), whereas acrodermatitis continua of Hallopeau affects the hands and feet (left). The generalized type is mainly seen in adults; it is characterized by lakes of sterile pus and reddened skin that often itch and burn.[3] The disease may present alone, or there may be other sites with plaque psoriasis. Patients may have disabling malaise, elevated WBC count, and fever,[6,7] which may be misinterpreted as evidence of infection. Triggers may include drugs, the abrupt withdrawal of systemic corticosteroids, and infectious or chemical exposure.[1,3] Generalized pustular psoriasis usually requires hospitalization for supportive care and systemic therapy, as the affected sites are usually too large to manage with topical medications alone.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Acrodermatitis Continua

Unlike patients with Von Zumbusch pustular psoriasis, patients with pustular psoriasis of the palms and soles are less likely to have generalized signs/symptoms, although they may have severe pruritus. Triggers include local trauma or infection.[3,7] Even with relatively limited involvement of the total body surface area, involvement of the feet may make walking impossible and involvement of the hands, including potential superficial infections of deep fissures that may occur in severe disease (shown), may make patients unemployable. Bacterial culture and result-directed antibiotics may sometimes be necessary to enable more effective therapy with standard psoriasis treatments. Avoidance of open wounds and fissures is especially important in patients who are on long-term immunosuppressive medications. Topical therapies may be tried, but there may be limited penetration through thicker acral skin and through the lakes of pus. Thus, severe acral psoriasis may best treated with systemic therapy.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Recovering Pustular Psoriasis

This image shows a treated case of palmar pustular psoriasis in which most of the inflammation has subsided with the use systemic immunosuppressive therapy. The flaking and peeling of skin where the lakes of pus once were will persist for weeks, but they can benefit from aggressive moisturization. Regardless of the cause of the condition, flaking of the skin is expected as the inflammation and swelling recede.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Scalp Psoriasis

At least 50% of patients with psoriasis have scalp involvement,[3] and it may be their only psoriatic manifestation. The entire scalp may be involved, or the disease may be localized (eg, occiput; periauricular or anterior hairline, sometimes extending onto the forehead [left]).[3] Psoriasis and seborrhea features may overlap; many clinicians use the term "sebopsoriasis" to describe the widespread red plaques and thick scaling on the scalp, and patients may have self-diagnosed their condition as particularly bad dandruff (seborrheic dermatitis). Many of the same treatments (eg, topical corticosteroids, tar shampoos) will help both conditions. However, scalp psoriasis may be harder to treat than plaque psoriasis owing to difficulty in the ability of the agents to penetrate down to the skin. A pretreatment trial of salicylic acid shampoo or peanut oil or other keratolytics may help to remove/loosen scales and allow topical agents to reach the inflamed skin. Systemic therapies may be needed for adequate control of the disease, especially in patients who cannot or will not wear their hair shorter. The image on the right shows partially treated scalp psoriasis.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Shaving the head to allow better application of medications may cause problems in and of itself. In what may be thought of as Koebnerization of the scalp (whereby a rash is caused by trauma/injury), patients with active or latent psoriasis may find that a close haircut or other hair treatments is followed by a natural spiking of the hair known as "the tee-pee sign" (shown). This sign has also been seen in individuals with severe seborrhea, but even subtle scalp inflammation in psoriasis can induce this growth pattern after relatively minor scalp trauma.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Psoriatic Nails

Psoriasis may affect fingernails and toenails; this may be the only expression of psoriasis in some patients. Psoriatic nails may be indistinguishable from onychomycosis and, due to the presence of subungual debris, they may be more susceptible to fungal infection than normal nails. A combination of "oil spots" (yellow to brown discolorations under the nail plate) (left), small pits on the nail surface, distal onycholysis (center), and subungual debris may be present. Systemic medications are often more effective than topical agents. Alternatively, corticosteroid injection (eg, triamcinolone) directly into the nail matrix (right) may be reasonable if only a limited number of nails are affected. Although the injections can be painful, they may improve inflammation and, ultimately, nail appearance. Existing nail deformity cannot be undone quickly. Complete replacement of a fingernail may take 6-9 months; it is about 1.5 years for a big toenail. Some studies suggest that patients with refractory hand psoriasis and severe nail involvement may be more likely to develop psoriatic arthritis, especially in the distal interphalangeal joints.[8]

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Psoriatic Arthritis

Psoriatic arthritis tends to preferentially affect smaller joints rather than the axial skeleton. This condition can be progressive and crippling, and it may coexist with other types of arthritis. With the exception of acitretin, any systemic medications prescribed for psoriasis of the skin should help in the management of coexistent psoriatic arthritis and vice versa. A potential treatment complication may occur if the arthritis is managed with nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen or naproxen; these agents may cause skin psoriasis flares in some patients.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Koebner Phenomenon

The Koebner phenomenon is seen in a variety of inflammatory skin conditions, including psoriasis. It is characterized by relatively minor trauma inducing the onset of an underlying skin condition in the area of injury. In cases of psoriasis that demonstrate this phenomenon, lesions may be found in scratch lines (right), abrasion patches, minor burns, and postsurgical scars. Caution patients with active psoriatic disease to avoid unnecessary decorative skin trauma such as tattoos and body piercings. Although UV light is generally beneficial for most forms of psoriasis, another expression of the Koebner phenomenon may be sunburns, which can cause a severe flare (left; center).

Sources of image data: National Psoriasis Foundation[9] and American Academy of Dermatology.[6]

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

No cure for psoriasis currently exists; however, different treatment modalities may be used to ameliorate signs/symptoms of the disease, heal skin lesions, prevent comorbidities, ease the disease burden, reduce the risk of toxicities, and improve quality of life. Every patient is unique not only in the severity and distribution of their psoriasis but also in their response to therapy; therefore, all treatment should be personalized.[3,6] Nonetheless, direct-to-consumer (DTC) advertising heavily targets patients to "ask your doctor" about some of the newer and more innovative treatments for psoriasis, and fellow psoriatic patients also make recommendations via chat rooms and other patient support resources.

Images courtesy of Getty Images (ointment) and Wikipedia (prednisolone molecule).

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Topical Treatment

Topical corticosteroids remain the mainstay of therapy for most patients with mild, limited, or early psoriasis[1,3,9,10]; these agents are also used to manage flares and resistant areas in those on systemic therapy. Avoid long-term, unsupervised use of potent steroids in the skin folds. Consider early systemic therapy for severe disease, especially if joints are affected, because thick plaques often require stronger therapy. Monotherapy with vitamin A or D analogues is often incompletely effective, but these agents may be used with potent topical steroids to reduce the overall frequency of applications and to take advantage of the synergy between dissimilar drugs. Salicylic acid shampoos are useful to remove psoriatic scales on the scalp, and they can be used as a body wash. Foams, creams, and lotions that gently loosen body scales include urea, lactic acid, and ammonium lactate. Various tar preparations are effective for mild psoriatic disease, but they have a strong odor, are messy to use, and may stain the skin or clothing.[1,3] There is also some concern over long-term effects (eg, skin cancer).

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Therapeutic phototherapy generally utilizes broadband or narrow band UV B (UVB) or UV A (UVA) light, following psoralen sensitization (psoralen plus UVA [PUVA]).[1,3,6] This is a useful treatment modality for patients with widespread psoriasis (ie, moderate to severe disease) who also have medical comorbidities, but it is not effective for psoriatic arthritis. Commercial tanning booths predominantly emit UVA rays which, without psoralen sensitization, is of much less use in treating psoriasis. Most tanning units also produce some UVB rays; although some treatment benefits may be seen, commercial units seldom clear psoriasis as rapidly or as effectively as prescription phototherapy units. However, relative to medical phototherapy, commercial tanning salons are always more available to, and sometimes much less expensive for, patients. Note that UV light from any source increases the long-term risk of melanoma.[1,3,6]

Photodynamic therapy (administration of a light source after applying a sensitizing chemical) has been reported to be of benefit in some studies but not in others.[11] Lasers such as the excimer laser can provide narrow band UVB to very specific areas without having to irradiate the whole body.

Molecular structures courtesy of Wikimedia Commons.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Systemic Therapy

Consider systemic therapy for patients with widespread lesions, involvement of difficult-to-treat (eg, scalp, nails) and/or critical areas (eg, hands, feet), and coexistent arthritis, and for psoriasis refractory to a reasonable trial of topical therapy (moderate, severe, disabling disease). Systemic therapy includes the use of disease-modifying antirheumatic drugs (DMARDs) (eg, cyclosporine, methotrexate [MTX], acitretin) and biologic agents, as well as other medications such as apremilast.[1,3,6] Research into anecdotal reports of other effective treatments as well as drugs not yet approved for psoriasis by the Food and Drug Administration is ongoing.

Cyclosporine, originally approved as an antirejection agent for organ-transplant recipients, quickly improves psoriasis. It is considered a temporary "rescue" agent while other drugs are started, but signs/symptoms may recur with rapid withdrawal. It does not cause hepatotoxicity, but nephrotoxicity may occur with long-term use, especially at higher doses.

Apremilast is an oral phosphodiesterase inhibitor that does not produce the global immune suppression seen with many other systemic psoriasis medications. It may not be quite as effective as the other medications when used by itself. Headache, diarrhea, nasopharyngitis, and nausea are the most frequent side effects.[12]

Image courtesy of Medscape.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

MTX, initially used to treat psoriatic arthritis, is a relatively affordable systemic agent that is effective for managing psoriasis. However, it may cause hepatotoxicity, along with less common potential adverse effects (eg, worsening of preexisting renal failure, especially in older patients; marrow suppression; pulmonary fibrosis). Monitor patients with routine bloodwork and liver function studies; with long-term MTX use, liver biopsy is recommended at some point.

Acitretin, an oral retinoid, does not suppress the immune system; in fact, it may have antineoplastic properties. It seems to be especially useful in hand/foot psoriasis but not for psoriatic arthritis. Although it has been available for about 20 years, acitretin is still rather expensive; it may also dry out the skin and mucous membranes and may worsen lipid and transaminase profiles. More significantly, pregnancy is contraindicated for 3 years after acitretin discontinuation because of the risk of teratogenicity caused by storage of the retinoid in, and slow leakage from, the fat cells.

Table adapted from Sivamani RK, Correa G, Ono Y, et al. Biological therapy of psoriasis. Indian J Dermatol. 2010 Apr-Jun;55(2):161-70.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Biologic Agents

An expanding family of biologic medications ("biologics") target very specific components of the immune system and inflammatory pathway.[1,6,13] Many biologic agents were previously approved for use in arthritis (psoriatic and rheumatoid) and inflammatory bowel disease (especially ulcerative colitis) before they were used widely and approved for the treatment of psoriasis. Advantages to using biologic agents include less global immune suppression and the infrequent dosing regimen for the injectable agents. Disadvantages include a proclivity to cause disease flares in latent tuberculosis and hepatitis B and the potential to increase the risk for malignant conditions.[1,3,6,13] In addition, these agents are expensive and US insurance companies will require evidence of other treatments having been tried and that those therapies either failed or caused significant side effects before approving the use of biologic agents to treat psoriasis.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Diagnostic Dilemmas

Psoriasis may be missed or misdiagnosed. Therapy can change the appearance of lesions and, sometimes, cause confusing histologic findings on biopsies. Many inflammatory, infectious, and neoplastic skin conditions may present as "red, scaly rings"; most will improve or temporarily seem to improve with topical steroid use. By the time patients see clinicians, most have tried to self-treat with over-the-counter (OTC) antifungal agents and leftover creams previously prescribed to them for other reasons or borrowed from others. Some will have tried various domestic/overseas Internet products, which may contain significant amounts of potent steroids. The image is from a typical patient who unsuccessfully self-treated her "ringworm" with an OTC antifungal. A prescription combination antifungal/corticosteroid seemed very effective. Although the morphology of the red rings is suggestive of tinea corporis, the lack of response to the initial self-therapy and the better response to the prescribed agent suggest that the corticosteroid was the effective component. The diagnosis of psoriasis is most likely with similar findings on the elbows and early psoriatic nail changes.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Chronic contact dermatitis (top left) and chronic hand eczema (bottom left) may resemble psoriasis. In fact, biopsies of these skin lesions may sometimes be interpreted as "psoriasiform dermatitis" (ie, even microscopically, the lesions look like psoriasis). Many psoriasis treatments (eg, topical corticosteroids, systemic immunosuppressive agents) may effectively treat chronic contact dermatitis and chronic hand eczema. However, other psoriasis treatment options (eg, topical retinoids, vitamin D analogues) may irritate the skin and exacerbate both conditions.

Not all red and scaly lesions are psoriasis. Crusted scabies (right) may resemble psoriasis of the hands, scalp, and body; in severe cases, it may even mimic erythrodermic psoriasis. Topical corticosteroids may temporarily improve signs/symptoms of crusted scabies, but the infestation will eventually worsen because of the immunosuppressive effects of these agents. Patients on systemic immune-suppression therapy for their psoriasis can also be prone to develop crusted scabies.

Image courtesy of Jeffrey Meffert, MD.

Psoriasis: Manifestations, Management Options, and Mimics

Jeffrey Meffert, MD | December 30, 2019 | Contributor Information

Many cutaneous malignancies have an inflammatory component which may demonstrate relative improvement with topical corticosteroid therapy. Some of these tumors are very slow growing and may be characterized by red plaques and scales similar to those seen in psoriasis (shown). Although it is possible to have a single psoriatic plaque, this is not typically the case, whereas cutaneous malignancies may present with a lone lesion. Other clues to differentiate between cutaneous malignancies and psoriasis include the presence of gluteal pinkening, nail pits, or a refractory dandruff, which support the diagnosis of psoriasis. A couple of useful dermatologic maxims may also apply, as follows:

  • If it is not responding to what should be effective treatment, biopsy it.
  • If the biopsy results don't make sense on the basis of the patient's history and physical findings, biopsy again.
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Decorative tattoos have become increasingly popular around the world--accompanied by a rise in related complications. Can you identify the following tattoo skin reactions?Slideshows, October 2019
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Psoriasis is a complex, chronic, multifactorial, inflammatory disease that involves hyperproliferation of the keratinocytes in the epidermis, with an increase in the epidermal cell turnover rate. Environmental, genetic, and immunologic factors appear to play a role.Diseases/Conditions, October 2019
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