November 21, 2011

Ambiguous Itching
By Jaimie Lazare
For The Record
Vol. 23 No. 21 P. 24

Because it is a common symptomatic complaint that can be difficult to diagnose, itching can complicate the diagnosis of pruritus.

We’ve all experienced the uncomfortable sensation of pruritus (itch) that causes us to scratch for relief. However, some itching sensations can result in continued scratching, causing inflammation, cuts, and secondary skin infections from the itch-scratch cycle that ensues.

At times, the itch-scratch cycle can mask the primary cause of the itch because it results in secondary skin lesions such as eczematous changes, lichenification, and excoriation.1 As the most common dermatologic symptom, itch can occur with or without any visible skin changes, can be generalized or localized, and its duration can be acute or chronic. Itch is a complex condition because the causes and presentations are heterogeneous, which can make diagnosing it extremely difficult in some cases.2

The International Forum for the Study of Itch proposed a new two-step classification for categorizing pruritic patients. The classification uses three groups to categorize patients with itch: Group I is itch on diseased skin; group II is itch on nondiseased skin; and group III is itch on secondary skin lesions. Additionally, it identifies six categories of pruritogenic diseases: dermatologic, systemic, neurologic, psychogenic, mixed, and other pruritus. As a result, patients categorized under diseased skin (group I) would be categorized under dermatologic pruritus.2

Although pruritus is a common condition, there are few studies examining itch. Studies include either very small populations or have significant selection bias. One retrospective study of 4,000 patients aged 65 and older reported that itch contributed to 11.5% of hospital admissions, making pruritus the third most common cause of older adult hospitalization in that study.2

“Itch is very common among older patients. It’s probably one of the most common complaints that we as dermatologists encounter in the older population,” says Mary Sheu, MD, an assistant professor and associate residency program director in the department of dermatology at Johns Hopkins School of Medicine. “With age, our skin produces less oil than it did when we were younger, and there’s a decrease in collagen production that makes the skin more susceptible to environmental assaults like a dry environment that causes cracking of the skin or topical irritants like soaps.”

Causes of Pruritus
Itch without an obvious cause is referred to as senile pruritus, explains Mary Gail Mercurio, MD, an associate professor of dermatology and of obstetrics and gynecology and the dermatology residency program director at the University of Rochester School of Medicine in New York.

The most common cause of itching among elder patients is xerosis (dry skin). One study showed that the prevalence of xerosis among community-dwelling older adults was as high as 38.9%. Other studies that looked at elder patients in long-term care facilities showed that the prevalence of xerosis ranged from 29.5% to 58.3%.3

While xerosis is a common cause of pruritus, skin itch can also be caused by age-associated skin changes, such as a decrease in lipids on the skin surface, a reduction in sweat and sebum production, and diminished barrier repair.4 Certain systemic diseases that cause itching are more common in older patients, such as chronic kidney disease, hepatic dysfunction, and endocrine disorders; infectious etiologies of pruritus, (eg, scabies, lice) are commonly seen among patients living in institutional settings.4 Another cause of itch among patients living in such environments is artificial air, which can trigger several problems, including dry skin, says Robert Norman, DO, a geriatric dermatologist in Tampa, Fla.

While medications can cause allergic reactions that can manifest themselves in the skin and cause itching, there are some medications that don’t necessarily cause an allergic type of rash but on their own can cause itching, Sheu says. Common ones include opioids, anticholinergic inhibitors, and aspirin. These medications can cause some histamine release and other mechanisms that can trigger itching without a rash, she says.

Sheu explains that although malignancy shouldn’t immediately come to mind when diagnosing itch in an older patient, some itch may be indicative of an underlying cancer such as a lymphoma, a solid tumor, or other internal malignancies such as myelodysplastic syndromes. In general, malignancies are more common in the older population, so in an older individual experiencing chronic itching without a visible rash, a workup for a potential malignancy is warranted, she says.

With increasing age, there’s an accompanying decline of normal immune function that results in a higher frequency of autoimmune skin disorders (eg, bullous pemphigoid) that may lead to pruritic symptoms.4 “Bullous pemphigoid is a blistering skin disease in elder patients that commonly starts out as very itchy hivelike lesions, and a skin biopsy can confirm the diagnosis,” Mercurio says.

Evaluating Itch
With all the possible causes of itch, a diagnosis may not be obvious. When a patient presents with a complaint of itch, providers will want to determine whether he or she has an accompanying rash with the itch and whether the itch is localized or generalized. This information will provide relevant clinical clues about the cause of pruritus.1 The location of the itch should be considered since there are certain areas of the body where itch is more common, such as around the shoulder blades, on the back, on the calf, and on the topside of the forearm, Sheu says. These are areas in which, for unknown reasons, it’s common to develop localized patches of itching that then cause scratching, further disrupting the skin barrier and allowing the entry of outside substances that create further irritation, making patients itch more and exacerbating the itch-scratch cycle, she explains.

Norman suggests physicians check the lower extremities for dry skin that has a cracked porcelain appearance (called eczema craquele) that’s easy to spot but can lead to more skin breakdown and eczema. Another recommendation is for physicians to look at the medial aspect of patients’ ankles for signs of ulcer formation because that’s the most common area for skin breakdown and ulcers, which can come from an initial area skin excoriation, he says.

“Environmental factors rarely contribute to itch without a rash. Environmental factors can definitely be a cause of dermatitis, such as poison ivy. A primary rash that is causing the itching, such as scabies, on close examination of the skin would reveal burrows and a characteristic distribution,” Mercurio says.

When patients complain of itch, physicians should ask whether they’ve had a skin rash, whether it’s just itching, what medical problems they have, and what medications they are taking, says Mercurio.

Sheu says questions about seasonal predilections and what time of the year itching occurs can help identify the cause. Physicians should ask patients whether the itch occurs in the winter with dry, cold weather; in the summer because warm skin is more likely to become itchy; or whether it occurs year-round.

With generalized itching, it’s more likely to be an allergic reaction or a condition such as gallbladder or liver disease because these conditions cause disseminated itching, Norman says.

When over-the-counter medications or complementary and alternative medicines are involved, physicians need to consider itching from another perspective, evaluating what nonprescription medications patients are using vs. what they’re being treated with, Norman says. “Patients do not always include these nonprescriptive drugs when discussing their medications with physicians, and some of these drugs may make patients pruritic,” he says.

Mercurio says physicians should make sure there isn’t a skin disease causing the itching, such as urticaria (hives), bullous pemphigoid, dermatitis, scabies, or ringworm. Physicians should examine the skin closely for specific features of these skin diseases. A biopsy or a skin scraping in the case of scabies or ringworm may be warranted, she says.

If an infectious cause for itch is suspected, Sheu recommends physicians check for lice in the scalp, examining for evidence of scabies between the fingers, and looking for the burrows of scabies. Physicians should also look in areas where older patients may be unable to reach, such as the back, because if there’s a visible skin lesion, a primary skin problem rather than something induced by scratching should be considered a possibility, she says.

Itch in older patients could also be atopic dermatitis. Norman notes that 10% of children with atopic dermatitis have it throughout their lives. Atopic dermatitis is sort of an underdiagnosed cause of dry skin and itchy skin, and should be considered in the differential diagnosis, he says.

Ditch the Itch
The first-line treatment for itch is an antihistamine—ideally one that is nonsedating during the day and sedating at night, Mercurio says. Other less common treatments include phototherapy and the medication gabapentin. Pruritus can be debilitating, and a stepwise treatment approach to improve a patient’s condition is essential, she says.

“Phototherapy occurs in a medically controlled setting, usually in a dermatologist’s office. It’s basically getting into a medical-grade tanning booth with specific wavelengths of light that seem to be able to help some individuals with chronic pruritus,” Sheu says.

She suggests older patients switch to a moisturizing soap and a barrier type of moisturizer because in her practice such steps alone reduce about one-half of the dermatology consults for itch. There are potential treatment options, such as over-the-counter and prescription topical therapies, but the nonsteroidal options (eg, tacrolimus) are actually better for older patients because steroids can thin the skin. Some over-the-counter options, such as topical menthol preparations, can cool the skin and make it feel better, Sheu says.

Certain studies have shown that factors affecting the efficacy of emollient application among older adults include a lack of routine adherence and applying inadequate amounts. There is also evidence that routinely applying emollients by gently rubbing them into the skin within three minutes of bathing helps trap moisture in the skin.3

Topical products such as CeraVe and Cetaphil are often used to treat skin itch. CeraVe is made up of ceramide, which helps repair the skin barrier. Previous moisturizers acted more like symptom relievers for dry skin and itch. New products such as CeraVe relieve symptoms as well as help treat the underlying problem so the symptoms dissipate, an interesting shift in the way these moisturizers work, Norman says.

Castiva, with capsaicin as an active ingredient, provides a heating effect that works for older patients with itchy scalp. The cooling form of Castiva uses castor oil and menthol. Both types can be used for joint pain in older adults, he says.

Managing the Intractable Cases
“Any of the causes of itching can be extreme depending on the patient. Basically, the itching of an underlying skin disease such as bullous pemphigoid or scabies can be extreme as can the itch with no apparent cause,” says Mercurio, who recalls seeing a patient who experienced terrible itching for six months and was unable to sleep through the night or function during the day. The patient had been prescribed numerous medications and experienced many side effects, including dizziness that caused her to fall and fracture her wrist. A scraping of the skin revealed a scabies mite, and the itching disappeared following one week of treatment, she says.

Sheu says if itch is prolonged and extreme, practitioners should consider an underlying medical condition, such as an internal problem (eg, liver disease, kidney disease, lymphoma), and recommend additional tests other than the usual blood tests, such as different radiology scans. Sheu recalls a patient with severe itching who had been undiagnosed for a long time. After further tests, it was revealed that the patient had mycosis fungoides, a skin lymphoma, which has an eczematous rash in the trunk area.

For treating itch without a specific cause, fexofenadine, a second-generation nonsedating antihistamine, should be considered because it doesn’t cross the blood-brain barrier, dosing requires doubling the package insert’s recommendation (ie, 180 mg twice daily), and it’s a less expensive generic medication. Another approach to treating idiopathic total body itch would be to prescribe prednisone using a low-dose alternate-day dosing method to decrease the risk of just about all adverse events associated with this medication.5

In older individuals, antihistamines, specifically the sedating ones, must be used cautiously, especially in terms of dosing, Sheu says. In terms of how to help your patient cope psychologically, use whatever supported measures can be taken to help relieve the itch. Reassure patients, especially if the cause is not yet known, by letting them know that tests are being ordered and the work is being done to determine what is causing the itch, she says.

— Jaimie Lazare is a freelance writer based in Brooklyn, N.Y.

References
1. Ward JR, Bernhard JD. Willan’s itch and other causes of pruritus in the elderly. Int J Dermatol. 2005;44(4):267-273.

2. Reich A, Stander S, Szepietowski JC. Pruritus in the elderly. Clin Dermatol. 2011;29(1):15-23.

3. White-Chu EF, Reddy M. Dry skin in the elderly: Complexities of a common problem. Clin Dermatol. 2011;29(1):37-42.

4. Patel T, Yosipovitch G. The management of chronic pruritus in the elderly. Skin Therapy Lett. 2010;15(8):5-9.

5. Nash K. Total body itch with no clear cause puzzles patients, physician. Dermatology Times. November 1, 2010. Available at: http://www.modernmedicine.com/modernmedicine/Modern+Medicine+Now/Total-body-itch-with-no-clear-cause-puzzles-patien/ArticleStandard/Article/detail/692397?contextCategoryId=40160. Accessed May 12, 2011.