View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by DigitalCommons@University of Nebraska University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln U.S. Air Force Research U.S. Department of Defense 2011 A Diagnostic Approach to Pruritus Brian V. Reamy Christopher W. Bunt Stacy Fletcher Follow this and additional works at: https://digitalcommons.unl.edu/usafresearch This Article is brought to you for free and open access by the U.S. Department of Defense at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in U.S. Air Force Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. A Diagnostic Approach to Pruritus BRIAN V. REAMY, MD, Uniformed Services University of the Health Sciences, Bethesda, Maryland CHRISTOPHER W. BUNT, MAJ, USAF, MC, and STACY FLETCHER, CAPT, USAF, MC Ehrling Bergquist Family Medicine Residency Program, Offutt Air Force Base, Nebraska, and the University of Nebraska Medical Center, Omaha, Nebraska Pruritus can be a symptom of a distinct dermatologic condition or of an occult underlying systemic disease. Of the patients referred to a dermatologist for generalized pruritus with no apparent primary cutaneous cause, 14 to 24 percent have a systemic etiology. In the absence of a primary skin lesion, the review of systems should include evaluation for thyroid disorders, lymphoma, kidney and liver diseases, and diabetes mellitus. Findings suggestive of less seri- ous etiologies include younger age, localized symptoms, acute onset, involvement limited to exposed areas, and a clear association with a sick contact or recent travel. Chronic or general- ized pruritus, older age, and abnormal physical findings should increase concern for underly- ing systemic conditions. Initial evaluation for systemic disease includes complete blood count and measurement of thyroid-stimulating hormone, fasting glucose, alkaline phosphatase, bili- rubin, creatinine, and blood urea nitrogen. Hodgkin lymphoma is the malignant disease most strongly associated with pruritus, which affects up to 30 percent of patients with the disease. Chest radiography is needed when lymphoma is suspected. A wheal and flare response indi- cates histamine-induced pruritus in patients with urticaria or an allergic dermatitis. These patients benefit from continuous dosing of a long-acting antihistamine. Second-generation antihistamines, such as cetirizine, loratadine, and fexofenadine, may be more effective because of improved patient compliance. (Am Fam Physician. 2011;84(2):195-202. Copyright © 2011 American Academy of Family Physicians.) ▲ Patient information: ruritus is the subjective sensation substances that can cause skin lesions. New A handout on pruritus, of itching. It can become severe cosmetics and creams can trigger allergic written by the authors of this article, is provided on enough to interfere with work and contact dermatitis, urticaria, and photo- page 203. restful sleep. Histamine is the pri- dermatitis. New drugs (medications, nutri- P mary mediator of itching in many disorders.1 tional supplements, illicit drugs) can lead to Antihistamines are effective in treating urticaria or fixed drug eruptions. Travel can histamine-mediated pruritus, but they expose a person to new foods that can trig- may be less effective in patients with dis- ger urticaria and to sunlight that can trigger eases that trigger pruritus through mecha- photodermatitis. Travelers are also suscep- nisms involving serotonin, leukotrienes, or tible to infestations, such as with scabies or neuropeptides.1,2 lice. Hobbies may expose the skin to solvents and topical agents that can trigger contact Evaluation dermatitis. Chronic occupational exposure The initial clinical approach in patients to solvents can dry the skin, causing xerosis with pruritus includes a history and physi- and atopic dermatitis or eczema. New ani- cal examination to determine if the pruritus mal exposures can lead to flea infestations, is caused by a dermatologic condition or is allergic cutaneous reactions to dander, and secondary to an underlying systemic dis- urticaria. Another important finding in ease. Figure 1 is a diagnostic algorithm for the evaluation of patients with pruritus is a pruritus. recent exposure to sick contacts who have The presence of a primary skin lesion may febrile diseases, such as rubeola, mumps, or aim the evaluation toward a dermatologic varicella, or exposure to infectious organisms cause. The history should focus on recent that can cause rashes, such as parvovirus, exposures to new topical, oral, or airborne Staphylococcus aureus, or Streptococcus July 15, 2011 ◆ Volume 84, Number 2 www.aafp.org/afp American Family Physician 195 Pruritus species. In the absence of a primary skin Physical examination should include an lesion, the review of systems should include evaluation of the liver, spleen, and lymph evaluation for thyroid disorders, lymphoma, nodes. Organomegaly increases the likeli- kidney and liver diseases, and diabetes mel- hood of an underlying systemic disease, such litus. Table 1 includes historical findings that as lymphoma. The skin should also be exam- suggest etiologies for pruritus. ined. Finger webs, intertriginous regions, and the genitals should be evaluated for the presence of scabies or lice. Diagnosing the Cause of Pruritus Historical and physical findings that sug- gest a less serious etiology include younger Patient presents with pruritus age, localized symptoms, acute onset, involvement limited to exposed areas, and a Perform history with review of systems, clear association with a sick contact or recent and focused physical examination travel.3-5 Chronic or generalized pruritus, age older than 65 years, and abnormal physi- cal findings should increase concern for an Primary skin lesion is identifiable? underlying systemic condition.3-8 If the diagnosis is unclear after the his- Yes No tory and physical examination or if initial History and empiric treatment is ineffective, a limited examination suggest laboratory evaluation should be performed, underlying diagnosis? including complete blood count and mea- surement of thyroid-stimulating hormone, fasting glucose, alkaline phosphatase, bili- Yes No rubin, creatinine, and blood urea nitrogen.5 Treat Perform initial testing: Consider the following tests if If immune suppression or lymphoma is Complete blood count systemic condition is suspected (e.g., age older than 65 years, generalized possible, a human immunodeficiency virus Measurement of fasting pruritus, chronic pruritus [three antibody assay and chest radiography should glucose, creatinine, weeks], abnormal physical findings): 5-8 blood urea nitrogen, also be performed. Further diagnostic thyroid-stimulating Human immunodeficiency virus tests may include biopsy, scraping, or culture antibody assay hormone, bilirubin, and of the skin or lesions. alkaline phosphatase Chest radiography Differential Diagnosis of Pruritus Diagnosis established? Pruritus can be a symptom of a distinct der- matologic condition (Table 2 7) or of an occult underlying systemic disease (Table 3 2,3,5,7,9,10). Yes No Treat Consider additional diagnostic COMMON DERMATOLOGIC CAUSES testing (skin or lesion): Atopic Dermatitis. Atopic dermatitis is char- Biopsy acterized by pruritus. It is generally defined Scraping (potassium hydroxide [KOH], mineral oil) as a chronic, relapsing inflammatory skin Culture (bacterial, viral, fungal) disease that often occurs in patients with a personal or family history of asthma or allergic rhinitis.11 In contrast to other der- Diagnosis established? matologic disorders, atopic dermatitis often lacks a primary skin lesion. Usually only the Yes No secondary cutaneous findings of excoria- tion, weeping, lichenification, and pigment Treat Referral changes are apparent.2 Contact Dermatitis. Contact dermatitis Figure 1. Diagnostic algorithm for pruritus. is a rash caused by direct skin exposure to 196 American Family Physician www.aafp.org/afp Volume 84, Number 2 ◆ July 15, 2011 Pruritus SORT: KEY RECOMMENDATIONS FOR PRACTICE Evidence Clinical recommendations rating References If there is diagnostic uncertainty in patients with pruritus, initial C 6-8 evaluation for systemic disease should include thyroid-stimulating hormone, fasting glucose, alkaline phosphatase, bilirubin, creatinine, and blood urea nitrogen levels; complete blood count; and human immunodeficiency virus antibody assay. First- and second-generation antihistamines are equally effective for B 39 resolution of pruritus. A = consistent, good-quality patient-oriented evidence; B = inconsistent or limited-quality patient-oriented evi- dence; C = consensus, disease-oriented evidence, usual practice, expert opinion, or case series. For information about the SORT evidence rating system, go to http://www.aafp.org/afpsort.xml. a substance. It is one of the most common Psoriasis. Up to 80 percent of patients with skin disorders, with a lifetime prevalence psoriasis report pruritus that is cyclical, with of 30 percent.12 Often intensely pruritic, the nocturnal exacerbations that interrupt sleep. dermatitis can be induced by an allergen or Pruritus is often more generalized and not more commonly by an irritant. Irritant con- restricted to areas of psoriatic plaques.16 tact dermatitis represents the most common Scabies. The classic feature of scabies is cause of occupational skin diseases in indus- pruritus, which is caused by deposition of trial countries.13