Derm Dx: Pruritic papules in a healthy 42-year-old woman

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A 42-year-old Hispanic woman with no prior medical problems presents complaining of multiple pruritic papules and hyperpigmented spots on her arms, trunk and legs.The patient states that the pruritis is frequently worse at night, at times unbearable, but at other times the skin lesions are completely asymptomatic.

On physical exam the patient has multiple firm, small hyperpigmented to slightly violaceous papules and hyperpigmented macules on the dorsal surface of her arms and forearms, on her anterior thighs and on her upper and lower back. There is evidence of excoriations. The lesions spare her central back. Oral and vaginal mucosa is normal.

The patient is unable to identify any alleviating or aggravating factors. The problem started three years ago on her upper arms and has since spread to the aforementioned body areas. In a 14-point review of system, she endorses only pruritis and mild anxiety and denies scratching or picking her skin.

The patient’s family physician recently performed a complete workup, including a physical and gynecologic exam, as well as testing for HIV, hepatitis, fasting blood glucose, renal, liver and thyroid function, all of which were normal. She lives with her elderly mother and two daughters who are all healthy, and she denies tobacco or illicit drug use. What’s your diagnosis?

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Prurigo nodularis, also called "Picker's nodules," is a disease with multiple itching papules and nodules, which usually appear on the extensor surfaces of the arms and legs, but can also involve the trunk. With truncal involvement, the mid-upper back (an...

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Prurigo nodularis, also called “Picker’s nodules,” is a disease with multiple itching papules and nodules, which usually appear on the extensor surfaces of the arms and legs, but can also involve the trunk. With truncal involvement, the mid-upper back (an area where most patients cannot reach) is usually spared. The face, palms and soles are also typically uninvolved. 

Chronic and extensive scratching, picking and rubbing are thought to cause prurigo nodularis. Patients frequently deny manipulating their skin, but on physical exam there is usually evidence of excoriation. Most patients endorse pruritis in the affected areas; however, in rare cases they deny pruritis completely. 

The papules and nodules are generally pea-sized or larger and are frequently excoriated. There is often extensive post-inflammatory hyperpigmentation, as with this case, and superficial scarring. Patients may have several to more than 100 of such papules and nodules.1,2,3

The etiology of the underlying pruritis is frequently idiopathic, as with our patient, however multiple dermatologic and systemic conditions have been associated with prurigo nodularis including atopic dermatitis; xerosis; renal and liver failure; thyroid disease; lymphoproliferative disease; chronic infections such as HIV and hepatitis B and C; and gluten sensitive enteropathy. 1,2,3   

Treatment

The primary treatment goal is to stop the itch-scratch cycle. First-line therapy includes high potency topical steroids, preferably under occlusion, administered in conjunction with anti-itch preparations, such as Sarna lotion and or prepartions that include ingredients such as pramoxine, menthol and phenol. 

Sedating antihistamines such as diphenhydramine hydrochloride (Benadryl, McNeil) or hydrolyzing tricyclic antidepressants such as doxepin are useful, especially in controlling nighttime pruritis. Any underlying systemic disorders should be addressed.

Adjunctive psychotherapy can be helpful, and patients may benefit from selective serotonin reuptake inhibitors, as well as general psychological counseling. Avoiding scratching should be emphasized at each visit. When patients only have several discrete lesions a small piece of corticosteroid-impregnated tape can be placed over each nodule; however this becomes impractical when patients have extensive prurigo. 

Unfortunately, prurigo nodularis can be quite refractory to therapy. In severe cases, phototherapy, cyclosporine or thalidomide may be effective. 1,2,3   

Adam Rees, MD, is a graduate of the University of California Los Angeles School of Medicine and a resident in the Department of Dermatology at Baylor College of Medicine in Houston.

References

1. Bolognia J, Jorizzo JL, Rapini RP. “Chapter 8: Psychocutaneous Diseases.”  Dermatology. 2008: Mosby/Elsevier; St. Louis, Mo.

2. James WD, Berger TG, Elston DM et al. “Chapter 4: Pruritus and Neurocutaneous Dermatoses.” Andrews’ diseases of the skin: Clinical dermatology. 2006: Saunders Elsevier; Philadelphia.

3. Burgin S. “Chapter 15: Nummular Eczema and Lichen Simplex Chronicus/Prurigo Nodularis.” In: Wolff K, Goldsmith LA, Katz SI et al. Fitzpatrick’s Dermatology in General Medicine. 7th ed. 2008: McGraw-Hill; New York. 

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