23 - NUMMULAR ECZEMA, LICHEN SIMPLEX CHRONICUS AND PRURIGO NODULARIS Flashcards
Nummular eczema:
■ Also known as nummular dermatitis and discoid eczema.
■ A chronic inflammatory skin disorder of unknown etiology.
■ Papules and papulovesicles coalesce to form nummular plaques with oozing, crust, and scale.
■ Most common sites of involvement are upper extremities in men and women, particularly the dorsal hands in women, and the lower extremities in men.
■ Pathology may show acute, subacute, or chronic eczema.
Lichen simplex chronicus
■ A chronic, severely pruritic disorder characterized by one or more lichenified plaques.
■ Most common sites of involvement are scalp, nape of neck, extensor aspects of extremities, ankles, and anogenital area.
■ Pathology consists of hyperkeratosis, hypergranulosis, psoriasiform epidermal hyperplasia, and thickened papillary dermal collagen.
Prurigo nodularis
■ Also known as prurigo, picker’s nodules, or nodular prurigo of Hyde.
■ A pruritic disorder that runs a chronic course.
■ Hyperkeratotic firm nodules vary in size from 0.5 to 3.0 cm and may be excoriated.
■ Associations include atopic dermatitis and systemic causes of pruritus.
■ Pathology consists of hyperkeratosis, hypergranulosis, psoriasiform epidermal hyperplasia, thickened papillary dermal collagen, and characteristic neural hypertrophy.
morphologic term to describe coin-shaped plaques that may have multiple etiologies
Nummular eczema or discoid eczema
CLINICAL FINDINGS OF NUMMULAR ECZEMA
Well-demarcated, coin-shaped plaques form from coalescing papules and papulovesicles. Often, studded or satellite papulovesicles appear at the periphery of an expanding central plaque and should not be confused with the satellitosis present in fungal or yeast infections. Pinpoint oozing and crusting eventuate, and are distinctive (Figs. 23-1 and 23-2). Crust may, however, cover the entire surface (Fig. 23-3). Plaques range from 1 to >3 cm in size. The surrounding skin is generally normal, but may be xerotic and/or have asteatotic eczema lesions. Pruritus varies from minimal to severe and may be worse in the evening and during periods of relaxation. Central resolution may occur, leading to annular forms. Chronic plaques are dry, scaly, and lichenified. The classic distribution of lesions is the extensor aspects of the extremities, particularly the lower extremities. 7,10 Onset of nummular eczema peaks in the winter and troughs in the summer.
SPECIAL TESTS
Patch testing is indicated in chronic recalcitrant cases to rule out underlying contact dermatitis. Previous studies found a variety of relevant positive allergens in patch testing, including nickel, chromates, and other metals; rubber; fragrances, formaldehyde, and other preservatives commonly found in cosmetics and personal care products; neomycin and other topical medicaments; and colophony.6,10,20
Skin biopsy and histopathologic examination may be needed to rule out other clinical entities, such as autoimmune blistering disorders and cutaneous T-cell lymphoma. Histopathologic changes are reflective of the stage at which the biopsy is performed. Acutely, there is spongiosis, with or without spongiotic microvesicles. In subacute plaques, there is parakeratosis, scale crust, epidermal hyperplasia, and spongiosis of the epidermis (Fig. 23-4). There is a mixed cell infiltrate in the dermis. Chronic lesions may resemble lichen simplex chronicus microscopically.
Differential Diagnosis of Nummular Eczema
COMPLICATIONS
Nummular eczema may be complicated by profound sleep disturbance owing to intense itch and secondary bacterial infection.
phenotypes that are caused by repeated itching, scratching, and rubbing of the skin
LICHEN SIMPLEX CHRONICUS/PRURIGO NODULARIS
They can be associated with multiple etiologies of dermatologic and/or systemic disease. 35 However, some use these terms (LSC and PN) to describe a specific diagnosis, which excludes other dermatologic disorders that present with these lesions, such as AD (ie, nodular prurigo of Hyde). 36,37 The epidemiology of LSC and PN is not well-defined, owing to scant studies and the different definitions used in the studies. Little is known about the descriptive epidemiology of PN. A retrospective population-based study in Taiwan found the incidence of LSC to be 25 to 28 versus 17.8 per 10,000 person-years in those with versus those without a history of anxiety disorders. 38 A cross-sectional study found that LSC and PN were encountered in 3% and 2.1% of dermatology visits, respectively. 9 PN more commonly occurs in adults, but can occasionally affect children. 9,39,40 Patients with PN in the setting of AD have been found to have an earlier age of onset as compared to those without AD. 41 LSC may be more common in patients of Asian descent for reasons unknown.
HISTORY TAKING IN LSC AND PN
Severe itching is the hallmark of LSC and PN. Itching may be paroxysmal, continuous, or sporadic, localized or diffuse. Itching may be described by patients as burning, stinging, or a creepy-crawly sensation akin to formication. Patients may not be aware of itching and scratching that occurs during sleep time. Patients may also develop habitual scratching or picking of lesions, even when they are not itchy. Itch is often triggered by sweating, heat, friction, extreme humidity or dryness, irritation from personal care products or clothing, and/or times of psychological distress. 53,54 LSC and PN are associated with moderate to severe quality-of-life impairment 74-77and sexual dysfunction.
CUTANEOUS LESIONS OF LSC/PN
In LSC, repeated rubbing and scratching gives rise to lichenified, dry, and scaly plaques with or without excoriations. Hyperpigmentation and hypopigmentation can be seen, particularly in patients with skin of color. The most common sites of involvement are the scalp, the nape of the neck, the ankles, the extensor aspects of the extremities, and the anogenital and vulvar regions. 79 The labia majora in women and the scrotum in men (Fig. 23-5) are the most common sites of genital involvement. 45 The upper inner thighs, groin, nipple, and areola also may be affected.79
firm to hard on palpation, varying in size from 0.5 cm to >3.0 cm, and numbering from few to hundreds
Prurigo nodules
The surface may be hyperkeratotic or crateriform. There is often overlying excoriation. Pruritus is usually severe. Limbs are affected in most cases, especially the extensor aspects (Fig. 23-6). The abdomen and sacrum were the next most common sites of involvement in one study. 39 Face and palms are rarely involved. Nodules may occur on any site that can be reached by the patient. There can be a characteristic “butterfly sign” with lesional sparing on the upper back. However, some patients may even develop nodules on hard-to-reach areas secondary to using backscratchers, knives, forks, brushes, or other instruments to scratch. Nodules may persist for months to years and resolve with postinflammatory hyperpigmentation or hypopigmentation and scarring.
Differential Diagnosis of Lichen Simplex Chronicus
COMPLICATIONS OF LSC/PN
Sleep studies show that disturbances in the sleep cycle in LSC are present. Non-rapid eye movement sleep is disturbed and patients have an increased arousal index (brief awakenings from sleep) caused by scratching.81
Patients with LSC and PN have higher rates of depression, anxiety, obsessive-compulsive disorder, and other psychological disorders.39,63-67
A retrospective population-based cohort study found that patients with LSC had higher baseline rates of diabetes, hypertension, hyperlipidemia, cardiovascular disease, peripheral arterial disease, chronic kidney disease, depression, and anxiety, and an increased risk of developing erectile dysfunction.
Most common sites of involvement of nummular eczema
upper extremities in men and women, particularly the dorsal hands in women, and the lower extremities in men.
Stepwise management of prurigo nodularis and lichen simplex chronicus
- In both conditions, first-line measures to control itch include potent topical corticosteroids as well as nonsteroidal antipruritic preparations such as menthol, phenol, or pramoxine.
- Emollients are an important adjunct, particularly for those patients with AD.
- Intralesional steroids, such as triamcinolone acetonide, given in varying concentrations according to the thickness of the plaque or nodule are beneficial.
- Topical tacrolimus has been successfully employed as a steroid-sparing agent, but may require application under occlusion to improve transcutaneous absorption.
- Sedating antihistamines, such as hydroxyzine, or tricyclic antidepressants, such as doxepin, may be used to abolish nighttime itch in both conditions.
