The Hands

Hand eczema is a very special problem because there is commonly more than one cause for the eruption. Contact dermatitis of the hands is often irritant with dry scaly patches, which in some atopics are converted to a discoid eczema. Dermatitis under a ring is usually an irritation from soap. Occupational factors are important because persons handling raw meat (e.g., slaughterhouse, chicken processing and fishery workers, butchers and chefs), those engaged in wet work, and mothers with small children are particu-

Fig. 6. Six-year-old girl with contact dermatitis to shoes. She reacted to potassium dichromate on patch testing, suggesting leather as a source.
Fig. 8. Eczema that seems to spread where an ointment or lotion is applied suggests sensitivity to a medication. Patch testing was positive to neomycin, which was a component of the cream the patient had applied.

larly vulnerable. Another often unsuspected cause is in mechanics, machine repairmen, and so forth, who try to remove insoluble metal dust, carbon, and rubber dust with soap and abrasives, irritating the skin in the process. Often a nonsensitizing cream will remove such materials without irritation. Allergic contact dermatitis is covered in the section on regional contact dermatitis.

Persons with a nummular or discoid pattern (Fig. 10) are often atopic individuals. Sometimes women who had atopic eczema as children but who have enjoyed a prolonged remission break out anew from the stress of wet work and irritant exposure with the rearing of children.

Dyshidrotic eczema, or pompholyx (Fig. 11), is identified morphologically by its deep-seated single vesicles (at least initially) and the tendency for the vesicular eruption to form an apron pattern. It is commonly a dermatophytid, but systemic contact dermatitis, stasis eczema with id, infectious eczematoid dermatitis, nummular eczema, and other causes can often be found if one looks carefully. Some cases are, however, idio-pathic.

Hyperkeratotic hand eczema may occur from contact dermatitis. When it does, it is often difficult to know whether one is faced with one or more than one condition. Perhaps the main things to rule out are certain skin diseases that characteristically occur in areas of trauma. This is often called the Koebner phenomenon in psoriasis, lichen planus, and the like. On the fingers and palms, psoriasis is often misdiagnosed as eczema because it is located in areas of contact such as the thumb and index and middle fingers, along with fictional areas of the palms. Psoriasis in this location usually does not itch, it fissures in winter, and it is usually associated with other findings characteristic of psoriasis, such as pitting of the fingernails, onycholysis, and lesions of the elbows, knees, and scalp (espe-

Fig. 9. Depigmentation following a reaction to ear drops containing neomycin. This patient was allergic to multiple aminoglycosides but not to streptomycin, which lacks the 2-deoxystreptamine ring.

cially in the nuchal area) and in the intergluteal fold. A positive family history should make one suspicious, but it is often negative. Lichen planus can also be located on the hands. Lesions of that disease elsewhere are usually more typical in morphology, and, unlike most cases of psoriasis, a biopsy can be helpful. Certain drugs are often aggravating factors in psoriasis and lichen planus and may be the cause of the latter.

Lesions on the hands (and feet) can also be caused by infectious and parasitic conditions, including dermatophytosis, scabies, and herpes simplex, which can all on occasion mimic contact reactions. The morphology and distribution help, and a potassium hydroxide (KOH), Tzanck test, and/or culture will confirm the diagnosis.

On the hands, allergic contact dermatitis is suspected especially when the grip and frictional areas of the palms are involved, but patch testing can be justified in most patients with hand eczema, as it helps establish the cause. A glove-like pattern is a giveaway for glove dermatitis. This is usually a reaction to rubber, but it can also be caused by leather and other materials. Occupational patterns (Fig. 12) are often seen in the grip areas of the fingertips in florists and are a result of Alstroemeria—in chefs from

Table 1

Differentiating Allergic and Irritant Contact Dermatitis3

Table 1

Differentiating Allergic and Irritant Contact Dermatitis3

Allergic

Irritant

Appearance

Redness, vesicles,

Redness, chapping, scaling,

papules, oozing,

fissures, pustules

crusting, lichenification

Population involved

Sensitive individuals

Anyone with adequate

(only one person at

dosage (many doing the

this job)

same job)

Onset following

Varies with location

Minutes to hours,

exposure

(usually days)

but may be cumulative

Require for previous

Yes

No

exposure

Dose dependency

Less

More

Dilution tends to

abolish the reaction

Typical symptoms

Itching

Burning, pain

Localization

May spread beyond

Often sharply marginated,

of patch test

application site after

limited to occluded area

response

removal of chamber

Patch test, relevance

Positive and

Negative or positive

relevant

and not relevant

  • Irritant and allergic reactions often coexist and can be difficult to reliably separate clinically or histologically. The criteria given are commonly used in evaluating patch test responses, but they are not absolute.
  • Irritant and allergic reactions often coexist and can be difficult to reliably separate clinically or histologically. The criteria given are commonly used in evaluating patch test responses, but they are not absolute.

garlic, in hairdressers from glyceryl monothioglycolate in acid perms, and in industrial workers due to epoxy and other adhesives, for example. Sometimes a pattern can suggest a source, as with liquid soaps, which cause an eczema of the finger webs extending onto the palm at the base of the middle and adjacent fingers. Sometimes the contact dermatitis alters the appearance of the original condition, such as the fingertip eruption one sees from shampoo (which may be irritant or allergic) or the spreading eczema that occurs from reactions to medications. A diffuse dermatitis of the dorsum sparing protected areas may be light induced. Remember, however, even typical presentations require patch-test confirmation.

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