Clinical clues important for accurate diagnosis in the elderly

Asteatosis is the most common cause of itching in older patients and may be generalized, although it is usually most prominent on the legs and arms. Severe asteatosis on the lower extremities can be accompanied by significant edema and erythema that can lead to a misdiagnosis of cellulitis.

"Patients with asteatosis are afebrile and will have involvement of both legs, while cellulitis does not occur bilaterally and the affected patient will be ill, presenting with fever and flu-like symptoms. Those features can be used as a tip-off that the patient does not have an infection," Dr. Miller says.

"Interestingly, these patients may have no involvement of the skin on the distal foot or right above the ankles where there has been pressure from the shoes or elastic in the socks," Dr. Miller notes.

Asteatotic eczema develops in older persons because the free fatty acid content in the stratum corneum decreases with age. The arms and legs are at greater risk for developing asteatosis due to the relatively lower concentration of sebaceous glands in the skin on the extremities. Low humidity and heat aggravate the condition, which is why patients present most often in the fall and winter when the heat comes on and the long underwear comes out, Dr. Miller says.

Since exposure to soap and water worsens dry skin by removing the natural oils, patients should be counseled to bathe or shower quickly, avoid soap and use a syndet (e.g., Dove, Cetaphil) instead of soap to cleanse the noninvolved areas only.

However, "soak and smear" represents an alternative approach to treatment. In that technique, the patient is directed to hydrate the stratum corneum by soaking in a tub of plain water for about 20 minutes at bedtime. Immediately after getting out of the bath, the skin is smeared with a corticosteroid ointment.

Petrolatum alone may be used instead of a steroid to improve skin hydration if there is not significant inflammation. If the itching is more severe, a topical corticosteroid can be used under occlusion. As alternatives to Saran Wrap, a hydrocolloid dressing can be used to occlude limited areas of involvement. An Unna boot is often used, especially in nursing home patients.

"After one or two days of occlusion and compression for the edema, the legs are usually clear," Dr. Miller says.

Rare scalp disorder

Erosive pustular dermatosis of the scalp appears as an area of scale, crust, pustular erosion and granulation tissue that can lead to scarring alopecia. This rare entity occurs more often in older women than in men and may be misdiagnosed as an infection and treated with antibiotics or as a cutaneous malignancy, which may be subjected to inappropriate surgery.

However, it is important to avoid unnecessary surgery because erosive pustular dermatosis develops as an excessive inflammatory response to local injury.

"The history in these patients may reveal an accidental bump on the head as the precipitating trauma, or they may have had a dermatologic procedure for treatment of an actinic keratosis or basal cell carcinoma," Dr. Miller says.

A beefy red appearance of the persistent granulation tissue suggests the diagnosis of erosive pustular dermatosis. Treatment consists of application of a class I topical corticosteroid or intralesional steroid injection. When treating topically, the exuberant granulation tissue may be first curetted away.