How To Handle Common Skin Dermatoses

Author(s): 
By James Q. Del Rosso, DO, FAOCD

Dermatoses of the lower extremities are fairly common.1 These conditions include infectious, inflammatory, vascular, neoplastic and traumatic dermatoses. Many dermatologic conditions (i.e. psoriasis, lichen planus) that exhibit the potential for widespread distribution can be prone to occur on the legs, ankles or feet in some patients. Other disorders characteristically involve the lower extremities. For example, dyshidrotic eczema and pitted keratolysis are examples of dermatoses that involve the plantar surface of the foot.
With this in mind, let’s take a closer look at these conditions and the appropriate treatment regimens for each.

Diagnosing And Managing Pitted Keratolysis
Pitted keratolysis is a superficial bacterial infection that involves the weightbearing regions of the plantar surface and usually affects both feet.2 You’ll find that young adults and children are most often affected by this condition.3 Several keratinase-producing bacteria (including Corynebacterium spp, Micrococcus sedentarius and Streptomyces spp) have been implicated.1,4

These patients often have a “soggy stratum corneum” caused by prolonged exposure of the feet to closed, moisture-impermeable shoes and sweaty socks. Superficial maceration and plantar hyperhidrosis are commonly associated features. Keep in mind that this disorder is often misdiagnosed and erroneously treated as tinea pedis.
Another plantar disorder associated with hyperhidrosis is symmetrical lividity. This entity, which predominantly affects young adult males, presents as sweaty or macerated anterior and posterior soles.1,5 Unlike pitted keratolysis, plantar symmetrical lividity demonstrates a macular, purplish-red livedo-like appearance. However, be aware that pitted keratolysis and symmetrical lividity may coexist in the same patient.5
Pitted keratolysis is asymptomatic, but is often associated with malodor. The clinical features are usually always diagnostic, presenting as multiple, shallow, round or oblong, punched out-appearing depressions. The etiologic bacterial organisms are not easily cultured using standard media, but you may be able to identify them in routinely stained, formalin-fixed histologic sections of shaved stratum corneum.2 Since the clinical features are so distinctive, laboratory diagnostic testing is not needed.

The primary goals of therapy for pitted keratolysis are: (1) promotion of dryness; (2) control of hyperhidrosis; (3) minimized exposure to occlusive footwear; (4) improved hygience; and (5) eradication of bacterial overgrowth.2,4
Nightly application of aluminum chloride 20% solution is very effective. The drying effect of topical aluminum chloride may be significant enough to warrant using an emollient in the morning to prevent symptomatic irritation, chafing and fissuring. Having patients apply topical clindamycin phosphate 1% or erythromycin 2% (solution or gel) twice a day until they achieve clearance is very effective.2-4 Alcohol-based formulations of benzoyl peroxide 6–10% can be used as a cleanser. The “leave on” gel is also effective.2 It is important to inform the patient that benzoyl peroxide, specifically when it is used with a “leave on” gel, may bleach color from fabric (i.e. colored socks).
For long-term control of underlying chronic hyperhidrosis, you may emphasize intermittent use of topical aluminum chloride 20% solution, usually one to three nights per week, or topical aluminum chloride 6.25% solution, which is applied more frequently (i.e. nightly, every other night) to maintain control of pedal sweating.

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