Diagnosis | Clinical Features | Ancillary Tests | Initial Therapy |
---|---|---|---|
Tinea Pedis | Onset: 31 to 60 years of age Distribution: Asymmetrical, 4th–5th web space; in-step or “moccasin distribution” Morphology: Fissuring, maceration, herpetiform vesicles, pustules, and bullae with pink base Symptoms: Itch, pain, burning Clinical clues: Concurrent onychomycosis | KOH Preparation or fungal culture | Topical: First-line: Terbinafine 1% cream, butenafine 1% cream, naftifine 1% cream Other: econazole 1% cream Oral: terbinafine 250 mg daily |
Erythrasma | Onset: Increased prevalence with age Distribution: Often involves web spaces of 3rd–5th toes Morphology: Well-marginated pink, brown patches Symptoms: Asymptomatic or mild itch | Illumination with Wood's lamp reveals coral-red fluorescence | Topical: Clindamycin solution, erythromycin gel, or benzoyl peroxide wash Oral:Clindamycin, macrolides, or tetracyclines |
Psoriasis (plaque vs. pustular) | Plaque: Onset: Late teens or 55 to 60 years of age Distribution: Bilateral, symmetric, dorsal, or plantar feet. Morphology: Well-demarcated pink scaly plaques Symptoms: Asymptomatic or painful itch Pustular: Onset: 45 to 65 years of age Distribution: widespread or limited to palms and soles Morphology: Sterile pustules on an erythematous background, fissures Symptoms: Pain, burning, itch Other clues: Nail pitting or distal onycholysis; Pink plaques on the scalp, umbilicus, gluteal cleft, elbows/knees | Clinical diagnosis in most cases Consider biopsy, though it may not be diagnostic | Topical: Mid- to high-potency topical steroids, topical vitamin D analogs (eg, calcipotriene) Systemic: Methotrexate, cyclosporine, acitretin, biologic agents Other: Phototherapy |
Contact Dermatitis Allergic (ACD) Irritant (ICD) | Allergic Contact Dermatitis (ACD): Onset: 8 to 28 days post-exposure Distribution: Symmetrical or asymmetrical, geometric Morphology: Acute: oozing/weeping pink papules, vesicles, and plaques Chronic: dry scaling and fissuring Symptoms: Itch Irritant Contact Dermatitis (ICD): Onset: Minutes to hours Distribution: geometric Morphology: Acute: red indurated plaques, vesicles, ulcers Chronic: dry scaling and fissures Symptoms: Pain and burning | Patch testing (definitive diagnosis for ACD) | Thorough removal of the irritant (for ICD) Avoidance of allergens and irritants Hypoallergenic fragrance-free soaps and emollients Mid- to high-potency topical steroids |
Dyshidrotic Dermatitis | Onset: Recurrent crops in summer and winter Distribution: Symmetrical on the in-step and lateral toes Morphology: 1-mm to 2–mm deep vesicles; “tapioca-like.” Resolution with halo-shaped desquamation and brown circular crusts Symptoms: Severe itch | Clinical diagnosis | Avoidance of harsh soaps and irritants Liberal use of hypoallergenic emollients Mid to high-potency topical steroids |
Juvenile Plantar Dermatosis (JPD) | Onset: Young, school-aged children Distribution: Originating from the base of the big toe, sparing web spaces Morphology: Redness, fissures, scaling, “glazed donut” appearance Symptoms: Itch | Clinical diagnosis | Avoid occlusive footwear and change socks frequently Thick, bland emollients Mid- to high-potency topical steroids |
Abbreviations: ACD, Allergic contact dermatitis; CD, contact dermatitis; DD, dyshidrotic dermatitis; ICD, irritant contact dermatitis; JPD, juvenile plantar dermatosis; KOH, potassium hydroxide; PD, plantar dermatoses; PPP, palmoplantar psoriasis.