What is the appropriate diagnosis and treatment for itching of palms and soles with lacerative lesions?

Diagnosis and Management of Itching Palms and Soles with Lacerative Lesions

The most likely diagnosis is palmoplantar psoriasis or hyperkeratotic hand eczema, which should be treated initially with high-potency topical corticosteroids (clobetasol 0.05% twice daily) combined with urea 10% cream three times daily, while ruling out life-threatening causes like Rocky Mountain spotted fever if fever is present. 1, 2

Immediate Life-Threatening Exclusions

Before proceeding with routine dermatologic management, you must first exclude conditions with significant mortality:

• If fever, headache, or systemic symptoms are present with recent tick exposure: Treat empirically with doxycycline immediately for Rocky Mountain spotted fever, which presents with maculopapular rash involving palms and soles 2-4 days after fever onset and carries 5-10% mortality if untreated. 3, 1
• Do not wait for the classic triad (fever, rash, tick bite) before treating suspected RMSF—only a minority present with all three initially, and delayed treatment increases mortality. 1
• If pregnant with pruritus: Measure serum bile acids to exclude intrahepatic cholestasis of pregnancy, which predominantly affects palms and soles, is worse at night, and confers risk of stillbirth. 3

Differential Diagnosis of Palmoplantar Hyperkeratosis with Itching

The most common causes in order of frequency are:

1. Palmoplantar psoriasis (40% of cases): Well-demarcated erythematous plaques with thick silvery scale and hyperkeratosis. 2, 4
2. Hyperkeratotic hand-foot eczema (31% of cases): Vesicles, scaling, erythema, and fissuring with yellow-white scaling on dermoscopy. 2, 4
3. Tinea pedis/manuum: Requires KOH examination and fungal culture for confirmation. 5
4. Pustulosis palmaris et plantaris: Sterile pustules on erythematous base. 5

Diagnostic Approach

History must include:

• Onset timing, diurnal variation (worse at night suggests cholestasis in pregnancy), aggravating factors. 6
• Occupational exposures to irritants or allergens (frequent hand washing, chemicals, wet work). 2
• Recent tick exposure or travel (RMSF consideration). 3, 1
• Pregnancy status (cholestasis consideration). 3
• Chemotherapy history (hand-foot syndrome from capecitabine, 5-FU, doxorubicin, sorafenib). 1

Physical examination must assess:

• Presence of true rash versus excoriations from scratching (cholestasis has no primary rash, only excoriations). 3
• Distribution pattern: Psoriasis shows regularly arranged dots and globules on dermoscopy; eczema shows yellow-white scaling. 4
• Look for transgrediens (extension beyond palmar/plantar skin). 7

Laboratory evaluation:

• KOH preparation and fungal culture if tinea suspected. 5, 4
• If no skin disease evident: Complete blood count, liver function tests, serum creatinine, thyroid-stimulating hormone, chest X-ray to exclude systemic causes (cholestasis, thyroid disease, polycythemia, Hodgkin disease, HIV). 8
• Serum bile acids if pregnant with pruritus. 3

First-Line Treatment Algorithm

For palmoplantar psoriasis or hyperkeratotic eczema:

1. Topical therapy (initiate simultaneously):

   • Clobetasol propionate 0.05% cream or ointment twice daily to affected areas. 2
   • Urea 10% cream three times daily to all affected areas, including after hand washing, for humectant and keratolytic effects. 2
   • Use "soak and smear" technique: Soak hands in plain water for 20 minutes, then apply moisturizer to damp skin to enhance penetration. 2

2. Behavioral modifications (mandatory):

   • Minimize hand washing frequency; use lukewarm water (avoid >40°C). 1, 2
   • Apply moisturizer after every hand wash. 1
   • Wear protective gloves for wet work with moisturizer underneath. 2
   • Avoid mechanical stress; wear cushioned gloves for activities involving friction. 2

Second-Line Treatment for Refractory Cases

If no response after 4 weeks of topical therapy:

• Refer for topical PUVA (psoralen plus UVA) therapy 2-3 sessions weekly, which achieves clearance or considerable improvement in 58-81% of dyshidrotic eczema and 50-67% of hyperkeratotic eczema. 2
• Alternative: 308-nm excimer laser for targeted phototherapy. 3

Third-Line Systemic Therapy

For severe disease with significant quality of life impairment:

• Initiate acitretin 25 mg daily for palmoplantar psoriasis, which demonstrates significant improvement in scaling, thickness, and erythema within 2 months. 3, 2
• Monitor lipid panels; elevations in triglycerides and cholesterol are common but manageable with fibrates or statins. 3, 2
• Alternative systemic options: Methotrexate or cyclosporine, though hepatotoxicity, bone marrow toxicity, and nephrotoxicity must be considered. 3

Critical Pitfalls to Avoid

• Never dismiss fever with palmar rash as simple dermatitis—RMSF mortality increases dramatically with delayed doxycycline treatment. 3, 1
• Do not confuse excoriations from scratching with primary rash—cholestasis in pregnancy has no primary rash, only secondary excoriations. 3
• Histopathology is often necessary for definitive diagnosis—four out of 19 histopathologically confirmed eczema cases showed clinical and dermoscopic features of psoriasis in one study, highlighting diagnostic overlap. 4
• Dermoscopy aids diagnosis but does not replace biopsy when clinical uncertainty exists, especially given the morphological similarity between conditions. 4