Palmoplantar Lichen Planus - Spotter Description

Diagnosis

Definition

Clinical morphology

• Lesions: Well-defined, red-purple to violaceous, scaly plaques, often with marked hyperkeratosis.
• May appear yellowish, compact, callus-like keratotic papules or papulonodules with a faint violaceous hue and peripheral inflammatory halo.
• Usually pruritic. Pain or fissuring can occur in thick plantar lesions.
• Unlike classical lichen planus, lesions are generally not shiny and Wickham striae are usually absent, due to the thickness of palmar and plantar skin.
• Frequently bilateral, though the extent may be asymmetrical.

Sites of predilection

• Palms: Central palm, thenar and hypothenar eminences, and lateral margins of fingers.
• Soles: Medial plantar arch or instep, and margins of the sole.
• Fingertip involvement is uncommon. Its presence should raise the possibility of coexistent hand dermatitis.
• Examine the rest of the skin, oral mucosa, genital mucosa, scalp, and nails for associated lichen planus. About one-quarter of patients have lichen planus at other cutaneous sites, especially shins and malleoli with plantar disease. Fitzpatrick's Dermatology, p. 565.

Clinical patterns

1. Plaque type
   Erythematous-violaceous, scaly, hyperkeratotic plaques. This is the commonest morphology and may mimic palmoplantar psoriasis.
2. Punctate type
   Multiple discrete keratotic papules, often yellowish, on palms or soles.
3. Diffuse keratoderma type
   Diffuse thickening and hyperkeratosis of the palms and/or soles, resembling acquired palmoplantar keratoderma.
4. Ulcerative type
   Painful chronic ulcers or erosions over pressure-bearing plantar areas. This is rare and may be disabling.

Histopathology

• Compact hyperkeratosis
• Wedge-shaped hypergranulosis, though it may be inconspicuous at acral sites
• Irregular acanthosis with “saw-tooth” rete ridges
• Basal-cell vacuolar degeneration or liquefaction degeneration
• Dense, band-like lymphocytic infiltrate at the dermoepidermal junction
• Civatte or colloid bodies
• Max-Joseph spaces

Differential diagnosis

• Palmoplantar psoriasis
• Hyperkeratotic hand or foot eczema
• Acquired palmoplantar keratoderma
• Tinea manuum or tinea pedis
• Verruca vulgaris
• Callosity/corn
• Punctate porokeratosis
• Secondary syphilis
• Lichen simplex chronicus
• Lichenoid drug eruption
• Acrokeratosis paraneoplastica, in appropriate clinical settings

Investigations

• Skin biopsy for confirmation in atypical, isolated, or treatment-resistant lesions.
• Potassium hydroxide examination or fungal culture if dermatophytosis is a possibility.
• Examine oral/genital mucosa and nails for lichen planus.
• Review medications to exclude a lichenoid drug eruption.
• Screen for hepatitis C only where clinically indicated or in accordance with local practice.

Management

• Avoid trauma, friction, and irritants. Use emollients and keratolytics such as salicylic acid or urea for excessive hyperkeratosis.
• First line: Superpotent topical corticosteroid, for example clobetasol propionate, preferably under short-term occlusion for thick lesions.
• Topical calcineurin inhibitors may be useful in selected cases.
• Resistant or extensive disease may require phototherapy or systemic therapy such as a short course of systemic corticosteroids, acitretin, or cyclosporine under specialist supervision.
• Treat associated cutaneous, mucosal, nail, or genital lichen planus as appropriate.

One-line viva answer

1. Plaque type
   Pruritic, well-defined erythematous to violaceous, scaly plaques, with or without hyperkeratosis. May resemble palmoplantar psoriasis.
2. Punctate keratotic type
   Multiple discrete yellowish or hyperpigmented, hard keratotic papules, sometimes with a central depression or plug.
3. Diffuse keratoderma type
   Diffuse thickening and hyperkeratosis of the palm and/or sole, giving a keratoderma-like or callosity-like appearance.
4. Ulcerative type
   Painful erosions or chronic ulcers, more commonly on weight-bearing areas of the soles. It is rare but may significantly impair walking.

Acrosyringeal lichen planus

• Involves the acrosyringium, the intraepidermal portion of the eccrine sweat duct.
• Clinically presents with multiple punctate keratotic papules or pits, often containing central keratin plugs, usually over the palms and sometimes soles.
• May be unilateral or localized.
• It can resemble punctate palmoplantar keratoderma, punctate porokeratosis, arsenical keratoses, warts, or perforating dermatoses.
• Histology demonstrates features of lichen planus with preferential lichenoid inflammation around the acrosyringium. A parakeratotic plug may perforate the epidermis through the eccrine duct.

How to write in an MD answer

1. Diagnosis and morphology

1. What is your diagnosis?
   Palmoplantar psoriasis, hyperkeratotic plaque type, or palmoplantar pustular psoriasis if sterile pustules are present.
2. Describe the lesions.
   Symmetrical, sharply demarcated erythematous hyperkeratotic scaly plaques over palms and soles, often with painful fissures. Pustular disease shows sterile yellow-brown pustules on an erythematous scaly background.
3. What are the types?
   • Hyperkeratotic plaque type
   • Pustular type
   • Mixed plaque-pustular type
4. Why is the condition disabling despite limited body surface area?
   Fissures and hyperkeratosis cause pain, impaired walking, reduced manual work capacity, and marked quality-of-life impairment.

2. Examination questions

1. What will you look for elsewhere?
   • Typical plaques on scalp, elbows, knees, umbilicus, gluteal cleft
   • Nail psoriasis
   • Psoriatic arthritis
   • Mucosal examination is usually not diagnostic but may help exclude other disease
2. Nail changes of psoriasis?
   Pitting, onycholysis, subungual hyperkeratosis, oil-drop/salmon patch, splinter hemorrhages, crumbling.
3. How will you screen for psoriatic arthritis?
   Ask for inflammatory joint pain, morning stiffness, dactylitis, heel pain/enthesitis, inflammatory back pain, and examine peripheral joints, spine, entheses, and digits.
4. What bedside signs of psoriasis can you elicit?
   Grattage test, candle-grease sign, Auspitz sign, and Koebner phenomenon. These may be less demonstrable in thick palmoplantar plaques.

3. Differentials and how to differentiate

1. Differential diagnoses?
   • Hyperkeratotic hand/foot eczema
   • Allergic or irritant contact dermatitis
   • Tinea manuum/tinea pedis
   • Palmoplantar keratoderma
   • Pityriasis rubra pilaris
   • Palmoplantar lichen planus
   • Palmoplantar pustulosis
   • Dyshidrotic eczema/pompholyx
2. Differentiate palmoplantar psoriasis from chronic hand eczema.

1. How will you exclude dermatophytosis?
   Potassium hydroxide mount from scale and fungal culture, particularly in unilateral disease or when there is an active advancing border.
2. Differentiate palmoplantar psoriasis from palmoplantar lichen planus.
   Lichen planus may show violaceous hue, callus-like keratotic papules, typical lesions elsewhere, and histology of a lichenoid interface dermatitis. Wickham striae are often absent on palms and soles.

4. Investigations

1. What investigations will you do?

• Usually clinical diagnosis
• KOH mount and fungal culture to exclude dermatophytosis
• Biopsy if diagnosis is doubtful or refractory
• Patch testing if contact allergy is suspected
• Before systemic therapy: CBC, liver and renal function, lipid profile, viral screening and pregnancy assessment where relevant
• Assess arthritis, obesity, diabetes, hypertension, dyslipidemia, smoking, alcohol use, and depression

1. Histopathology of palmoplantar psoriasis?
   Hyperkeratosis, parakeratosis, regular psoriasiform acanthosis, thinning of suprapapillary plates, reduced or absent granular layer, dilated papillary dermal vessels, Munro microabscesses, and spongiform pustules of Kogoj in pustular lesions.

5. Treatment questions

1. First-line local treatment?

• Emollients
• Keratolytics: salicylic acid or urea
• Superpotent topical corticosteroid, often with short-term occlusion
• Vitamin D analogue, usually in combination with corticosteroid
• Treat fissures with emollients, protective measures, and appropriate dressings

1. What if topical treatment fails?
   Phototherapy, such as localized PUVA or NB-UVB/excimer where available, followed by systemic therapy for severe functional impairment or refractory disease.
2. Systemic drugs used?
   Methotrexate, acitretin, cyclosporine, apremilast, and biologics selected according to disease severity, comorbidities, pregnancy potential, arthritis, local availability, and safety screening.
3. Which systemic drug is useful for hyperkeratotic palmoplantar psoriasis?
   Acitretin is often useful, especially for marked hyperkeratosis or pustular disease. Discuss teratogenicity and lipid/liver monitoring.
4. Counseling points?
   Avoid trauma/friction, use protective footwear and gloves, stop smoking, reduce alcohol excess, optimize weight and metabolic comorbidities, and emphasize adherence because the disease is chronic and treatment-resistant.

6. Pustular disease questions

1. What is palmoplantar pustulosis? Is it the same as palmoplantar pustular psoriasis?
   This is debated. Palmoplantar pustulosis presents with recurrent sterile pustules on palms and soles and is strongly associated with smoking. It may occur with or without plaque psoriasis. Some classifications consider it within the psoriasis spectrum, while others regard it as a distinct entity.
2. What is the association with smoking?
   Smoking is strongly associated with palmoplantar pustulosis. Smoking cessation should be specifically advised.

High-yield closing statement

Differential diagnosis of palmoplantar lichen planus

High-yield exam line