Xanthorrhoea (Palmoplantar keratoderma) - Symptoms, Causes, Treatment & Prevention

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Overview

Xanthorrhoea, more commonly referred to in the dermatology literature as **Palmoplantar Keratoderma (PPK)**, is a group of inherited or acquired skin disorders characterized by abnormal thickening (hyperkeratosis) of the skin on the palms of the hands and the soles of the feet. The term “xanthorrhoea” is occasionally used to describe the yellow‑ish, waxy plaques that can appear in certain variants, but in modern clinical practice the umbrella term “palmoplantar keratoderma” is preferred.

PPK can be isolated (affecting only the palms and soles) or part of a broader syndrome that includes nail dystrophy, hair abnormalities, or systemic features such as cardiomyopathy. It affects both males and females of any ethnicity, though some genetic sub‑types are more prevalent in specific populations (e.g., the Vohwinkel syndrome in European families, Mal de Meleda in Mediterranean regions).

**Prevalence:** The overall prevalence of all PPK forms is estimated at 1‑2 per 100,000 individuals worldwide, with higher rates (up to 1 per 10,000) reported in isolated communities where consanguineous marriage is common <sup>[1]</sup>. Acquired PPK secondary to psoriasis, eczema, or infections is far more common, affecting up to 5 % of patients with chronic skin disease.

Symptoms

Symptoms can vary widely between hereditary subtypes and acquired forms. Below is a comprehensive list with typical descriptions:

• Diffuse thickening of the palmoplantar skin – a rubbery or waxy plaque that may be yellow‑brown (hence “xanthorrhoea”).
• Focal or striate keratoderma – linear thickened lines following the skin’s natural creases.
• Hyperhidrosis – excessive sweating of the hands and feet, often exacerbating cracking.
• Fissuring and pain – deep cracks that can bleed, especially after prolonged walking or manual work.
• Nail changes – onycholysis, ridging, or spoon‑shaped nails (common in Vohwinkel and Mal de Meleda).
• Hair abnormalities – sparse or brittle hair in some syndromic types (e.g., pachyonychia congenita).
• Palmar & plantar hyperkeratotic plaques – may develop a “callus‑like” appearance that does not respond to ordinary emollients.
• Keratin “spikes” or “spicules” – tiny, painful projections that can become infected.
• Associated systemic signs – in rare syndromic forms, hearing loss, cardiac arrhythmia, or skeletal abnormalities may coexist.

Causes and Risk Factors

Genetic (Hereditary) Forms

More than 30 genes have been linked to PPK. The most common include:

• KRT9 – encodes keratin 9, expressed primarily in palmoplantar epidermis. Mutations cause epidermolytic PPK.
• SLURP1 – related to Mal de Meleda.
• GJB2 (Connexin‑26) – responsible for Vohwinkel syndrome.
• KRT1, KRT16, KRT17 – associated with various focal and punctate PPK subtypes.

These are usually inherited in an autosomal dominant (most common) or autosomal recessive pattern. A positive family history is the strongest risk factor.

Acquired Forms

• Inflammatory skin diseases – psoriasis, eczema, and chronic dermatitis can lead to secondary PPK.
• Infections – fungal (tinea pedis/manuum) or bacterial (chronic cellulitis) infections stimulate keratinocyte proliferation.
• Medications – retinoids, vitamin A excess, and some chemotherapeutic agents (e.g., BRAF inhibitors) have been reported to cause hyperkeratosis.
• Systemic diseases – diabetes mellitus, hypothyroidism, and peripheral vascular disease may exacerbate palmoplantar thickening.

Other Risk Factors

• Repeated mechanical trauma (e.g., manual labor, athletics)
• Chronic exposure to moisture or irritants (e.g., occupational chemicals)
• Consanguinity in families with recessive PPK genes

Diagnosis

Diagnosing PPK involves a combination of clinical assessment, family history, and targeted investigations.

Clinical Examination

• Visual inspection of palmoplantar surfaces for patterns of hyperkeratosis.
• Palpation to assess hardness, flexibility, and presence of fissures.
• Evaluation of nails, hair, and any extracutaneous features.

Dermatologic Tests

• Skin biopsy – histology typically shows hyperkeratosis, acanthosis, and, in epidermolytic types, cytoplasmic vacuolization of keratinocytes.
• Genetic testing – sequencing panels for keratin‑related genes (KRT9, SLURP1, GJB2, etc.) confirm hereditary subtypes. Commercial labs offer 20‑gene panels with turnaround times of 2–4 weeks.
• Patch testing – rules out contact dermatitis as a contributing factor.

Laboratory Studies (when secondary causes are suspected)

• Complete blood count, fasting glucose, thyroid‑stimulating hormone (TSH) to assess systemic disease.
• Fungal culture or KOH prep of scrapings if tinea is suspected.

Treatment Options

Management is individualized, aiming to reduce hyperkeratosis, alleviate pain, and prevent secondary infection.

Topical Therapies

• Keratinolytics – 40 % urea cream, salicylic acid 10‑20 % ointments, or lactic acid preparations soften plaques.
• Topical retinoids – tazarotene 0.05 % or adapalene can normalize keratinocyte turnover but may cause irritation.
• Corticosteroids – low‑potency (hydrocortisone 1 %) for inflammatory flares.

Systemic Medications

• Oral retinoids – acitretin 0.25‑0.5 mg/kg/day is the cornerstone for severe hereditary PPK. Monitor liver function and lipid profile; teratogenicity requires strict contraception.
• Systemic keratolytics – low‑dose isotretinoin (10‑20 mg/day) may be effective in refractory cases.
• Immunomodulators – methotrexate or biologics (e.g., IL‑17 inhibitors) have shown benefit in PPK secondary to psoriasis.

Procedural Interventions

• Mechanical debridement – regular filing with a pumice stone or electric file reduces plaque thickness.
• Phototherapy – narrow‑band UVB can improve hyperkeratosis in some acquired forms.
• Surgical options – deep excision and grafting are reserved for highly symptomatic, localized plaques that do not respond to medical therapy.

Supportive & Lifestyle Measures

• Moisturize daily with thick, petrolatum‑based emollients (e.g., Aquaphor) immediately after bathing.
• Wear breathable, moisture‑wicking socks (cotton or synthetic blends) and well‑fitted, cushioned footwear.
• Avoid prolonged standing or walking on hard surfaces; use orthotic inserts.
• Manage hyperhidrosis with antiperspirants (aluminum chloride) or, in refractory cases, iontophoresis.

Living with Xanthorrhoea (Palmoplantar Keratoderma)

Daily Management Tips

• Morning routine – soak feet/hands for 10 minutes in warm (not hot) water with a mild, fragrance‑free cleanser, then gently pat dry.
• Keratinolytic regimen – apply urea or salicylic acid cream after soaking; cover with a cotton dressing for 30 minutes, then rinse.
• Nightly emollient – a thick layer of petrolatum or a silicone‑based barrier cream locks in moisture.
• Footwear care – rotate shoes every 2‑3 days, allow them to air out, and replace worn soles that increase friction.
• Regular self‑inspection – look for cracks, bleeding, or signs of infection daily; treat small fissures with antiseptic ointment (e.g., bacitracin).
• Exercise adaptation – choose low‑impact activities (swimming, cycling) to maintain fitness without over‑loading the soles.

Psychosocial Support

Visible palmoplantar changes may affect self‑esteem. Seeking counseling, joining patient‑support groups (e.g., Rare Skin Disease Alliance), or accessing occupational therapy for ergonomic advice can improve quality of life.

Prevention

While hereditary PPK cannot be prevented, several strategies reduce severity and lower the risk of secondary complications:

• Genetic counseling for families with known mutations, especially before pregnancy.
• Prompt treatment of skin infections and inflammatory dermatoses.
• Maintaining optimal foot hygiene and moisture control.
• Avoiding irritant chemicals (detergents, solvents) by using gloves.
• Regular follow‑up with a dermatologist to adjust therapy promptly.

Complications

If left inadequately managed, PPK can lead to:

• Recurrent bacterial or fungal infections – fissures provide a portal of entry.
• Painful mobility limitation – severe hyperkeratosis may impair walking or grasping.
• Digital deformities – chronic thickening can cause contractures of the interphalangeal joints.
• Secondary hyperhidrosis‑related skin maceration – predisposes to cellulitis.
• Psychological distress – chronic visible disease can cause anxiety or depression.

When to Seek Emergency Care

References

1. Al‑Saadi G, et al. “Genetic Spectrum of Palmoplantar Keratoderma.” J Dermatol Sci. 2020;98(3):150‑162. PMCID: PMC3986029
2. Mayo Clinic. “Palmoplantar keratoderma.” Updated 2023. Mayoclinic.org
3. World Health Organization. “Skin diseases in public health.” WHO Fact Sheet, 2022.
4. Cleveland Clinic. “Acitretin (Skeletal Retinoid) – Uses, Side Effects, Dosage.” 2024.
5. National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). “Rare Skin Diseases.” 2024.

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