What is the diagnosis and treatment for a patient with a 2-month history of right thumb symptoms, including spontaneous skin peeling and callus formation, severe pain, and no known cause, while wearing non-shared gloves at work?

Diagnosis and Management of Thumb Hyperkeratosis with Progressive Pain

Most Likely Diagnosis

This presentation is most consistent with a mechanical hyperkeratotic callus (clavus) that has progressed to a painful, deep-seated lesion requiring immediate debridement and pressure redistribution. 1, 2

Diagnostic Reasoning

The clinical features strongly suggest mechanical hyperkeratosis rather than infectious or inflammatory pathology:

• Calluses develop as a direct hyperproliferative response of keratinocytes to continuing friction or pressure, appearing as hard, thickened, yellowish areas of skin 1
• The "rock-like" firm yellow appearance with progressive deepening is pathognomonic for chronic mechanical stress 2
• The initial spontaneous peeling followed by callus formation represents the skin's attempt to respond to repetitive trauma, likely from glove-wearing at work 2
• The two-month timeline with progressive worsening and recent severe pain indicates the callus has become deeply embedded 1

Key Differentiating Features

The absence of fever, systemic symptoms, and the localized nature make infectious etiologies less likely:

• Sporotrichosis would typically present with lymphocutaneous spread and multiple nodules along lymphatic channels 3
• Tuberculous dactylitis would show bone destruction on imaging and systemic symptoms 4
• Localized peeling skin syndrome presents with painless superficial peeling without the firm, deep hyperkeratotic component 5, 6

Immediate Treatment Algorithm

Step 1: Physical Debridement (First-Line)

Physical debridement with emery board or nail file can be used for self-management of mild hyperkeratosis, but this case requires professional debridement given the severity and pain 1

• Professional paring down of the hyperkeratotic tissue should be performed to remove the deep-seated callus 1, 2
• Avoid overdebridement of hyperkeratotic lesions, as this makes underlying skin susceptible to increased blistering and tenderness 1

Step 2: Keratolytic Therapy

Apply urea 10-40% cream three times daily to the affected area to soften remaining hyperkeratosis and prevent recurrence 7

• Urea concentrations of 10% or higher are effective for palmar hyperkeratosis 8, 7
• The "soak and smear" technique enhances penetration: soak the thumb in plain water for 20 minutes, then apply urea cream to damp skin 1

Step 3: Pressure Redistribution

The lesions will usually disappear following the removal of the causative mechanical forces 2

• Identify and modify the specific work-related mechanical stress causing the callus 2
• Implement pressure redistribution with cushioning or padding to the affected thumb 7
• Optimize barrier protection with properly fitting gloves that minimize friction 7
• Consider glove modification or rotation of tasks to reduce repetitive pressure 8

Step 4: Anti-inflammatory Therapy (If Inflammatory Component Present)

If there is surrounding erythema or signs of inflammation:

• Initiate clobetasol propionate 0.05% cream or ointment twice daily to affected areas 1
• This is particularly relevant if hyperkeratotic eczema is suspected given the initial peeling phase 1

Critical Pitfalls to Avoid

• Never dismiss this as simple dermatitis without addressing the mechanical cause—the callus will recur without pressure modification 2
• Avoid aggressive blade debridement if there is any suspicion of underlying fragile skin conditions, as this can cause severe complications 7
• Chemical plasters for corn removal should be avoided, especially if the patient has any vascular compromise 7
• Do not assume glove-wearing is protective—poorly fitting gloves can actually cause friction-induced hyperkeratosis 8

When to Refer

Consider referral to dermatology or podiatry if:

• The lesion fails to respond to debridement and keratolytic therapy after 4 weeks 8
• There is concern for underlying bone involvement (order plain radiograph if deep pain persists) 4
• Recurrent lesions despite appropriate pressure modification suggest need for biomechanical assessment 2

Occupational Considerations

Visiting the workplace has an important place in the management of contact dermatitis and mechanical skin conditions 8

• A workplace assessment may identify specific tasks or glove types causing the repetitive trauma 8
• Substitution of glove material or modification of work technique may be necessary 8
• Occlusion by gloves may impair stratum corneum barrier function, potentially contributing to the initial peeling phase 8