What is the diagnosis and treatment for an adult with a history of manual labor, presenting with a 2-month history of right thumb symptoms including skin peeling, callus formation, and severe pain?

Diagnosis and Management of Thumb Hyperkeratosis with Progressive Pain

This presentation is most consistent with a focal hyperkeratotic lesion (callus) that requires immediate professional debridement, but you must first rule out an infectious process given the severe pain, progressive worsening, and occupational exposure.

Differential Diagnosis

The clinical presentation of spontaneous skin peeling followed by thick, firm, yellow hyperkeratotic growth with severe pain suggests several possibilities:

Most Likely: Focal Hyperkeratosis (Callus)

• Calluses develop as a hyperproliferative response of keratinocytes to continuing friction or pressure, appearing as hard, thickened, yellowish areas of skin 1
• The occupational history of manual labor with glove use strongly supports mechanical trauma as the underlying cause 2
• Progressive deepening and pain indicate significant keratin accumulation requiring intervention 3

Critical Rule-Outs Before Treatment

You must exclude infectious etiologies before proceeding with debridement:

• Tuberculous dactylitis can present as progressive thumb swelling with pain after trauma, showing extensive bone destruction on imaging 4
• Nocardia infections present as subcutaneous nodules or abscesses that are frequently painless and "cold to the touch," but can cause progressive symptoms 5
• Fungal infections (Aspergillus, Fusarium) can present as nodules or ulcers in the skin, particularly with occupational exposure 5

If fever, systemic symptoms, or constitutional signs are present, initiate immediate evaluation for infectious causes including imaging and possible biopsy 1

Diagnostic Approach

Immediate Assessment

• Paring down the lesion is diagnostic: calluses maintain preserved skin lines and show uniform yellow keratin, while warts expose elongated dermal papillae with pinpoint bleeding 3
• Assess for systemic symptoms (fever, malaise, weight loss) that would suggest infection 5, 1
• Plain radiograph of the thumb to exclude underlying bone involvement or pathological changes 4

Physical Examination Findings

• Calluses present as hard, thickened, yellowish areas at pressure points with preserved skin lines 3
• The "rock-like" firmness and yellow color are characteristic of significant hyperkeratosis 1
• Severe pain suggests either deep keratin accumulation with pressure on underlying structures or possible infection 5, 1

Treatment Algorithm

If Infectious Etiology is Excluded:

Professional debridement is the primary treatment and should be performed immediately given the severe pain:

• Manual debridement using blade or scalpel by a trained provider (podiatrist or dermatologist) removes the thickened keratin effectively 3
• Conservative approach is critical: avoid overdebridement as this makes underlying skin susceptible to increased blistering and tenderness 5, 1
• After debridement, apply emollients and non-adherent dressings to protect the debrided skin 5

Adjunctive Topical Therapy

• Apply urea-based keratolytic creams (10% urea cream) daily to maintain skin barrier and reduce keratin thickness 2, 1
• The "soak and smear" technique enhances penetration: soak hands in plain water for 20 minutes, then apply moisturizer to damp skin 1

Pressure Redistribution

• Modify work practices to reduce mechanical stress and friction on the thumb 2
• Consider protective padding or modified glove use to prevent recurrence 5, 2
• Assess weight distribution and pressure points during occupational activities 5

Maintenance Management

• Self-management with emery board or nail file after soaking in warm water can maintain results between professional treatments 3, 1
• Continue urea-based emollients to prevent reformation 2, 1

Critical Pitfalls to Avoid

• Never dismiss severe pain as simple callus—progressive worsening with deep extension warrants imaging to exclude tuberculous dactylitis or other infectious processes 4
• Avoid overdebridement, which makes underlying skin susceptible to increased blistering and tenderness 5, 1
• Do not attempt aggressive self-debridement given the severity and depth of the lesion 3
• If the lesion does not respond to standard debridement or continues to worsen, refer for specialist evaluation and consider biopsy 5, 4

When to Refer

Immediate referral to dermatology or hand surgery if:

• Imaging reveals bone involvement 4
• Systemic symptoms develop 5, 1
• No improvement after professional debridement 3
• Concern for malignancy (squamous cell carcinoma can present as hyperkeratotic lesions) 3