What could cause a red spot on my hand?

Differential Diagnosis of a Red Spot on the Hand

A red spot on the hand requires systematic evaluation based on occupational exposures, medication history, and clinical characteristics to distinguish between infectious causes (erysipeloid, acute hand infections), inflammatory conditions (hand dermatitis, drug-induced reactions), and systemic diseases.

Key Clinical Features to Assess

Occupational and Exposure History

• Recent handling of fish, marine animals, swine, or poultry suggests erysipeloid, which presents as a red maculopapular lesion on fingers or hands 1-7 days after exposure, with erythema spreading centrifugally and central clearing 1
• Intravenous drug use history (even remote) may indicate Red Puffy Hand Syndrome, presenting as bilateral, painless, non-pitting erythema and edema of dorsal hands 2
• Wet work exposure (healthcare workers, food handlers, cleaners) increases risk for irritant contact dermatitis 3, 4

Medication Review

• Current chemotherapy (5-fluorouracil, capecitabine, doxorubicin, sorafenib, sunitinib) causes palmar-plantar erythrodysesthesia syndrome with redness, swelling, and tingling developing days to weeks after initiation 1
• EGFR inhibitors, MEK inhibitors, or mTOR inhibitors can cause papules, pustules, and erythema on hands 1

Clinical Characteristics to Document

• Single vs. multiple lesions: Solitary red spot with target appearance (blue ring with peripheral red halo) suggests erysipeloid 1
• Pain and tenderness: Painful red spot on fingertip pulp indicates felon (distal pulp infection) 5
• Associated symptoms: Dysesthesia, tingling, or burning pain suggests drug-induced hand-foot syndrome 1
• Bilateral vs. unilateral: Bilateral dorsal hand involvement suggests Red Puffy Hand Syndrome or systemic drug reactions 2

Infectious Causes Requiring Immediate Attention

Erysipeloid

• Treat with penicillin 500 mg four times daily or amoxicillin 500 mg three times daily for 7-10 days 1
• Culture aspirate and/or biopsy establishes diagnosis; blood cultures rarely positive 1
• For penicillin-intolerant patients, use cephalosporins, clindamycin, or fluoroquinolones 1
• Critical pitfall: Erysipelothrix rhusiopathiae is resistant to vancomycin, teicoplanin, and daptomycin 1

Acute Superficial Hand Infections

• Manage with elevation, warm soaks, splinting in position of function, and empiric antibiotics when indicated 5
• Paronychia (nail fold infection): Treat with warm soaks, topical antibiotics, and drainage if abscess present 5
• Felon (distal pulp infection): Requires surgical drainage and empiric oral antibiotics 5

Inflammatory and Dermatologic Causes

Hand Dermatitis (Most Common)

For suspected irritant or allergic contact dermatitis, initiate barrier protection, moisturization, and topical corticosteroids immediately 3

Initial Management Steps

• Identify and avoid irritants: Detergents, frequent handwashing, hot water 3
• Hand hygiene modifications: Use lukewarm water, pat dry gently, avoid disinfectant wipes for routine cleaning 3
• Moisturization protocol: Apply 2 fingertip units of fragrance-free moisturizer with petrolatum or mineral oil to each hand immediately after washing, reapply every 3-4 hours 1, 3
• Topical corticosteroids: Apply when conservative measures fail 3

When to Consider Patch Testing

• Refer to dermatology for patch testing if allergic contact dermatitis suspected or if condition does not improve after 6 weeks of treatment 3
• Occupational exposures requiring evaluation include latex/rubber gloves, preservatives, fragrances in soaps 1, 3

Drug-Induced Hand-Foot Syndrome

For patients on chemotherapy with palmar erythema, continue treatment with oral doxycycline 100 mg twice daily or minocycline 50 mg twice daily for 6 weeks plus topical moderate-strength corticosteroids 1

• Grade 1-2 reactions: Continue drug at current dose with close monitoring 1
• Grade ≥3 reactions: Interrupt drug until symptoms resolve to grade 0-1, consider systemic corticosteroids (prednisone 0.5-1 mg/kg for 7 days) 1

Systemic Disease Manifestations

Red Fingers/Palms Syndrome

• Secondary forms associated with HIV, hepatitis C, hepatitis B, thrombocythemia, or polycythemia vera require treatment of underlying condition 6
• Aspirin effective for myeloproliferative disorders 6
• Manifestations spontaneously regress over months to years 6

Critical Pitfalls to Avoid

• Do not mistake Red Puffy Hand Syndrome for inflammatory arthritis: Elevated rheumatoid factor may be from concurrent hepatitis C, not rheumatologic disease 2
• Do not use vancomycin for suspected erysipeloid: Organism is inherently resistant 1
• Do not apply oil-based moisturizers under latex or rubber gloves: These compromise glove integrity 1
• Do not wash hands with soap immediately before or after alcohol-based hand sanitizer: This increases irritation risk 1, 3
• Do not delay surgical consultation for deep hand infections: Pyogenic flexor tenosynovitis and clenched-fist bite wounds require prompt surgical evaluation 5

When to Refer

• Immediate surgical referral: Deep space infections, felon requiring drainage, pyogenic flexor tenosynovitis 5
• Dermatology referral: Suspected allergic contact dermatitis requiring patch testing, recalcitrant hand dermatitis not responding after 6 weeks, or change in baseline dermatitis pattern 3
• Infectious disease consultation: Suspected tularemia, glanders, or other zoonotic infections 1