Dermatology MCQ - Inflammatory Dermatoses - Hand Eczema

A 30-year-old hairdresser presents with a several-month history of a recurrent, intensely pruritic rash on her hands. The rash is characterized by vesicles and scaling on the sides of her fingers and palms. She reports that the flares often occur a day or two after she has been working at the salon. On examination, you note numerous small, deep-seated vesicles on an erythematous base. What is the most likely diagnosis?

A. Allergic contact dermatitis
B. Psoriasis
C. Chronic irritant contact dermatitis
D. Pompholyx (Dyshidrotic eczema)
E. Tinea manuum

Correct Answer: D. Pompholyx (Dyshidrotic eczema)

Explanation:

• The presentation is classic for pompholyx, also known as dyshidrotic eczema. The hallmark features are the presence of intensely pruritic, deep-seated vesicles described as "tapioca pearls" on the lateral aspects of the fingers and palms. It is often chronic and relapsing. While its exact cause is unknown, it is frequently associated with atopy and can be triggered or exacerbated by external factors like contactants, stress, or heat.

• Why the other options are incorrect:

  • A. Allergic contact dermatitis: This would present with a more diffuse, poorly demarcated pattern of erythema, edema, and vesiculation that corresponds to the area of allergen contact (e.g., the entire finger if allergic to a nickel ring, or the dorsum of the hands from gloves). The very specific localization to the sides of the fingers with deep vesicles is less characteristic.

  • B. Psoriasis: Hand psoriasis typically presents as well-demarcated, thick, scaly, erythematous plaques on the palms, or as pustules in the case of palmoplantar pustulosis. It does not feature deep-seated vesicles.

  • C. Chronic irritant contact dermatitis: This is a very common diagnosis in hairdressers due to repeated exposure to water, shampoos, and chemicals. However, it typically presents with dryness, erythema, fissuring, and scaling, predominantly on the dorsum of the hands and finger webs, rather than the classic deep vesicles of pompholyx. It is possible to have both, but the morphology described is specific for pompholyx.

  • E. Tinea manuum: This fungal infection usually presents with a diffuse, dry, scaly plaque on the palm, often in a "one-hand, two-feet" distribution. It does not cause deep-seated vesicles.

Key Points for Exams

• Clinical Features:

  • Acute: Deep-seated, pruritic vesicles on lateral fingers and palms/soles.

  • Chronic: Scaling, erythema, and lichenification after repeated flares.

• Associations: Atopy, emotional stress, and contact allergens (especially nickel) can be triggers. It is crucial to distinguish it from and rule out allergic contact dermatitis with patch testing, particularly in an occupational setting.

• Prognosis: The condition is often chronic and relapsing. Individual flares can last for 2-4 weeks before resolving, often with desquamation.

• Management:

  1. Trigger Avoidance: Identify and avoid irritants and allergens (e.g., wear protective gloves with cotton liners).

  2. Topical Therapy: High-potency topical corticosteroids are first-line for acute flares. Soaks with potassium permanganate or aluminum acetate can help dry oozing vesicles.

  3. Severe/Refractory Cases:

     • Phototherapy: PUVA or NB-UVB can be very effective.

     • Systemic Therapy: Short courses of oral corticosteroids for severe flares. For chronic, recalcitrant cases, steroid-sparing agents like methotrexate, cyclosporine, or mycophenolate mofetil may be used.

     • Biologics: Dupilumab is increasingly used and approved for refractory cases.