Dermatology MCQ - Inflammatory Dermatoses - Asteatotic eczema

An 82-year-old woman presents in the winter months with a several-week history of intensely pruritic skin changes on her shins. On examination, the skin of her lower legs appears dry and scaly, with a distinctive network of superficial, red fissures creating a pattern reminiscent of a cracked porcelain plate. There is no significant edema, ulceration, or evidence of venous disease. What is the most likely diagnosis?

A. Stasis dermatitis
B. Plaque psoriasis
C. Tinea corporis
D. Asteatotic eczema
E. Allergic contact dermatitis

Correct Answer: D. Asteatotic eczema

Explanation:

• The description is classic for asteatotic eczema, also known as eczema craquelé. It is characterized by dry skin (xerosis) that has fissured, creating a polygonal or "crazy-paving" pattern. It occurs when the skin's natural lipids and moisture are depleted, a common scenario in the elderly due to reduced sebaceous gland activity and frequent bathing in hot water, particularly during the low-humidity winter months.

• Why the other options are incorrect:

  • A. Stasis dermatitis: While it also commonly affects the lower legs, it is associated with signs of chronic venous insufficiency, such as edema, varicose veins, hemosiderin deposition (brown discoloration), and often medial ankle involvement. The primary finding here is the distinctive cracking pattern, not venous changes.

  • B. Plaque psoriasis: Presents as well-demarcated, thick, erythematous plaques with adherent silvery scale. It does not typically present with a widespread, fine, cracked pattern.

  • C. Tinea corporis: Appears as an annular, expanding plaque with a raised, scaly, and often vesicular border and central clearing. The diffuse, non-annular, cracked pattern on both shins is not consistent with a fungal infection.

  • E. Allergic contact dermatitis: Usually presents with more acute erythema, vesiculation, and edema in a distribution that corresponds to exposure to an allergen. The symmetric, dry, cracked appearance is not typical.

Key Points for Exams

• Pathophysiology: Results from severe dehydration of the stratum corneum, leading to shrinkage and fissuring of the skin surface.

• Predisposing Factors: Advanced age, low ambient humidity (winter, desert climates, central heating), frequent hot bathing, use of harsh soaps, and diuretic medications.

• Location: Most common on the lower legs, but can also affect the arms, thighs, and trunk.

• Prognosis: Excellent. It is a condition that responds very well to simple, consistent emollient therapy and avoidance of aggravating factors. It usually resolves within a few weeks with proper treatment.

• Management:

  1. Emollients: The cornerstone of treatment. Thick, occlusive ointments (e.g., petrolatum) or rich creams should be applied immediately after bathing to trap moisture.

  2. Avoidance of Aggravants: Recommend using lukewarm (not hot) water for bathing, limiting bath/shower duration, and using mild, non-detergent, soap-free cleansers.

  3. Humidification: Using a humidifier in the home, especially in the bedroom, can be very beneficial.

  4. Topical Corticosteroids: For the inflamed, pruritic phase, a short course of a low- to mid-potency topical corticosteroid can be used to rapidly reduce inflammation and itching. However, the mainstay of long-term control remains effective moisturization.