A 28-year-old woman from Mumbai presents with a 6-month history of pruritic eczematous lesions on her hands, wrists, and forearms. She works as a healthcare worker and frequently washes her hands with antiseptic soap. On examination, she has erythema, scaling, and fissuring, with sparing of the dorsal web spaces. Her lesions worsen after hand washing and improve with topical emollients. Serum IgE is mildly elevated at 180 IU/mL. Patch testing is planned. What is the most likely diagnosis?

Explanation

## Hand Eczema in a Healthcare Worker: Irritant Contact Dermatitis ### Clinical Presentation Analysis This patient presents with classic features of **irritant contact dermatitis (ICD)**: - **Occupational exposure:** Frequent hand washing with antiseptic soap — the most common cause of ICD in healthcare workers - **Distribution:** Hands, wrists, forearms — precisely the areas exposed to the irritant - **Sparing of dorsal web spaces:** Characteristic of ICD (water and soap pool on the dorsal hand surface, sparing the web spaces due to less contact) - **Morphology:** Erythema, scaling, fissuring — hallmarks of chronic ICD - **Exacerbation with hand washing:** Direct irritant trigger - **Improvement with emollients:** Reflects barrier disruption from repeated detergent/soap exposure **Key Point:** The clinical picture is driven by the **irritant mechanism** — repeated disruption of the stratum corneum by soap and water — not by an IgE-mediated or type IV hypersensitivity mechanism. ### Why Irritant Contact Dermatitis Is the Best Answer 1. **Occupational context:** Healthcare workers are the highest-risk group for ICD due to frequent hand washing. This is well-established in Rook's Textbook of Dermatology and Contact Dermatitis (Johansen et al.). 2. **Sparing of dorsal web spaces:** This is a classic finding in ICD — water and soap accumulate on the dorsal hand but spare the web spaces, producing this distinctive pattern. 3. **Worsening with hand washing, improvement with emollients:** Directly implicates the irritant (soap/water) as the causative agent and barrier dysfunction as the mechanism. 4. **Mildly elevated IgE (180 IU/mL):** A mild IgE elevation is non-specific and does not establish a diagnosis of atopic dermatitis. Normal IgE is <100 IU/mL, but values up to 200 IU/mL can be seen in healthy individuals or in response to environmental allergens. Isolated mild IgE elevation without a personal/family history of atopy, flexural involvement, or childhood onset is insufficient to diagnose AD. 5. **No atopic history provided:** The stem does not mention personal or family history of asthma, allergic rhinitis, or childhood eczema — essential criteria for diagnosing atopic dermatitis (Hanifin & Rajka criteria). 6. **Patch testing planned (not yet positive):** Allergic contact dermatitis (ACD) requires a positive patch test. Until patch testing confirms sensitization, ACD cannot be diagnosed. The clinical pattern (sparing of web spaces, irritant trigger) also favors ICD over ACD. ### Differential Diagnosis Table | Feature | Irritant Contact Dermatitis | Atopic Dermatitis (Hand) | Allergic Contact Dermatitis | Nummular Dermatitis | |---------|-----------------------------|--------------------------|-----------------------------|---------------------| | **Atopic history** | Not required | Yes (essential) | Not required | No | | **Serum IgE** | Normal/mildly elevated | Often elevated | Normal | Normal | | **Patch test** | Negative | Negative | **Positive** | Negative | | **Web space sparing** | **Yes (classic)** | Variable | No (follows allergen) | No | | **Trigger** | Irritants (soap, water) | Irritants + allergens | Specific allergen | Unknown | | **Morphology** | Scaling, fissuring, erythema | Lichenification, flexural | Vesicles, exudation | Coin-shaped plaques | ### Why Other Options Are Incorrect - **Atopic dermatitis with hand involvement (B):** Requires personal/family history of atopy, childhood onset, and flexural involvement. Mildly elevated IgE alone is not diagnostic. The stem provides no atopic history. - **Nummular dermatitis (C):** Presents with coin-shaped (discoid) plaques, not described here. Not associated with occupational irritant exposure or web space sparing. - **Allergic contact dermatitis to soap constituents (D):** Requires a positive patch test (not yet performed). ACD typically follows the exact contact pattern of the allergen and does not spare web spaces. The clinical picture here is more consistent with ICD. **Clinical Pearl:** In healthcare workers with hand eczema, **irritant contact dermatitis** accounts for ~80% of cases. The combination of frequent hand washing, web space sparing, and improvement with emollients is pathognomonic. A mildly elevated IgE does not override this clinical diagnosis. (Reference: Rook's Textbook of Dermatology, 9th ed.; Contact Dermatitis, Johansen et al.) **High-Yield:** For NEET PG — ICD in healthcare workers = frequent hand washing + dorsal hand/wrist involvement + web space sparing + no atopic history required.