What could be causing itchiness on my wrists and ankles, along with a dry scaly rash on my left upper eyelid?

Differential Diagnosis: Contact Dermatitis with Possible Systemic Evaluation

You most likely have allergic contact dermatitis affecting your wrists, ankles, and eyelid, and should be patch tested by a dermatologist to identify the specific allergen causing your symptoms. 1, 2

Primary Diagnosis: Allergic Contact Dermatitis

The distribution pattern you describe—wrists, ankles, and eyelid—is classic for allergic contact dermatitis (ACD), which accounts for 74% of eyelid dermatitis cases. 3 Your presentation strongly suggests exposure to a common allergen affecting multiple body sites.

Most Likely Culprits Based on Your Distribution:

• Nickel is the most common allergen in eyelid ACD (54% of cases) and frequently affects wrists from jewelry, watches, and electronic devices through hand-to-eye contact. 2
• Cobalt chloride (13.4% of eyelid ACD cases) often co-sensitizes with nickel and is found in jewelry and metal accessories. 2
• Fragrances and preservatives in cosmetics, soaps, and detergents can cause this distribution pattern, particularly affecting areas where products are applied or where skin contacts contaminated hands. 1, 4

Immediate Management Steps

Start with strict avoidance of suspected triggers and use topical hydrocortisone for symptomatic relief. 5

First-Line Treatment:

• Apply over-the-counter hydrocortisone cream to affected areas for temporary relief of itching and inflammation associated with eczema and contact dermatitis. 5
• Liberal emollient use multiple times daily to restore skin barrier function. 6
• Avoid potential triggers: Remove jewelry from wrists/ankles, switch to fragrance-free products, and minimize hand-to-face contact. 1, 4

Essential Diagnostic Workup

You need patch testing to definitively identify your allergen(s), as clinical features alone cannot distinguish between different causes of eczema. 1

Why Patch Testing is Critical:

• The British Association of Dermatologists emphasizes that clinical features are unreliable for distinguishing allergic from irritant or endogenous eczema, particularly with hand and eyelid involvement. 1
• Patch testing identifies the specific allergen in approximately 74% of eyelid dermatitis cases, enabling targeted avoidance strategies. 3
• Patients with eyelid dermatitis show single-hapten positivity in 54.6% of cases, making identification crucial for management. 2

Referral Threshold:

• Refer to dermatology for patch testing if symptoms persist beyond 2-4 weeks despite conservative management or if you have chronic/recurrent episodes. 1
• The recommended workload is approximately one patch test per 700 population annually, so access should be readily available. 1

Systemic Causes to Exclude

While contact dermatitis is most likely, the combination of dry scaly eyelid rash with generalized itching warrants limited systemic evaluation. 1, 6

Targeted Laboratory Testing:

• Complete blood count and ferritin level: Iron deficiency causes generalized pruritus in 25% of patients with systemic disease-related itch and responds rapidly to iron replacement. 1
• Thyroid function (TSH): Thyroid disease can cause both dry skin/pruritus and eyelid involvement. 1, 6
• Fasting glucose or HbA1c: Diabetes screening is part of standard pruritus evaluation. 6, 7

Important caveat: These tests are lower priority if your symptoms clearly follow allergen exposure patterns (e.g., worse after wearing jewelry or using specific products). 1

Eyelid-Specific Considerations

The eyelid requires special attention due to its unique anatomy and potential complications. 2, 3

Why the Eyelid is Particularly Vulnerable:

• Eyelid skin is 40 times more permeable than other body sites, making it highly susceptible to allergen penetration even from indirect contact (hand-to-eye transfer). 2, 4
• 88.6% of eyelid ACD patients are women, likely due to higher cosmetic use. 2
• Patients with eyelid ACD have higher rates of atopy (52.3%), which may complicate the clinical picture. 2

Red Flags Requiring Urgent Evaluation:

• Unilateral chronic eyelid dermatitis unresponsive to treatment may indicate sebaceous carcinoma masquerading as inflammation—this requires biopsy. 8
• Discharge from the medial canthus suggests concurrent conjunctivitis or nasolacrimal duct obstruction requiring separate evaluation. 9
• Vision changes, pain, or significant swelling warrant immediate ophthalmology referral to exclude orbital involvement. 8

Common Pitfalls to Avoid

• Don't assume the eyelid and extremity rashes are unrelated: The same allergen (especially nickel from jewelry/devices) can cause both through direct contact and hand-to-eye transfer. 2, 4
• Don't overlook atopic dermatitis: 16 of 23 atopic patients in one study also had concurrent ACD, so having atopy doesn't exclude contact allergy. 3
• Don't forget about nail products: Artificial nails and nail lacquer cause eyelid ACD through indirect transfer, though less commonly than previously thought (only 5 cases in one 203-patient series). 3, 4
• Don't use topical corticosteroids long-term without diagnosis: Corticosteroids themselves can cause ACD, and prolonged use on the eyelid can cause skin atrophy. 3, 4

Practical Algorithm for Your Situation

1. Immediately remove all jewelry from wrists and ankles; switch to fragrance-free, preservative-free products. 2, 4
2. Apply OTC hydrocortisone to affected areas twice daily for up to 2 weeks. 5
3. Use thick emollients (petrolatum-based) liberally and frequently. 6
4. If no improvement in 2 weeks or symptoms recur: Schedule dermatology consultation for patch testing. 1
5. If iron deficiency risk factors present (heavy menses, vegetarian diet, GI symptoms): Check CBC and ferritin now. 1

The key to successful management is identifying and strictly avoiding your specific allergen(s), which requires patch testing in most cases. 1, 3