What is the diagnosis and treatment for a female patient with a rash along the bra line, severe pruritus, and swollen lymph nodes in the armpits?

Diagnosis and Management of Rash Along Bra Line with Severe Pruritus and Axillary Lymphadenopathy

This presentation most likely represents contact dermatitis or atopic eczema with secondary reactive lymphadenopathy, though inflammatory breast cancer must be urgently excluded in women over 45 years or with red flag features.

Immediate Diagnostic Priorities

Rule Out Malignancy First

Any woman presenting with a rash along the bra line accompanied by axillary lymphadenopathy requires immediate evaluation to exclude inflammatory breast carcinoma, particularly if:

• Age ≥45 years 1
• Symptoms present for less than 6 months with erythema occupying at least one-third of the breast 1, 2
• History of "mastitis" not responding to at least 1 week of antibiotics 1, 3
• Rapid onset with peau d'orange appearance, skin dimpling, or edema 1

If any red flags are present, obtain core needle biopsy or skin punch biopsy immediately to confirm or exclude malignancy before initiating treatment 1, 2. Ultrasound should be performed to evaluate the lymph nodes and distinguish solid from cystic masses 1.

Most Likely Benign Diagnosis

If malignancy is excluded or clinical suspicion is low (younger patient, chronic symptoms, typical eczematous appearance), this presentation most commonly represents:

Contact dermatitis from bra materials (elastic, dyes, nickel in clasps, detergent residue) or atopic eczema in the intertriginous area 4, 5. The severe pruritus and distribution along the bra line strongly suggest an allergic contact dermatitis 5.

The lymphadenopathy is likely reactive - enlarged lymph nodes commonly occur secondary to extensive inflammatory skin disease in otherwise healthy patients and should not cause alarm 4. However, lymphadenopathy associated with severe dermatitis can indicate superinfection or, rarely, underlying immunosuppression 6.

Diagnostic Workup for Benign Dermatitis

Clinical Assessment

• Examine for signs of secondary bacterial infection: crusting, weeping, honey-colored exudate, or pustules 4
• Check for contact dermatitis features: sharply demarcated erythema following the exact pattern of bra contact, vesicles, or lichenification 5
• Assess lymph nodes: size, tenderness, mobility, and whether bilateral or unilateral 4

Laboratory and Microbiological Studies

• If infection suspected: Obtain bacterial swabs for culture to identify Staphylococcus aureus or other pathogens 4
• If lymphadenopathy is prominent or persistent: Consider complete blood count, ESR, and lactate dehydrogenase to evaluate for underlying hematological conditions 4
• Skin biopsy is generally not helpful for typical eczema but may be necessary if diagnosis remains uncertain 4

Patch Testing

Patch testing is the gold standard for identifying allergenic contactants causing allergic contact dermatitis 5. This should be performed once acute inflammation subsides, testing for:

• Nickel (bra clasps)
• Rubber accelerators and elastic components
• Textile dyes
• Fragrance and preservatives in detergents 5

Treatment Algorithm

Step 1: Remove Contactant and Initiate Topical Therapy

Immediately advise the patient to:

• Stop wearing the suspected bra and switch to 100% cotton bras without elastic or metal components 5
• Wash all clothing in fragrance-free, dye-free detergent 5

Initiate topical corticosteroids:

• For trunk/intertriginous areas: Mid-potency topical corticosteroid (hydrocortisone 1-2.5% or equivalent) applied 2-3 times daily 4, 7
• Avoid high-potency steroids in intertriginous areas due to increased absorption and risk of skin atrophy 4
• Duration: Continue until inflammation resolves, typically 1-2 weeks 4

Liberal use of emollients is essential - prescribe adequate quantities and instruct patient to apply frequently throughout the day 4.

Step 2: Treat Secondary Infection if Present

If bacterial superinfection is evident (crusting, weeping, or positive cultures):

• First-line oral antibiotics: Cephalexin, dicloxacillin, or clindamycin for 7-10 days 4, 3
• If MRSA suspected or confirmed: TMP-SMX, doxycycline, or clindamycin 4, 3
• Cellulitis requires systemic antibiotics active against streptococci; 5-day course is as effective as 10 days if clinical improvement occurs 4

Step 3: Address Severe Pruritus

For intractable itching:

• Oral antihistamines (sedating at bedtime if sleep disruption occurs) 4
• Cool compresses to affected areas 4
• Avoid scratching - keep nails short and consider cotton gloves at night 4

Step 4: Monitor Lymphadenopathy

Reactive lymphadenopathy from extensive dermatitis should resolve as skin inflammation improves 4. However:

• If lymph nodes persist after dermatitis resolves, enlarge progressively, or are associated with systemic symptoms (fever, night sweats, weight loss), further investigation is mandatory 4
• Consider lymph node biopsy if nodes remain enlarged >4-6 weeks after skin disease resolution 4
• Pruritus with lymphadenopathy can rarely indicate lymphoma, particularly if accompanied by constitutional symptoms 4, 8

Common Pitfalls and Caveats

Do not dismiss axillary lymphadenopathy in women with breast area rashes - while usually reactive, inflammatory breast cancer can mimic dermatitis and must be excluded, especially in older women 1, 2.

Deterioration of previously stable eczema may indicate:

• Secondary bacterial infection requiring antibiotics 4
• Development of allergic contact dermatitis to topical treatments themselves 4
• Inadequate potency or quantity of topical corticosteroids 4

Avoid prolonged use of topical corticosteroids in intertriginous areas due to increased risk of skin atrophy, striae, and systemic absorption 4, 7.

If dermatitis persists despite appropriate treatment for 2-3 weeks, reconsider the diagnosis and evaluate for:

• Ongoing contactant exposure 5
• Cutaneous lymphoma (rare but can present with normal-appearing itchy skin) 4
• Underlying immunosuppression 6

Follow-Up

• Reassess in 1-2 weeks to evaluate treatment response 4
• If no improvement, consider referral to dermatology for patch testing and further evaluation 5
• Monitor lymph nodes - they should decrease in size as dermatitis improves 4
• Patient education is essential: provide written instructions on topical application techniques and quantities 4