What could cause lip swelling and redness in the axilla?

Differential Diagnosis and Management of Lip Swelling with Axillary Redness

The combination of lip swelling and axillary redness most likely represents either an infectious process (bacterial cellulitis/abscess or hand-foot-and-mouth disease) or an allergic/hypersensitivity reaction, and immediate evaluation for signs of systemic infection or anaphylaxis is critical.

Immediate Assessment Priorities

Rule Out Life-Threatening Conditions First

• Assess for anaphylaxis: Check for throat tightness, difficulty breathing, wheezing, weak pulse, dizziness, or widespread hives beyond the lip and axilla 1
• Evaluate for systemic infection: Measure temperature, assess for fever >100.4°F (>38°C), and look for signs of sepsis including tachycardia and altered mental status 1
• Examine for abscess formation: Palpate the lip for fluctuance, localized warmth, and purulent drainage which would indicate bacterial infection requiring drainage 2

Primary Diagnostic Considerations

1. Bacterial Infection (Staphylococcus aureus)

This is the most concerning diagnosis requiring urgent intervention, particularly if immunocompromised or if there are signs of abscess formation.

• Lip swelling from S. aureus (including MRSA) can present with acute inflammation, honey-colored crusting, pustular lesions, and induration 3, 4
• The axillary redness may represent lymphangitic spread or secondary cellulitis 2
• Immunocompromised patients (HIV, diabetes, other comorbidities) are at higher risk for severe infection 2
• Management approach: Obtain wound cultures before initiating antibiotics; if abscess is present, perform incision and drainage followed by IV antibiotics (vancomycin for suspected MRSA) transitioning to oral antibiotics based on culture sensitivities 2, 4
• Average inpatient stay for severe cases is 4 days with complete resolution expected with appropriate treatment 2

2. Hand, Foot, and Mouth Disease (HFMD)

Consider this diagnosis if there are vesicular lesions on hands/feet in addition to oral involvement, particularly in adults with recent exposure to children.

• HFMD can present with fever, oral lesions causing lip swelling, and widespread exanthema that may involve the axillary region 5
• Enterovirus 71 (EV-A71) is associated with more severe presentations 5
• Diagnostic confirmation: RT-PCR of vesicle fluid (highest viral load), respiratory samples, or stool specimens 5
• Management is supportive: Acetaminophen or NSAIDs for pain/fever; benzydamine hydrochloride oral rinse every 3 hours before eating; white soft paraffin ointment to lips every 2 hours 5, 6
• Monitor for neurological complications (encephalitis, meningitis, acute flaccid paralysis) particularly with severe cases 5

3. Allergic Contact Dermatitis/Hypersensitivity Reaction

Metal allergy or contact dermatitis can cause both lip swelling and axillary redness if there has been exposure to allergens in both locations.

• Metal hypersensitivity (particularly chromium, nickel) can cause persistent lip swelling and redness 7
• Axillary involvement suggests either systemic allergic reaction or contact with allergen in both areas 7
• Diagnostic approach: Detailed exposure history including dental work, jewelry, cosmetics, deodorants; consider patch testing if history suggests contact allergen 7
• Management: Remove offending agent; topical corticosteroids for inflammation; antihistamines for pruritus 7

4. Fungal Infection (Angular Cheilitis with Secondary Spread)

Less likely to cause isolated lip swelling without characteristic angular fissuring, but consider in immunocompromised patients.

• Candida infection typically presents with angular fissuring, but can cause diffuse lip inflammation 6, 8
• Treatment: Combination antifungal (nystatin 100,000 units QID or miconazole gel 5-10 mL QID) plus topical corticosteroid for inflammation 6
• For severe or resistant cases: fluconazole 100-200 mg daily for 7-14 days 6, 8
• White soft paraffin ointment every 2 hours for moisture and protection 6, 8

5. Vaccine-Related Reaction (If Recent Immunization)

Only relevant if patient received DTaP vaccine within past 3 days.

• Extensive limb swelling with associated redness can occur after DTaP vaccination, typically beginning within 3 days 1
• Axillary redness could represent injection site reaction if vaccine was administered in arm 1
• Median duration is 4 days (range 1-10 days) with self-limited course 1
• Management is supportive only: No specific intervention required; symptoms resolve spontaneously 1

Diagnostic Algorithm

Step 1: Emergency Evaluation (First 5 Minutes)

• Check vital signs and assess airway patency 1
• If anaphylaxis suspected: inject epinephrine 0.3 mg IM immediately 1
• If fever >100.4°F with systemic symptoms: obtain blood cultures and initiate broad-spectrum IV antibiotics 2

Step 2: Focused Physical Examination

• Lip examination: Look for fluctuance (abscess), honey-colored crusting (impetigo), vesicles (HFMD), angular fissuring (fungal), or diffuse edema without skin changes (angioedema) 2, 3, 5, 6
• Axillary examination: Assess for lymphadenopathy, injection site if recent vaccine, contact dermatitis pattern, or vesicular lesions 1, 5
• Oral cavity: Examine for ulcers, vesicles, or white plaques suggesting HFMD or candidiasis 5, 6
• Extremities: Check hands and feet for vesicles or rash suggesting HFMD 5

Step 3: Targeted History

• Timing: Onset within 3 days suggests vaccine reaction or acute infection; gradual onset over weeks suggests chronic process 1, 2
• Recent exposures: Sick contacts (HFMD), new dental work/jewelry (metal allergy), recent hospitalization (MRSA risk) 5, 7, 2
• Immune status: HIV, diabetes, immunosuppressive medications increase infection risk 2
• Associated symptoms: Fever and systemic symptoms suggest infection; pruritus suggests allergy 2, 7

Step 4: Laboratory and Imaging

• If infection suspected: CBC with differential, blood cultures if febrile, wound culture from lip lesion 2
• If HFMD suspected: RT-PCR of vesicle fluid or respiratory/stool specimens 5
• If abscess suspected: Ultrasound or CT to confirm abscess formation and extent 2
• If allergy suspected: Consider patch testing after acute phase resolves 7

Treatment Approach Based on Most Likely Diagnosis

For Bacterial Infection (Most Urgent)

1. If abscess present: Incision and drainage plus vancomycin 15-20 mg/kg IV every 8-12 hours pending cultures 2, 4
2. If cellulitis without abscess: Vancomycin IV if MRSA suspected, or cefazolin 1-2g IV every 8 hours if MSSA likely 2
3. Transition to oral antibiotics based on culture results after clinical improvement (typically 48-72 hours) 2
4. Expected duration: 4-day average hospital stay for severe cases with complete resolution 2

For HFMD (Supportive Care)

1. Pain management: Acetaminophen or NSAIDs for limited duration 5
2. Oral care: Benzydamine hydrochloride rinse every 3 hours, particularly before eating 5
3. Lip protection: White soft paraffin ointment every 2 hours 5
4. Hygiene: Handwashing with soap and water (more effective than alcohol sanitizers) 5
5. Isolation: Avoid close contact until fever resolves and mouth sores heal 5

For Allergic Reaction

1. Remove allergen: Discontinue suspected contact allergen immediately 7
2. Topical corticosteroids: Apply to affected areas twice daily 7
3. Oral antihistamines: For symptomatic relief of pruritus 7
4. Follow-up: Patch testing after resolution to identify specific allergen 7

Critical Pitfalls to Avoid

• Do not dismiss as simple angioedema without ruling out MRSA infection, which can mimic angioedema and requires urgent antibiotic therapy 4
• Do not delay surgical drainage if abscess is present; antibiotics alone are insufficient 2
• Do not use petroleum-based products chronically on lips as they promote mucosal dehydration and increase secondary infection risk 6
• Do not assume HFMD is only a pediatric disease; adults can develop severe manifestations requiring supportive care 5
• Do not overlook immunocompromised status, which dramatically increases risk of severe bacterial infection and may require more aggressive therapy 2, 6

When to Hospitalize

• Fever with systemic signs of infection 2
• Abscess requiring surgical drainage 2
• Immunocompromised patients with suspected bacterial infection 2
• Signs of airway compromise 1
• Inability to maintain oral hydration due to severe oral pain 5

Follow-Up Recommendations

• Bacterial infection: Reassess in 48-72 hours to confirm clinical improvement; complete full antibiotic course even if symptoms improve 2
• HFMD: Reassess after 2 weeks if lesions not improving; monitor for neurological complications 5
• Fungal infection: Evaluate response after 7-14 days; if no improvement, escalate to systemic therapy 6, 8
• Allergic reaction: Follow up after allergen removal to confirm resolution; arrange patch testing 7