Intermittent Blotchy Rash on Chest and Cheeks with Mild Swelling
The most likely diagnosis is a drug-induced papulopustular eruption (acneiform rash), particularly if the patient is on anticancer therapy such as EGFR or MEK inhibitors, and treatment should begin immediately with oral tetracyclines (doxycycline 100 mg twice daily OR minocycline 100 mg once daily) for at least 6 weeks, combined with topical low-to-moderate potency corticosteroids (hydrocortisone 2.5% or alclometasone 0.05%) applied twice daily to the face and chest. 1
Key Diagnostic Features to Assess
The intermittent nature and distribution (chest and cheeks) are critical diagnostic clues:
Medication history is paramount - specifically ask about EGFR inhibitors (erlotinib, afatinib, osimertinib, cetuximab), MEK inhibitors (trametinib, binimetinib, cobimetinib), or mTOR inhibitors, as these cause papulopustular eruptions in 75-90% of patients within days to weeks of initiation 1
Distribution pattern matters - papulopustular eruptions from anticancer agents characteristically appear on areas with high sebaceous gland density (face, chest, upper back), which matches this presentation 1
Associated symptoms - inquire about pruritus, stinging, pain, or burning sensations that typically accompany these eruptions 1
Timing - drug-induced rashes typically develop within the first days to weeks after medication initiation, though can occur up to 6 months later depending on pharmacokinetics 1
Immediate Management Algorithm
For Grade 1-2 Severity (covering <30% body surface area):
Continue the causative medication at current dose while monitoring for progression 1
Initiate oral tetracyclines immediately - doxycycline 100 mg twice daily OR minocycline 100 mg once daily for minimum 6 weeks due to antimicrobial and anti-inflammatory properties 1
Apply topical corticosteroids - low-to-moderate potency (hydrocortisone 2.5% or alclometasone 0.05%) twice daily to affected areas 1
Reassess after 2 weeks - if worsening or no improvement, escalate to next treatment tier 1
For Grade 3 Severity (covering >30% body surface area) or Intolerable Grade 2:
Interrupt the causative medication until rash returns to grade 0-1 1
Continue oral tetracyclines as above 1
Escalate topical corticosteroids to moderate-to-high potency 1
Add systemic corticosteroids - prednisone 0.5-1 mg/kg body weight for 7 days with weaning over 4-6 weeks 1
Essential Skin Care Measures
These supportive measures are critical regardless of severity:
Avoid frequent washing with hot water (hand washing, showers, baths) as this worsens barrier dysfunction 1
Avoid all skin irritants - over-the-counter anti-acne medications, solvents, disinfectants, harsh soaps 1
Apply alcohol-free moisturizers containing 5-10% urea at least twice daily to maintain skin barrier function 1
Use sun protection - SPF 15 or higher applied to exposed areas every 2 hours when outside 1
When to Suspect Bacterial Superinfection
Bacterial colonization or superinfection develops in up to 38% of drug-induced rashes and requires different management 1:
Obtain bacterial cultures BEFORE starting antibiotics if infection is suspected 1
Signs of superinfection include: failure to respond to oral tetracyclines covering gram-positive organisms, presence of painful skin lesions, pustules extending to arms/legs/trunk, yellow crusts, purulent discharge 1
Treat with culture-directed antibiotics for at least 14 days based on sensitivities 1
Alternative Diagnoses to Consider
If rash is unilateral and dermatomal:
Herpes zoster should be the primary consideration if pustular lesions follow a strict unilateral distribution respecting the midline 2
Initiate oral acyclovir immediately without waiting for laboratory confirmation if started within 72 hours of rash onset 2
If patient has systemic symptoms:
DRESS syndrome (Drug Reaction with Eosinophilia and Systemic Symptoms) or Stevens-Johnson syndrome must be excluded if there are vesicles, skin detachment, mucous involvement, or systemic symptoms 1
Discontinue ALL medications immediately and hospitalize urgently if DRESS or SJS suspected 1
Critical Pitfalls to Avoid
Do not use prophylactic corticosteroids or antihistamines to prevent drug-induced rashes, as this has not shown benefit and may increase risk 1
Do not delay treatment while awaiting definitive diagnosis - clinical diagnosis is sufficient to initiate therapy 2
Do not use vitamin K1 cream - randomized studies show no benefit in preventing or treating drug-induced rashes 1
Do not combine isotretinoin with tetracyclines due to risk of cerebral edema 1