EGFR-inhibitor papulopustular eruption

Acneiform eruption; EGFRI rash; cetuximab rash; erlotinib rash; papulopustular drug rash

The EGFR-inhibitor papulopustular eruption is the most characteristic skin toxicity of epidermal-growth-factor-receptor inhibitors — monoclonal antibodies (cetuximab, panitumumab) and small-molecule tyrosine kinase inhibitors (erlotinib, gefitinib, afatinib, osimertinib). It affects 60–90% of patients within the first 1–3 weeks, in a seborrhoeic distribution on the face, scalp, upper chest and back, with sterile inflammatory papules and pustules and occasional crusting. Importantly, rash severity correlates with treatment response — patients with the highest-grade eruption have the best tumour outcomes. Prophylactic doxycycline ± topical corticosteroid significantly reduces severity in randomised trials (STEPP). It is distinct from acne despite the acneiform appearance.

CurrentLast reviewed 15 May 2026

Clinical features

Sterile inflammatory papules and pustules in a seborrhoeic distribution — face (cheeks, nose, forehead), scalp, upper chest, upper back.
Onset typically 1–3 weeks after starting therapy; peaks at 3–5 weeks; settles to a less inflamed papular state with continued treatment.
Pruritus and burning common; sometimes crusting and pain.
Distinct from acne — no comedones, less follicular orientation, lacks androgen-dependent pattern.
Other EGFRI cutaneous toxicities — paronychia, fissures of digits, hair changes (curling, thinning, eyelash trichomegaly), xerosis.

Biology and response correlation

EGFR signalling is essential for keratinocyte proliferation and survival; inhibition leads to keratinocyte apoptosis, follicular obstruction and inflammatory infiltrate.
Rash severity is the strongest clinical predictor of treatment response — patients with G2–G3 rash have significantly higher response rates and longer survival.
This biology-driven correlation makes severity a "good news" sign provided it is managed proactively rather than driving dose reduction.

Grading (CTCAE)

Grade 1 — papulopustular eruption on < 10% BSA, with or without symptoms; no impact on ADLs.
Grade 2 — 10–30% BSA, psychosocial impact; oral antibiotic and topical therapy.
Grade 3 — > 30% BSA, severe symptoms, limiting self-care, superinfection; hold drug, dermatology referral, systemic steroid in selected cases.
Grade 4 — life-threatening superinfection or extensive desquamation; rare; admit; permanent drug discontinuation considered.

Management

Prophylactic (STEPP regimen) — doxycycline 100 mg twice daily PLUS topical hydrocortisone 1% PLUS emollients PLUS broad-spectrum sunscreen from day 1 of therapy. Reduces incidence and severity by ~ 50%.
Established Grade 1 — emollient + topical clindamycin or metronidazole; sunscreen.
Grade 2 — doxycycline 100 mg BD (or minocycline 100 mg BD); topical mid-potency steroid; systemic corticosteroids are rarely needed and reserved for severe or refractory disease after dermatology input.
Grade 3 — doxycycline + topical / oral steroid; consider dose interruption ± reduction; dermatology input; bacterial swab if superinfection suspected.
Counsel patients — the rash is expected, predicts response, and is managed not dose-reduced unless severe.
Sun avoidance and photoprotection — the rash worsens with UV.

Differential

Acne vulgaris — comedones present; preceding history.
Rosacea — different distribution, flushing, ocular involvement.
Folliculitis — bacterial culture positive.
Steroid-induced acne — preceding steroid exposure.

References

Lacouture ME et al. Skin toxicity evaluation protocol with panitumumab (STEPP) — prophylactic vs reactive skin treatment. J Clin Oncol; 2010.

Sibaud V et al. Pre-emptive management of EGFR-inhibitor-induced rash. Support Care Cancer; 2016.

National Comprehensive Cancer Network. Management of immunotherapy-related toxicities / oncology supportive-care guidance relevant to EGFR-inhibitor dermatologic toxicity. Accessed 18 May 2026.