[Erlotinib-induced scarring alopecia with a folliculitis decalvans-like presentation]

Epidermal growth factor receptor (EGFR) inhibitors are targeted therapies that frequently induce skin eruptions such as acneiform rash. Due to their increasing use in oncology as well as the expanding number of exposed patients, new adverse events may emerge.

A 54-year-old female patient treated with erlotinib for 8 months for pulmonary adenocarcinoma presented inflammatory alopecia that had been ongoing for 1 month. Her condition did not improve with doxycycline 100mg/day. Diffuse erythema of the scalp was associated with painful keratotic plaques and several oozing lesions. A skin biopsy showed signs of acute suppurative and destructive folliculitis. Histology and dermatoscopy were consistent with a diagnosis of folliculitis decalvans. Marked improvement was observed after discontinuation of erlotinib followed by introduction of amoxicillin+clavulanic acid and application of a topical corticosteroid. Unfortunately, the lesions recurred after reintroduction of the anti-EGFR, despite a dosage reduction, requiring up-titration of doxycycline to 200mg/day.

Scarring alopecia with a folliculitis decalvans-like presentation secondary to anti-EGFR is a rare adverse event. The exact pathophysiology remains poorly understood. Treatment is difficult, and while systemic antibiotics are effective, they must be maintained for a long duration in order to avoid recurrence. Early recognition is important to limit the development of scarring alopecia due to the difficulties of stopping treatment in advanced-stage carcinoma.