A 65-year-old Chinese woman was referred to the ophthalmology clinic complaining of grittiness in both eyes for 1 month. She had been diagnosed with stage IV metastatic pulmonary adenocarcinoma with positive mutation in epidermal growth factor receptor (EGFR) gene (L858R) and had been prescribed erlotinib 4 months previously as palliative treatment (Table).

Physical examination revealed bilateral long thick curly eyelashes (Figs 1 and 2) affecting all four eyelids. A papulopustular rash over the periocular region was also evident. The patient denied use of topical prostaglandin analogue for either medical or cosmetic use. A diagnosis was made of drug-induced trichomegaly. Corneal punctate epithelial erosion as a result of the misdirected lashes was treated symptomatically with regular epilation and topical lubricants.

Upon follow-up, gradual partial reversal of trichomegaly was evident at 6 weeks after erlotinib cessation. There was also improvement of the periorbital papulopustular rash. The reversal of trichomegaly after EGFR inhibitor cessation is not well documented in the literature. This case illustrates the presentation and partial resolution of drug-induced trichomegaly.

Eyelash trichomegaly is a rare condition characterised by increase in length, thickness, pigmentation, and curling of the eyelashes. The eyelash follicle, just as the scalp hair follicle, undergoes the cycle of anagen, catagen, and telogen phase. The anagen phase of eyelashes (ie, the growth phase) typically spans 8 weeks in Asian patients and occurs in 18% of eyelashes at any given time.1

Drug-induced trichomegaly is the most common form of trichomegaly to present in a general ophthalmology setting. Prostaglandin analogues such as latanoprost and bimatoprost, although commonly used as antiglaucomatous drugs, are well known for their side-effect of eyelash trichomegaly. The effect is due to up-regulation of prostaglandin E2, D2 receptor expressed in hair follicles.2

The occurrence of EGFR inhibitor–induced trichomegaly is seen less often but is not uncommon in the ophthalmology setting. It has been postulated that EGFR inhibitors inactivate the nuclear factor of activated T-cells. This leads to activation of stem cell bulge and suprabulbar region of the eyelash hair follicles.3 In a typical course, trichomegaly develops between the second and fifth month of EGFR inhibitor treatment.4 An Asian study reported that 2% of patients prescribed EGFR inhibitor treatment had trichomegaly.5 The EGFR inhibitor is also well known to cause a series of cutaneous adverse effects known as the PRIDE syndrome (papulopustules and/or paronychia, regulatory abnormalities of hair growth, itching, and dryness).6 In this case, the patient exhibited PRIDE syndrome affecting the periocular skin as demonstrated in Figures 1 and 2.

Trichomegaly is a benign condition, but long misdirected lashes may lead to corneal punctate epithelial erosion and corneal abrasion. Frequent trimming, epilation, and topical lubricants serve as first-line treatment. Electro-epilation or cryoablation directed at the affected hair follicles may be considered in instances of recurrent misdirected lashes with corneal complications such as infective corneal ulcer.

This case highlights the clinical course of EGFR inhibitor–induced trichomegaly upon cessation of drug therapy, which is not well documented in the literature. Partial reversal of trichomegaly was achieved after stopping erlotinib for 6 weeks. It is evident that the time required for trichomegaly resolution follows the typical eyelash follicle cycle.

All authors contributed to the design, acquisition of data, analysis of data, drafting of the manuscript, and critical revision of the manuscript for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

As an adviser of the journal, HKL Yuen was not involved in the peer review process. Other authors have disclosed no conflicts of interest.

This pictorial medicine received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

The patient was treated in accordance with the Declaration of Helsinki. The patient provided written informed consent for the treatment/procedures, and consent for publication.

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