Is the interstitial lung disease induced by trastuzumab? Case report and literature review.

WHAT IS KNOWN AND OBJECTIVE: Interstitial lung disease (ILD) is a rare but life-threatening adverse event (AE) that can be induced by trastuzumab in patients with breast cancer. ILD is a known AE associated with trastuzumab therapy, but it has other causes. We describe a case of ILD, which was induced by Epstein-Barr virus (EBV). CASE SUMMARY: A 76-year-old female patient with early-stage HER-2-positive breast cancer presented with ILD after 10 cycles of trastuzumab and paclitaxel. After excluding the possibility of trastuzumab-induced AE, Epstein-Barr virus (EBV) was thought to be a possible cause. Her symptoms resolved after ganciclovir therapy and did not recur following reintroduction of trastuzumab therapy. WHAT IS NEW AND CONCLUSION: Given the known association of ILD with trastuzumab therapy, it was tempting to assign causality to this drug. Our investigations and observed treatment response of our patient to ganciclovir suggest that EBV was the cause.