Clinical trials have shown the superiorityof a combined anti-HER2 regimen for both local and advanced breast cancer when comparedwith alternative therapies.7-11 In this case, we present, to the bestof our knowledge, the first reported case of accidental intrapleural administration ofpertuzumab, trastuzumab, and docetaxel (PTH). The gene discussed is ERBB2; the disease is breast cancer.