Reversible Restrictive Lung Disease in Pseudomesotheliomatous Carcinoma in a Lung Harboring a HER2-mutation

Pseudomesotheliomatous carcinoma of the lung is very rare, and reversible restrictive lung disease with pseudomesotheliomatous carcinoma has not yet been previously reported. We herein report a patient with HER2-positive non-small-cell lung cancer (NSCLC) showing pseudomesotheliomatous carcinoma who was successfully treated with bevacizumab combination chemotherapy. A 56-year-old Japanese woman with advanced NSCLC presented with dyspnea. We administered chemotherapy with cisplatin (75 mg/m²) plus pemetrexed (500 mg/m²) plus bevacizumab (15 mg/kg), followed by pemetrexed plus bevacizumab. After eight cycles of maintenance chemotherapy, chest CT demonstrated a marked tumor reduction and an improvement of the right lung volume. The vital capacity was thereafter found to have significantly increased according to pulmonary function tests.