Analysis of blood neutrophil elastase, glutathione levels and pathological findings in postoperative acute exacerbation of idiopathic pulmonary fibrosis associated with lung cancer: Two case reports.

Acute exacerbation (AE) of idiopathic pulmonary fibrosis (IPF) is characterized by severe worsening dyspnea and high mortality. It has been proven that the serum neutrophil elastase (NE) level, in addition to the serum Krebs von den Lungen-6 (KL-6) and surfactant protein-D (SP-D) levels, was elevated in patients with IPF-AE. Glutathione (GSH) is the major antioxidant involved in cell metabolism and survival. It is also known that IPF is characterized by reduced GSH levels in bronchoalveolar lavage fluid and blood. Case 1 was a 67-year-old man who was referred to our hospital complaining of a 2-year history of progressive dyspnea on exertion (DOE). The patient was initially diagnosed with IPF, followed by inhaled N-acetylcysteine monotherapy. Two years later, left upper lobectomy with lymph node dissection was performed due to primary lung cancer, which was large-cell neuroendocrine carcinoma (pT2aN2M0, stage IIIA). Five days after lung surgery, the patient developed AE. Case 2 was a 67-year-old man who was referred to our hospital with suspected lung cancer, complaining of dry cough and DOE. The patient underwent left upper lobectomy with lymph node dissection for primary lung cancer, which was diagnosed as well-differentiated adenocarcinoma (pT2aN2M0, stage IIIA). Ten days after lung surgery, the patient developed AE. The levels of biomarkers, such as serum NE, redox balance [reduced GSH (rGSH)/oxidized GSH (GSSG)] in the blood, as well as the correlation between serial changes of these biomarkers and prognosis, were analyzed in 2 patients with postoperative IPF-AE associated with lung cancer. Interestingly, the serial changes of the serum rGSH/GSSG ratio may suggest the possibility of predicting the onset of postoperative AE and/or survival, along with serum NE levels.