A 90-year-old female was admitted to our hospital with a history of a dry cough. Chest computed tomography (CT) scan showed a tumor shadow, and CT-guided lung biopsy revealed squamous cell carcinoma harboring an EGFR mutation. In addition, programmed death-ligand 1 (PD-L1) was highly expressed with a tumor proportion score (TPS) of >75%. Pembrolizumab therapy in the first-line setting was not effective, and the patient died at six months from the first visit. Squamous cell lung cancers (SCLCs) with both EGFR mutation and high expression of PD-L1 are very rare.

This is the first report describing primary pulmonary mucosa-associated lymphoid tissue (MALT) lymphoma with the high expression of IgG4. The histological findings were compatible with the diagnostic criteria for MALT lymphoma and IgG4-related respiratory disease (IgG4-RRD). An unfixed sample for Southern blotting was not obtained since computed tomography findings showed multiple lung cysts, which is rare in patients with MALT lymphoma. However, polymerase chain reaction using paraffin sections showed the clonality of the immunoglobulin heavy chain variable region gene rearrangement, confirming a diagnosis of MALT lymphoma. This is an instructive case in which primary pulmonary MALT lymphoma was histologically compatible with IgG4-RRD.

Background and Objective Checkpoint inhibitor pneumonitis (CIP), caused by the anti‐programmed cell death‐1 (PD‐1)/programmed cell death ligand‐1 (PD‐L1) antibody, can be a fatal adverse event in cancer patients. However, no predictive biomarkers for CIP have been identified. Because high‐mobility group box 1 (HMGB1) can aggravate lung injury and potentially increase the immune response, it was investigated as a predictive blood marker. Methods Blood samples, prospectively stored before anti‐PD‐1/PD‐L1 monotherapy between December 2015 and October 2020, were obtained at two university hospitals from 87 and 43 non‐small cell lung cancer (NSCLC) patients (discovery and validation cohorts, respectively). We retrospectively evaluated the association of serum HMGB1 levels with the incidence of CIP developed within 3 months of initiating anti‐PD‐1/PD‐L1 therapy. Results CIP was observed in 9 (10.3%) and 6 (14.0%) patients in the discovery and validation cohorts, respectively. In each cohort, serum HMGB1 levels were significantly and reproducibly higher in patients with CIP. In the discovery cohort, an HMGB1 cut‐off level of 11.24 ng/ml was identified by receiver operating characteristic analysis. CIP incidence in the HMGB1high subgroup was significantly higher than that in the HMGB1low subgroup in the discovery (41.2% vs. 2.9%) and validation cohorts (36.4% vs. 6.3%). In an exploratory pooled analysis, three patients died of grade 5 CIP; a 19.29 ng/ml HMGB1 cut‐off level detected grade 5 CIP with 100% sensitivity and 96.85% specificity. Conclusion Our results suggest that HMGB1 may be a potential blood marker to predict the development and severity of CIP in NSCLC patients.

No abstract