The pathogenesis of pleuroparenchymal fibroelastosis (PPFE), a rare interstitial lung disease, remains unclear. Based on previous reports and our experience, we hypothesized that alveolar epithelial denudation (AED) was involved in the pathogenesis of PPFE. This multicenter retrospective study investigated the percentage of AED and the features of the denudated areas in 26 PPFE cases, 30 idiopathic pulmonary fibrosis (IPF) cases, and 29 controls. PPFE patients had lower forced vital capacities and higher residual volume/total lung capacities in pulmonary function tests compared to IPF and control patients. Histopathologically, subpleural fibroelastosis was observed in PPFE, and AED was observed in 12.01% of cases in the subpleural or interlobular septa regardless of fibroelastosis. The percentage of AED in the PPFE group was significantly higher than that in the IPF group (6.84%; p = 0.03) and the normal group (1.19%; p < 0.001). In the IPF group, the percentage of AED and the presence of PPFE-like lesions in the upper lobes were examined radiologically, but no correlation was found. We showed that AED frequently occurred in PPFE. AED was less frequent in IPF, which, in combination with imaging data, suggests that PPFE may have a different pathogenesis from IPF.

Purpose This study aimed to compare the clinicopathological features of stage I–II oral squamous cell carcinoma (OSCC) between adolescents and young adults (AYAs) and older patients, and to identify prognostic factors in AYA OSCC. Methods Forty-eight AYA patients aged 15–39 years and 69 older patients aged ≥ 65 years with surgically treated stage I–II OSCC were retrospectively analyzed. Histological evaluation, survival analysis, immunohistochemistry for p53, p16, and MTAP, high-risk HPV RNA in situ hybridization, and fluorescence in situ hybridization for CDKN2A and MTAP were performed. Results Compared with older patients, OSCCs in AYAs were more frequently located on the tongue (93.7% vs. 47.8%) and more often exhibited a superficial spreading growth pattern (60.4% vs. 31.8%). AYA tumors more frequently showed modified WPOI-1, high tumor budding, and abnormal p53 immunophenotypes (85.4% vs. 68.1%). AYA patients showed significantly better overall and disease-free survival than older patients. Within the AYA group, depth of invasion (DOI) > 5 mm was associated with distant metastasis and poorer overall and disease-free survival. Postoperative lymph node metastasis occurred in 31.2% of AYAs. Univariable analysis suggested that clinical stage II, tumor thickness > 5 mm, DOI > 5 mm, and tumor budding scores 1–2 were associated with postoperative lymph node metastasis. Molecular status, including p53, p16/CDKN2A, and MTAP, did not provide robust prognostic stratification. Conclusion Early-stage AYA OSCC exhibits distinct clinicopathological features. DOI was the strongest prognostic indicator, whereas clinical stage, tumor thickness, and tumor budding may provide additional prognostic information regarding the risk of late nodal metastasis.