Primary pulmonary mucinous adenocarcinoma is a rare subtype of lung adenocarcinoma. It differs from non-mucinous adenocarcinoma in etiology, pathogenesis, clinical, imaging, histological, immunophenotypic and genotypic features, prognosis and treatment. pulmonary mucinous adenocarcinoma mainly originates from bronchial basal cells and mucous cells. Tumor cells show a goblet and/or columnar cell morphology with abundant intracytoplasmic mucin and basally oriented nuclei, with a typical lepidic-predominant growth, the commonest molecular alterations are KRAS mutations.

Esophageal cancer is one of the common diseases that threaten human health, with high morbidity and mortality. The main histological types are squamous cell carcinoma and adenocarcinoma, both of which have unique pathophysiological changes, major risk factors, epidemiological characteristics and morphological changes. Most patients are locally advanced at the first visit, and neoadjuvant combined surgery has become the standard treatment for these patients. After neoadjuvant therapy, residual tumor cells in surgical resection specimens are related to prognosis. Pathologists need to understand the histopathological changes of esophageal cancer after neoadjuvant therapy and conduct a comprehensive and standardized evaluation of the degree of tumor regression to provide valuable prognostic information and guide further treatment.

Objective:To investigate the clinicopathological characteristics and possible pathogenesis of immune checkpoint inhibitor (ICI) induced myocarditis, and to improve understanding of this new type of myocarditis.Methods:Two cases of ICI induced myocarditis with endomyocardial biopsy available for review were selected from the cases with immune-related adverse events treated by ICI in Peking University First Hospital, Beijing, China from 2020 to 2022. The clinical data, histomorphological characteristics, PD-L1 expression of cardiomyocytes, and classification of inflammatory cells in two cases of ICI-induced myocarditis were analyzed. Relevant literature was reviewed.Results:Case 1 was a 64-year-old male diagnosed with gastric signet ring cell carcinoma. Case 2 was a 56-year-old male ad diagnosed with lung squamous cell carcinoma. Both patients developed acute myocarditis during PD-1 inhibitor treatment, and the disease progressed rapidly. Case 2 was more serious than case 1. Endomyocardial biopsy showed definite cardiomyocytic injury and prominent inflammatory infiltration in both cases, which met the full Dallas criteria for myocarditis. The degenerated and necrotic cardiomyocytes accounted for about 10% of the tissues in case 1 and 30% in case 2, respectively. In case 1, the inflammatory cells counted in the densest area were about 150/HPF, comprised of CD20 + cells (about 5/HPF), CD3 + cells (about 60/HPF), CD8 + cells (about 50/HPF) and CD68 + cells (about 70/HPF). In case 2, the inflammatory cells counted in the densest area were about 350/HPF, comprised of CD20 + cells (0/HPF), CD3 + cells (about 100/HPF), CD8 + cells (about 90/HPF) and CD68 + cells (about 200/HPF). In both cases, PD-L1 + cardiomyocytes aggregated in the inflammatory lesions, and the percentage was about 8% and 30% in case 1 and case 2, respectively. Conclusions:ICI-induced myocarditis is frequently acute onset, severe symptoms, and rapid progression. The histological morphology meets the full Dallas criteria for myocarditis. Expression of PD-L1 in cardiomyocytes can be detected in the inflammatory lesions. The inflammatory cells are comprised of CD8 + T lymphocytes and macrophages and the number of macrophages significantly exceeds that of lymphocytes. Combined with the pathological characteristics and the history of ICI treatment, the diagnosis of ICI-induced myocarditis can be made.

Objective: To study the clinicopathological characteristics of lung salivary gland-type tumors (SGT), and to compare with the corresponding primary SGT in salivary glands. Methods: Twenty-three cases of lung SGT were retrieved from the files of Peking University First Hospital from January 2004 to September 2018. The morphology, immunophenotype, genotype and outcome of these cases were analyzed. Results: The 23 patients included 13 males and 10 females, with age range of 13-79 years (median 54 years). There were 11 cases of adenoid cystic carcinoma, 10 cases of mucoepidermoid carcinoma (MEC), one case each of clear cell carcinoma and myoepithelioma. The morphology and immunophenotype of lung SGT were very similar to their counterparts in salivary gland. MYB rearrangement was detected in one of 11 adenoid cystic carcinomas. MAML2 rearrangement was detected in all the MECs. EWSR1 rearrangement was detected in the one case of clear cell carcinoma. Of patients with adenoid cystic carcinoma, the survival time was more than 60 months (three cases), 52 months (one case), and 12-36 months (three cases). There was no recurrence and death in seven cases of MEC with follow-up results. One case of clear cell carcinoma recurred after 52 months of follow-up. Conclusions Although the SGT of lung and their counterparts in salivary gland are very similar in their morphology, immunophenotype, genotype and prognosis, there are also some differences between each other. MYB rearrangement can be detected in most adenoid cystic carcinomas of salivary gland, but rarely in lung adenoid cystic carcinoma. The prognosis of patients with lung MEC is better than that of patients with salivary gland MEC, while the prognosis of patients with lung adenoid cystic carcinoma is worse than that of patients with salivary gland adenoid cystic carcinoma.