Application of the WHO Classification of Thoracic Tumors (2021) grading system in invasive pulmonary adenocarcinoma and its correlation with the targeted genes' variations / 中华病理学杂志

Objective: To investigate the applicability of the 2021 WHO classification of thoracic tumors' new grading system for invasive pulmonary adenocarcinoma (IPA) with different clinical stages and its correlation with the characteristics of targeted genes' variation. Methods: A total of 2 467 patients with surgically resected primary IPA in Shanghai Pulmonary Hospital, Shanghai, China from September to December 2020 were retrospectively analyzed. Eligible cases were graded using the new grading system of IPA of the 2021 WHO classification of thoracic tumors. The clinicopathological data and targeted-gene abnormality were collected. The utility of new grading system of IPA in different clinical stages was investigated. The correlation of clinicopathological features and targeted-gene abnormality in different grades of IPA were compared. Results: All 2 311 cases of IPA were included. There were 2 046 cases of stage Ⅰ IPA (88.5%), 169 cases of stage Ⅱ (7.3%), and 96 cases of stage Ⅲ (4.2%). According to the new classification system of IPA, 186 cases (9.1%), 1 413 cases (69.1%) and 447 cases (21.8%) of stage-Ⅰ adenocarcinoma were classified as Grade 1, Grade 2 and Grade 3, respectively. However, there were no Grade 1 adenocarcinomas in stages Ⅱ and Ⅲ cases. Among stage-Ⅱ and Ⅲ IPA cases, there were 38 Grade 2 cases (22.5%) and 131 Grade 3 cases (77.5%), and 3 Grade 2 cases (3.1%) and 93 Grade 3 cases (96.9%), respectively. In stage-Ⅰ cases, no tumor cells spreading through airspace (STAS), vascular invasion or pleural invasion was found in Grade 1 of IPA, while the positive rates of STAS in Grade 2 and 3 IPA cases were 11.3% (159/1 413) and 73.2% (327/447), respectively. There was a significant difference among the three grades (P<0.01). Similarly, the rates of vascular and pleural invasion in Grade 3 IPA cases were 21.3% (95/447) and 75.8% (339/447), respectively, which were significantly higher than those of 1.3% (19/1 413) and 3.0% (42/1 413) in Grade 2 (P<0.01). EGFR mutational rates in Grades 1, 2 and 3 IPA were 65.7% (94/143), 76.4% (984/1 288) and 51.3% (216/421), respectively. The differences among the three grades were statistically significant (P<0.01). No fusion genes were detected in Grade 1 IPA, while the positive rates of ROS1 and ALK fusion genes in Grade 3 were 2.4% (10/421) and 8.3% (35/421), respectively, which were significantly higher than that of 0.5% (7/1 288) and 1.6% (20/1 288) in Grade 2 (P<0.01). In stage-Ⅱ cases, only EGFR mutation rate in Grade 2 adenocarcinoma (31/37, 83.8%) was higher than that in Grade 3 adenocarcinoma (71/123, 57.7%; P<0.01). However, the correlation between the new grade system of IPA and the distribution characteristics of targeted-gene variation cannot be evaluated in stage Ⅲ cases. Conclusions: The new grading system for IPA is mainly applicable to clinical stage-Ⅰ patients. Tumor grades of IPA are strongly correlated with the high-risk factors of prognosis and the distribution features of therapeutic targets. It is of great significance and clinical value to manage postoperative patients with early-stage IPA.

Primary lung salivary gland-type duct carcinoma: a clinicopathological analysis of two cases and review of literature / 中华病理学杂志

Objective: To investigate the clinicopathological features, diagnostic criteria and differential diagnosis of primary salivary gland-type duct carcinoma of lung(LSDC). Methods: Two patients with LSDC after surgical resection in Shanghai Pulmonary Hospital from 2020 to 2021 were included; their clinical parameters as well as pathological, immunohistochemical and molecular characteristics of the tumors were analyzed. The relevant literature was also reviewed. Results: Both patients were male, aged 49(case 1) and 64(case 2) years, respectively, and with a history of smoking. The chest computed tomography scan showed both lesions to be centrally located. Gross examination showed the maximum diameters were 16 mm and 35 mm, respectively. The histomorphology of LSDC resembled ductal carcinoma of breast, with intraductal islands of neoplastic cells, which also formed solid nests, papillary, micropapillary and cribriform structures. There was frequent accompanying comedo-like necrosis. The neoplasm cells were markedly heteromorphic, possessing large irregular nuclei with prominent nucleoli, abundant eosinophilic or clear cytoplasm, and mitotic figures were common. Both cases of LSDC were immunoreactive for CKpan, CK7, AR, HER2 staining was (2+) and were negative for TTF1, Napsin A, p40, GATA3, mammaglobin, GCDFP15, SOX10, PSA, P504S, ER, PR, vimentin, S-100, SMA, CK5/6 and p63. The tumor showed double-layer cell structure of the duct, and some basal cells/myoepithelial cells expressed p40 and CK5/6. Case 1 had no gene mutation while case 2 harbored TP53 and KMT2A gene mutation detected by next generation sequencing. Conclusions: LSDC is a very rare and highly aggressive salivary-type malignant tumor. The postoperative diagnosis mainly depends on histopathology and immunohistochemistry, attention should be paid to differential diagnosis to prevent missed diagnosis.

Clinicopathological and genetic characteristics of bronchial sialadenoma papilliferum: report of four cases / 中华病理学杂志

Objective: To investigate the clinicopathological, immunophenotypic, and molecular genetic features of bronchial sialadenoma papilliferum (BSP). Methods: Four cases of BSP collected at the Shanghai Pulmonary Hospital from May 2018 to June 2021 were retrieved and analyzed. These cases were evaluated for their clinical, histological, immunohistochemical (IHC) and genomic features. The patients were followed up and relevant literature was reviewed. Results: All four patients were male, aged from 55 to 75 years (mean 62 years), with tumor diameter of 6 to 21 mm (mean 13.5 mm), and lesions were located in the left lower lobe (n=2), right lower lobe (n=1), and trachea (n=1). They were characterized by a combination of surface exophytic endobronchial papillary proliferation and an endophytic two-cell layered ductal structure. IHC staining showed that CK7 and EMA were strongly positive in ductal epithelium; p63, p40, CK5/6 were positive in ductal and papillary basal cells; SOX10 was positive in ductal epithelium and basal cells; S-100 was positive in basal cells and ductal epithelium in two cases. Next generation sequencing showed that two cases harbored BRAF V600E mutation. Conclusions: BSP is an extremely rare primary lung tumor arising from the salivary gland under bronchial mucosa. The primary treatment choice of this tumor is complete surgical resection. The diagnosis and differential diagnosis of this tumor depend on classic histomorphologic and IHC features, and BRAF V600E gene mutation can be detected.