Coexpression of ΔNp63/p40 and TTF1 Within Most of the Same Individual Cells Identifies Life-Threatening NSCLC Featuring Squamous and Glandular Biphenotypic Differentiation: Clinicopathologic Correlations

Non-small cell lung carcinoma with focal coexpression of thyroid transcription factor-1 and Δ Np63/p40: A case report

Most lung carcinomas are subtyped by their morphologies; however, immunohistochemistry is usually performed when it is difficult to determine. The most reliable antibodies for distinguishing lung adenocarcinoma from squamous cell carcinoma are thyroid transcription factor-1 (TTF-1) and p40 (ΔNp63). In general, these markers are mutually exclusive in their expression of lung primary carcinoma; however, a few cases of non-small cell lung carcinoma (NSCLC) with coexpression of both markers have been reported. Examining a tissue microarray of 229 squamous cell carcinomas and 346 adenocarcinomas, we found one case of NSCLC with coexpression of TTF-1 and p40. Herein, we present a 71-year-old man, who had a mass lesion in the left lung apex. A transbronchial lung biopsy was performed, revealing NSCLC. He underwent left upper segmentectomy and lymph node dissection. Macroscopically, the mass showed a white-to-tan solid tumor on the cut surface. Microscopically, the tumor was composed of polygonal tumor cells which had round and vesicular nuclei with prominent nucleoli. They had an abundant amount of cytoplasm, which was slightly eosinophilic or amphophilic. Multinucleated cells with atypical nuclear features were observed to be scattered in some areas. Multifocal necrosis and hemorrhage were also noted. Distinct squamous features and obvious glandular features were absent. Immunohistochemically, the most tumor cells were coexpressed positive for both TTF-1 and p40. In our study, NSCLC with TTF-1 and p40 coexpression is rare; therefore, it is necessary to obtain further data and examine similar cases to establish more precise definitions and clinicopathological features.

Clinicopathological Characteristics and Prognosis Analysis of Lung Carcinoma With p40/TTF1 Coexpression and Lung Adenosquamous Carcinoma: Lung Carcinoma With p40/TTF1 Coexpression Is a Rare Tumor With High Metastatic Potential

Background. Lung carcinoma with p40/TTF1 coexpression (LC-PTC) is a very rare tumor with poor prognosis, and few cases have been reported to date. Objectives. To better understand biological behavior and prognosis of LC-PTC. Methods. We collected 9 examples of LC-PTC and compared them with 36 lung adenosquamous carcinomas during the same period in clinicopathologic characteristics, biologic behaviour, and prognosis. Results. Lung carcinoma with p40/TTF1 coexpression mainly occurred in middle-aged and elderly men; 8 tumors belonged to the peripheral type, and 1 belonged to the central type. The rates of lymph node and distant metastasis were 88% (7/8) and 50% (4/8), respectively; 2 patients died during follow-up. Histologically, the LC-PTC showed nest-like growth pattern without glandular growth pattern; the surface of 2 tumors was covered with ciliated columnar epithelium and tumor cells grew under the columnar epithelium. In all patients, tumor cells diffusely coexpressed p40 and TTF1. Although there was no significant difference in the maximum diameter of tumor with lymph node metastasis or with distant metastasis between LC-PTC and lung adenosquamous carcinoma, LC-PTC had a higher rate of lymph node metastasis and distant metastasis. There was no significant difference in overall survival of patients between LC-PTC and lung adenosquamous carcinoma. Additional histologic evaluation of normal pulmonary structures revealed that p40/TTF1 coexpression cells existed in bronchial mucosa and the number of cells coexpressing p40/TTF1 increased gradually from proximal bronchus to distal bronchus. Conclusions. Lung carcinoma with p40/TTF1 coexpression is a rare tumor with high metastatic potential and may originate from p40/TTF1 coexpression cells in distal bronchial mucosa.

Biphenotypic lung carcinoma with coexpression of TTF-1 and ΔNP63/P40 within most of the same individual cells: a further case confirming poor prognosis and a review of literature

The WHO Classification of Tumors, Thoracic Tumors, 5th edition, has outlined the use of TTF-1 and ΔNP63/P40 to discriminate between adenocarcinoma and squamous cell carcinoma. In 2015, the first description of a rare non-small cell lung carcinoma featuring co-expression of glandular and squamous differentiation within most of the same individual tumor cells was reported on, with ultrastructural and molecular demonstration of such a biphenotypic differentiation. We herein describe an additional case of this rare tumor entity, which is confirmed to be an aggressive neoplasm despite potential targets of therapy.

TP53, NOTCH2, and STK11 Mutations in a Rare Tumor of non-Small Cell Lung Carcinoma with Diffuse Coexpression of TTF1 and p40 in the Same Tumor Cells

Introduction. Five cases of non-small cell lung carcinoma (NSCLC) with diffuse coexpression of TTF1 and p40 in the same tumor cells (hereafter referred to as TTF1/P40-NSCLC) have been reported since 2015. It was considered a new entity of NSCLC occurred in aged male smokers with poorly differentiated carcinomas and a similar molecular signature harboring a TP53 mutation. Methods. We report an extremely rare tumor of TTF1/P40-NSCLC. Morphological observation and immunohistochemical examination were performed, clinical and molecular features were summarized, and a review of the relevant literature was provided. Results. The tumor showed a solid growth pattern with patchy necrosis, and glandular and squamous pattern were not obvious. The tumor cells proliferated within the bronchial epithelium. Spreading through air spaces of tumor cells were observed. A peculiar immunohistochemical phenotype of diffuse and strong positivity for TTF1 (8G7G3/1) and p40 in the same tumor cells was detected. Additionally, the tumor cells were positive for KRT7 and KRT20, while negative for PD-L1 (22C3). Negative P53 (null) Immunohistochemistry (IHC) staining indicated mutational status and the Ki67 index was 80%. Molecular investigation was performed using whole exome sequencing, and TP53, NOTCH2, and STK11 mutations were detected. The patient remained alive over a follow-up period of 22 months without tumor recurrence or metastasis. Conclusions. We describe an unusual tumor of TTF1/P40-NSCLC harboring TP53, NOTCH2 and STK11 mutations. These gene mutations may be helpful in providing additional therapeutic possibilities. Our report offers further insight into this rare tumor.

Liver X receptors and estrogen receptor β, two players in a rare subtype of NSCLC

Liver X receptors (LXRαβ) play essential roles in the maintenance of the normal functions of macrophages, in modulation of immune system responses and cholesterol homeostasis. We have reported that LXRαβ^-/- mice develop squamous cell lung cancer. We now report that those LXRαβ^-/- mice, which live to 18-months of age, spontaneously develop a second type of lung cancer resembling a rare subtype of NSCLC (TTF-1 and P63-positive). The lesions are characterized as follows: a high proliferation rate; a marked accumulation of abnormal macrophages; an increase in the number of regulatory T cells; a remarkably low level of CD8⁺ cytotoxic T lymphocytes; enhanced TGFβ signaling; an increased expression of matrix metalloproteinases accompanied by degradation of lung collagen; and a loss of estrogen receptor β (ERβ). Because NSCLC is associated with cigarette smoking, we investigated the possible links between loss of LXRαβ and CS. A Kaplan-Meier Plotter database revealed reduced expression of LXRαβ and ERβ was correlated with low overall survival (OS). Thus, reduction of LXRαβ expression by cigarette smoking may be one mechanism through which CS causes lung cancer. The possibility that maintenance of LXRαβ and ERβ signaling could be used in the treatment of NSCLC needs further investigation.

Non-small cell lung carcinomas with diffuse coexpression of TTF1 and p40: clinicopathological and genomic features of 14 rare biphenotypic tumours

Thyroid transcription factor 1 (TTF1) and p40 are widely-utilized diagnostic markers of lung adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC), respectively. Diffuse coexpression of TTF1 and p40 has been described in only rare case reports. In a multi-institutional study, we collected the largest cohort of these unusual tumours to-date (n = 14), with the goal of elucidating their clinicopathological and genomic characteristics. Lung tumours with diffuse coexpression (labelling 50-100% tumour cells) of TTF1 clone 8G7G3/1 and p40 clone BC28 were identified. Detailed clinicopathological and immunohistochemical parameters were analyzed. Eight tumours were analyzed by next-generation sequencing (NGS) and the results were compared to those in > 9 K LUAD and > 1 K LUSC. All tumours with diffuse TTF1/p40 coexpression were poorly differentiated non-small cell lung carcinomas (NSCLC), 42% of which had basaloid features. Some tumours exhibited focal keratinization (14%), napsin A and/or mucicarmine labelling (46%) or both squamous and glandular features (7%). NGS revealed a uniquely high rate of FGFR1 amplifications (70%) compared to either LUAD (0.7%, P < 0.0001) or LUSC (11%, P = 0.001). LUAD-type targetable driver alterations were identified in 38% of cases (one EGFR, two KRAS G12C). The tumours were clinically aggressive, exhibiting metastatic disease in most patients. Lung carcinomas with diffuse TTF1/p40 coexpression represent poorly differentiated NSCLCs with frequent basaloid features, but some show evidence of focal squamous, glandular or dual differentiation with a distinctly high rate of FGFR1 amplifications. The presence of targetable LUAD-type alterations (EGFR, KRAS G12C) emphasizes the importance of molecular testing in these tumours.

P40 and TTF-1 double-expressing non-small cell lung cancer with EML4-ALK and PIK3CA gene mutations: A case report and review of the literature

P40 and thyroid transcription factor-1 (TTF-1) dual expression in non-small cell lung cancer (NSCLC) is a rare occurrence. However, the presence of EML4-ALK and PIK3CA gene mutations in this type of cancer is unknown. The present study describes the case of a 38-year-old male patient who had never smoked. A 4.5-cm mass adjacent to his right upper mediastinum was detected by a computed tomography (CT) scan of the chest. Biopsy of the level four lymph nodes in the right mediastinum revealed microscopic morphological features typical of high-grade NSCLC. Immunohistochemical findings resembled those reported previously for several cases of NSCLC with the dual expression of P40 and TTF-1 markers. In addition, echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit a (PIK3CA) gene mutations were detected using high-throughput next-generation sequencing. To the best of our knowledge, this is the first report of NSCLC with the expression of P40 and TTF-1 as well as EML4-ALK and PIK3CA gene mutations. The presence of this type of tumor should be considered in patients with NSCLC who have never smoked and may have unique clinicopathological features.