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

TTF-1 and p40 co-expressing non-small cell lung cancer with ERBB2 and TP53 gene mutations: A case report and review of the literature

RATIONALE

Non-small cell lung cancer (NSCLC) that co-expresses thyroid transcription factor-1 (TTF-1) and p40 represents a distinct subtype of lung cancer. This case report details a 53-year-old male patient with NSCLC exhibiting co-expression of TTF-1 and p40, highlighting the need for further investigation into this unique presentation of NSCLC.

PATIENT CONCERNS

A 53-year-old male, nonsmoker, presented to our hospital in November 2023 with complaints of cough, expectoration, chest pain, and dyspnea.

DIAGNOSES

Computed tomography scans revealed perihilar lesions in the upper lobe of the right lung with distal obstructive pneumonia, invasion into adjacent mediastinal structures, multiple pulmonary metastases, possible mediastinal and right hilar lymph node metastases, pleural effusion, and a slightly thickened pleura in the right lung, along with multiple metastatic lesions in the liver. Immunohistochemical analysis showed positive staining for CK (AE1/AE3), TTF-1, and p40, while CK56, CD68, CD45 (LCA), D2-40, and Ki-67 (50%+) were negative, leading to the diagnosis of lung adenocarcinoma. Second-generation sequencing identified mutations in ERBB2 (EXON20.p.Y772-A775dup) and TP53 (EXON5.c.404G-Tp.C135F).

INTERVENTIONS

The patient underwent 6 cycles of chemotherapy with a regimen consisting of bevacizumab, pemetrexed, and carboplatin.

OUTCOMES

Posttreatment evaluations on December 28, 2023, and February 25, 2024, indicated stable disease. The patient is currently on a maintenance chemotherapy regimen of bevacizumab and pemetrexed, and his condition is stable.

LESSONS

The co-expression of TTF-1 and p40 in NSCLC may define a novel subtype of lung cancer. Further research is imperative to elucidate its characteristics, molecular mechanisms, and to establish its morphological features and therapeutic strategies.

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.

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.