Non-Small Cell Lung Carcinoma With Bilayered Architecture and TP53 Alteration: A Diagnostic Pitfall and a Potential Distinct Entity.
Yao Liu, Biao Zhang, Xiaobin Cui et al.
✦ AI-curated · Sources linked
Case in brief
A 75-year-old never-smoker had a 1.1-cm pulmonary nodule with an intact bilayered architecture, including a continuous basal cell layer. However, both luminal and basal cells showed marked high-grade atypia, diffuse strong P53 expression, and an increased Ki-67 index of approximately 10%. Sequencing identified a pathogenic TP53 mutation (p.A161T). The combined findings supported fully malignant carcinoma rather than benign bronchiolar adenoma/ciliated muconodular papillary tumor (BA/CMPT); the lesion was classified as non-small cell lung cancer, not otherwise specified, with a distinctive bilayered phenotype.
What made this case unusual
The lesion retained the basal cell layer usually regarded as a marker of BA/CMPT and benign behavior, yet showed high-grade atypia in both cell compartments and shared P53 expression, supporting malignancy.
Diagnostic / clinical pearl
An intact basal cell layer does not by itself establish benignity. In a bilayered pulmonary lesion, assess cytology alongside immunophenotypic and molecular findings before classifying it as BA/CMPT.
Why it matters
This morphology can mimic BA/CMPT and risk underdiagnosis; integrating cytologic, immunohistochemical, and sequencing findings supported correct classification in this case.