Like other forms of lung cancer, Bas-SqCC is ultimately diagnosed after a pathologist examines a tumor sample containing viable malignant cells and tissue under a light microscope and identifies certain particular characteristics. In the case of Bas-SqCC, it is essential that both evidence of<unk>  differentiation (i.e., intercellular bridges, production of keratin, tonofilament bundles) and basaloid architecture (i.e. prominent peripheral palisading of cell nuclei, organoid/lobular structures) are identified to make a correct diagnosis. Immunohistochemical markers that have been suggested to be useful in making an accurate diagnosis of Bas-SqCC include positivity for p63 and high molecular weight keratin (i.e. 34betaE12), and lack of expression of thyroid transcription factor-1 (TTF-1). Among other pulmonary malignancies, the main differential diagnoses in suspected cases of Bas-SqCC include the high-grade neuroendocrine carcinomas, such as small cell carcinoma and large cell neuroendocrine carcinoma. The issue of differential diagnosis is particularly acute when the pathologist must use a small biopsy specimen or cytology. In addition, the basaloid variant of SqCC can be difficult to distinguish from other poorly differentiated<unk>  cell carcinomas.
Basaloid squamous cell lung carcinoma
Salivary gland–like carcinoma of the lung
Adenosquamous lung carcinoma
Epithelial-myoepithelial carcinoma of the lung
Sarcomatoid carcinoma of the lung
Basaloid large cell carcinoma of the lung
Mucinous cystadenocarcinoma of the lung
Giant-cell carcinoma of the lung