Frontal Chest X-Ray indicating bronchial Carcinoma. The three yellow arrows in the left upper lobe indicate the adenocarcinoma. An adenocarcinoma is a malignant tumour that develops in the lining or inner surface (epithelial tissue) of an organ and is formed from glandular (secretory) structures. The purple arrow indicates enlarged left hilar lymph nodes. (‘The hilar is a complex anatomical structure that appears as a wedge-shaped depression on the mediastinal surface of each lung where the bronchus, blood vessels, nerves and lymphatics enter or leave the lung’)(1). Findings: Adenocarcinoma: Bronchial carcinoma with lymphadenopathy.
Adenocarcinoma is the most common type of non-small-cell lung cancer accounting for around 40% of all cases. It is commonly found in current or former smokers but paradoxically, it is also the most common type of lung cancer found in people who have never smoked.(2) Adenocarcinomas usually occur in the peripheral (or outer) portion of the lungs.
Non-Small-Cell Lung Cancers
The classification of lung cancers are divided into two main categories:- non-small-cell lung carcinoma (NSLC) and small-cell lung carcinoma (SCL)(3) this distinction is useful for therapeutic purposes as management and treatment tends to be similar for non-small-cell lung cancers and quite different for small-cell cancers. In this post we will be looking at non-small-cell lung carcinomas only. Non-small-cell lung carcinomas (NSCLC) are the most common form and account for around 85 – 90% of total lung cancers.(4) The three main types of non-small-cell lung cancers, are classified according to the types of cells involved, and are adenocarcinoma (see Image 1), squamous cell carcinoma (see Image 2) and large-cell carcinoma (see image 3).
Chest x-ray of a 60 year old male patient. There is a large peripheral mass visible in the left upper lobe next to the oblique fissure, (in the left lung, the oblique fissure separates the superior or upper lobe from the inferior or lower lobe). Further Lateral chest x-ray revealed an irregular opacity with an area of air density lucency that is consistent with an air-fluid level indicating a cavity. Findings: (after follow up CT scan and biopsy results) Squamous Cell Lung Carcinoma
Squamous cell lung carcinoma (also called epidermoid carcinoma) is a cancer that forms in the squamous cells, which are round, flat cells that replace injured or damaged cells in the lining of the lung’s bronchi. Squamous cell tumours usually occur in the central portion of the lung or in one of the main airway branches. If these lesions grow to a large size hollow cavities appear that are associated with cell death and commonly found at the centre of the tumour, as demonstrated in the above case. Squamous-cell carcinoma is primarily caused by smoking(5) and accounts for around 30% of all lung cancers.
Chest x-ray if an adult male showing a large 8cm mass in the left upper lobe (purple arrow). No invasion of the chest wall and no obvious signs of lymph node involvement or metastases.
Large-cell lung carcinoma refers to a diverse group of malignant tumours that originate from the epithelial cells of the lung. Large-cell carcinoma is a name that is given to any tumour that cannot be definitively histologically classified as a small-cell, squamous-cell or adenocarcinoma. Large-cell carcinomas are so named because the cells appear large and rounded under a microscope with excess cytoplasm cytoplasm (all the material in a living cell except the nuclei) and large nuclei. These types of cancer account for around 9 % of all lung carcinomas and tend to be very fast growing.
Other less common types of non-small cell lung cancer are: pleomorphic, carcinoid tumor, salivary gland carcinoma, and all carcinomas that are histologically unidentifiable known as unclassified lung carcinomas.
2. Subramanian, J.; Govindan, R. (2007). “Lung Cancer in Never Smokers: A Review”. Journal of Clinical Oncology 25 (5): 561–70. doi:10.1200/JCO.2006.06.8015. PMID 17290066
3. Kumar, V; Abbas AK; Aster JC (2013). “12”. Robbins Basic Pathology (9th ed.). Elsevier Saunders. p. 505. ISBN 978-1-4377-1781-5
4. American Cancer Society: http://www.cancer.org/cancer/lungcancer-non-smallcell/detailedguide/non-small-cell-lung-cancer-what-is-non-small-cell-lung-cancer.
5. Ruth A. Hannon … [et al] (2010). ‘Porth pathophysiology : concepts of altered health states’ (1st Canadian ed. ed.). Philadelphia, PA: Wolters Kluwer Health/Lippincott Williams & Wilkins. p. 660. ISBN 978-1-60547-781-7.