Small-Cell Lung Carcinoma
Small-cell lung carcinoma (SCLC) is less common. It was formerly referred to as "oat-cell" carcinoma. Most cases arise in the larger airways (primary and secondary bronchi) and grow rapidly, becoming quite large. The small cells contain dense neurosecretory granules (vesicles containing neuroendocrine hormones), which give this tumor an endocrine/paraneoplastic syndrome association.
While initially more sensitive to chemotherapy and radiation, it is often metastatic at presentation, and ultimately carries a worse prognosis. Small-cell lung cancers have long been dichotomously staged into limited and extensive stage disease. This type of lung cancer is strongly associated with smoking.
Others
Lung cancers are highly heterogeneous malignancies, with tumors containing more than one subtype being very common. Currently, the most widely recognized and utilized lung cancer classification system is the 4th revision of the Histological Typing of Lung and Pleural Tumours, published in 2004 as a cooperative effort by the World Health Organization and the International Association for the Study of Lung Cancer.
It recognizes numerous other distinct histopathological entities of non-small-cell lung carcinoma, organized into several additional subtypes, including sarcomatoid carcinoma, salivary gland tumors, carcinoid tumor, and adenosquamous carcinoma. The latter subtype includes tumors containing at least 10% each of adenocarcinoma and squamous cell carcinoma.
When a tumor is found to contain a mixture of both small-cell carcinoma and non-small-cell carcinoma, it is classified as a variant of small-cell carcinoma and called a combined small-cell carcinoma. Combined small-cell carcinoma is the only currently recognized variant of small-cell carcinoma. In infants and children, the most common primary lung cancers are pleuropulmonary blastoma and carcinoid tumor.
Metastasis
The lung is a common place for metastasis of tumors from other parts of the body. Secondary cancers are classified by the site of origin; e.g., breast cancer that has spread to the lung is called breast cancer. Metastases often have a characteristic round appearance on chest radiograph.
Solitary round lung nodules are not infrequently of an uncertain etiology and may prompt a lung biopsy. In children, the majority of lung cancers are secondary. Primary lung cancers themselves most commonly metastasize to the adrenal glands, liver, brain, and bone.
Wikipedia
0 comments
Post a Comment