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What Are Sarcomatoid Neoplasms of the Lung?
Sarcomatoid lung carcinomas include giant cell and spindle cell neoplasm. Their names are derived from the appearance of the tumor cells when viewed microscopically. These rare neoplasms (cancers) account for less than 1% of all invasive lung malignancy. The classification of these carcinomas is often complex and controversial. The World Health Organization uses 'sarcomatoid carcinoma' as a general term covering carcinosarcoma, pleomorphic carcinoma, spindle cell neoplasm, giant cell tumors and blastoma.
Immunohistochemistry and electron microscopy have contributed to a better understanding of these tumors. The exact mechanisms by which these tumors develop is unclear, but molecular data suggests that they develop from stem cells that are capable of differentiation into both carcinomatous and sarcomatous elements.
Diagnosis: Most of these tumors can be classified by light microscopy alone, although immunohistochemistry, such as staining for keratin may also be needed. Examination of small tissue biopsies may not be sufficient and definitive diagnosis often requires surgical specimens. These lung cancers generally occur in older adults, with most patients being in the 60-70 age range. These cancers are far more common in men than in women and are strongly linked to heavy smoking. Patients commonly present with thoracic pain, coughing and hemoptysis (coughing up blood). These tumors tend to present as large masses and often invade the chest wall.
Prognosis for carcinosarcomas of the lung is poor and less than 10% of patients survive for more than two years after diagnosis.
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Subtypes of Sarcomatoid Carcinomas
Pleomorphic carcinomas are aggressive (fast growing) malignancies. Average patient survival from diagnosis ranges from 5-35 months. These tumors often spread to the small bowel.
Blastomas and carcinosarcomas are often treated by surgical resection (removal). If the tumor is advanced, a combination of chemotherapy and radiation therapy may be used to lessen symptoms and make a patient more comfortable, since it is unlikely to be curative.
Giant cell carcinomas consist entirely of anaplastic, 'giant' tumor cells with many nuclei.
Spindle cell neoplasm is defined as a carcinoma consisting only of spindle-shaped tumor cells. It is similar to pleomorphic carcinoma in its microscopic appearance and aggressive clinical characteristics. Spindle cell carcinoma is frequently mixed with benign connective tissue and may also be combined with giant cell carcinoma. In rare cases, there may be inflammatory areas, often leading to misdiagnosis of inflammatory disease, such as necrotizing granulomas. In such cases, evidence of tumor cell invasion into the blood vessels can rule out inflammatory disease and aid a diagnosis of malignancy.
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Sarcomatoid Neoplasms of the Lung and Pleura. W.Travis. Archives of Pathology & Laboratory Medicine, 2010, Vol.134, P1645-1658.
Sarcomatoid carcinoma of the lung: histologic criteria and common lesions in the differential diagnosis. T.Franks & J.Galvin. Archives of Pathology and Laboratory Medicine, 2010, Vol 134, P49-54.