Small cell carcinoma
| Small-cell carcinoma | |
|---|---|
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| Micrograph of a small-cell carcinoma of the lung showing cells with nuclear moulding, minimal amount of cytoplasm and stippled chromatin. FNA specimen. Field stain. | |
| Classification and external resources | |
| ICD-O | M8041/3 |
| MedlinePlus | 000122 |
| eMedicine | med/1336 |
| MeSH | D018288 |
Small-cell carcinoma (also known as "small-cell lung cancer", or "oat-cell carcinoma") is a type of highly malignant cancer that most commonly arises within the lung, although it can occasionally arise in other body sites, such as the cervix,prostate, and gastrointestinal tract. Compared to non-small cell carcinoma, small cell carcinoma has a shorter doubling time, higher growth fraction, and earlier development of metastases.
Small-cell carcinoma of the lung usually presents in the central airways and infiltrates the submucosa leading to narrowing of bronchial airways. Common symptoms include cough, dyspnea, weight loss, and debility. Over 70% of patients with small-cell carcinoma present with metastatic disease; common sites include liver, adrenals, bone, and brain.
Small-cell carcinoma is an undifferentiated neoplasm composed of primitive-appearing cells.
As the name implies, the cells in small-cell carcinomas are smaller than normal cells, and barely have room for any cytoplasm. Some researchers identify this as a failure in the mechanism that controls the size of the cells.
Due to its high grade neuroendocrine nature, small-cell carcinomas can produce ectopic hormones, including adrenocorticotropic hormone (ACTH) and anti-diuretic hormone (ADH). Ectopic production of large amounts of ADH leads to syndrome of inappropriate antidiuretic hormone hypersecretion (SIADH).
Lambert-Eaton myasthenic syndrome (LEMS) is a well-known paraneoplastic condition linked to small-cell carcinoma.
When associated with the lung, it is sometimes called "oat cell carcinoma" due to the flat cell shape and scanty cytoplasm.
It is thought to originate from neuroendocrine cells (APUD cells) in the bronchus called Feyrter cells (named for Friedrich Feyrter). Hence, they express a variety of neuroendocrine markers, and may lead to ectopic production of hormones like ADH and ACTH that may result in paraneoplastic syndromes and Cushing's syndrome. Approximately half of all individuals diagnosed with Lambert-Eaton myasthenic syndrome (LEMS) will eventually be found to have a small-cell carcinoma of the lung.
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