Arising centrally in this lung and spreading extensively is a small cell anaplastic (oat cell) carcinoma. The cut surface of this tumor has a soft, lobulated, white to tan appearance. The tumor seen here has caused obstruction of the main bronchus to left lung so that the distal lung is collapsed. Oat cell carcinomas are very aggressive and often metastasize widely before the primary tumor mass in the lung reaches a large size.

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