All of the following are malignant tumours EXCEPT:

Papilloma is categorized as a benign tumor, which means it does not possess the characteristics typically associated with malignancy, such as invasive growth or the ability to metastasize to other tissues. It arises from epithelial tissue and generally remains localized without spreading to surrounding structures.

In contrast, astrocytomas, fibrosarcomas, and melanomas are all classified as malignant tumors. Astrocytomas originate from astrocytes in the brain and can invade surrounding brain tissue. Fibrosarcomas are malignant tumors that arise from fibrous connective tissue and have the potential to metastasize. Melanomas, which develop from melanocytes (pigment-producing cells), are known for their aggressive nature and ability to spread to other parts of the body.

Thus, the distinction of papilloma as a benign tumor solidifies it as the only non-malignant option among the list provided. Understanding these classifications is essential in health information management as it aids in accurate documentation and treatment planning.