Tumor Causes 

A neoplasm could be caused an abnormal proliferation of tissues, which could be caused by genetic mutations. Not all types of neoplasms cause a tumorous overgrowth of tissue, however .

Benign conditions that are not associated with an abnormal proliferation of tissue could also present as tumors, however, but have no malignant potential. Breasts cysts are another example, as are other encapsulated glandular swellings .

Encapsulated hematomas, encapsulated necrotic tissue , & keloids & granulomas might also present as tumors.

Discrete localized enlargements of normal structures due to outflow obstructions or narrowings, or abnormal connections, might also present as a tumor. Examples are arteriovenous fistulae or aneurysms , biliary fistulae or aneurysms, sclerosing cholangitis, cysticercosis or hydatid cysts, intestinal duplications, & pulmonary inclusions as seen with cystic fibrosis. It could be dangerous to biopsy a number of types of tumor in which the leakage of their contents would potentially be catastrophic. When such types of tumors are encountered, diagnostic modalities such as ultrasound, CT scans, MRI, angiograms, & nuclear medicine scans are employed prior to biopsy and/or surgical exploration/excision in an attempt to avoid to avoid such complications.

The nature of a tumor is determined by imaging, by surgical exploration, and/or by a pathologist after examination of the tissue from a biopsy or a surgical specimen.