The diagnosis of neoplasia can be simple
when a solid mass can be visualised or palpated, or when it can be identified on
radiographic or ultrasound examination. But care is needed when considering the visual
appearance of a tumour alone because appearances can be deceptive! An innocuous looking
tumour of the skin could be a mast cell tumour, or a small black growth in the mouth
could be a malignant melanoma, and fibrosarcomas along the gum margin of dogs often
look benign (even under microscopic examination they can be misdiagnosed as fibromas)
but they are in fact extremely invasive.
In all cases the diagnosis should be confirmed by the histopathological examination
of a biopsy, or occasionally by the examination of fine needle aspirates or other
techniques for obtaining neoplastic cells, e.g. impression smears.
In many cases the clinical signs associated with a neoplasm are non-specific and
are due to systemic side-effects called paraneoplastic signs (Table 6.8). In geriatric
patients it is important to evaluate the significance of such signs to rule out the
possibility of the presence of a malignant or benign neoplasm.