What would renal cancer look like on ultrasound? is it fast or slow growing?

Solid: Most renal cancers appear more solid than normal kidney tissue but some have cystic areas as well. In general, it is a slow growing cancer but it's better to get surgical treatment sooner for best chance of cure.

Variable: Kidney cancers typically appear solid but distinct from surrounding kidney tissue. Sometimes tumors have cystic (fluid-filled) parts as well which can be well appreciated on ultrasound. Small tumors may be difficult to detect on ultrasound. The rate of growth is not reliably determined by any single study, but is more dependent on the nuclear grade and cell type.