heterogeneous
Meaning of heterogeneous: One word doing three jobs, in radiology, pathology and research, and the reason a single sample can misrepresent a whole tumor.
Definition of heterogeneous
Heterogeneous means made up of parts that are not alike. In medicine it describes tissue whose appearance varies from place to place on a scan, a tumor whose cells differ from one another, or a group of patients or diseases sharing a label without sharing a cause. Its opposite is homogeneous, meaning uniform throughout.
Where does the word appear?
| Setting | What it describes |
|---|---|
| Imaging report | Tissue with a mottled or uneven appearance |
| Pathology report | Cells within one tumor that differ in appearance or genetics |
| Research paper | Studies or participants too different to pool sensibly |
| Genetics | One clinical picture produced by faults in several genes |
The word is neutral. A heterogeneous appearance on a scan is not automatically abnormal, since many normal tissues are uneven, and the radiologist is usually noting that a finding cannot be described in one word rather than raising an alarm.
Why does heterogeneity within a tumor matter?
Because a biopsy samples one place. If cells at one edge of a tumor carry a genetic change that cells at the other edge lack, a treatment aimed at that change clears part of the tumor and leaves the rest, and the surviving population then regrows. This is among the main reasons a treatment that works at first stops working later. Methods such as fluorescence in situ hybridization can show that neighboring cells in a single sample differ, which is how the phenomenon was first demonstrated directly.
What does it mean applied to a disease?
That the name describes a pattern rather than a mechanism. Several hereditary conditions look identical in the clinic while arising from faults in entirely different genes, and calling such a group heterogeneous is a way of saying that one label covers several diseases. The same caution applies to research: pooling results from studies heterogeneous in design or population produces an average that may describe nobody.
Also known as
Used in a sentence
The mass had a heterogeneous appearance with central areas of necrosis.
Good to know
Applied to a tumor the word carries a practical warning, since a biopsy samples one region and a result from that region may not represent cells elsewhere in the same mass.
Word origin
Where “heterogeneous” comes from
From the Greek heteros, meaning other or different, with genos, meaning kind or type, so the word means of differing kinds.