1. Normal variant = atypical finding that is normally seen in some percentage of the population. Generally has no clinical significance, and is considered within the spectrum of normal findings.
2. Anomaly = abnormality, without reference to whether a finding has clinical relevance.
3. I don't use anomaly in my reports -- feel it is too vague.
4. Fabella = normal variant. Lots of people have one, and it has little to no clinical bearing. These are not routinely reported at my institution, given how normal they are.