Please answer: what means ill marginated focal asymmetry of low density in mammogram? should i be worry?

See your doctor: Mammograms are used to determine who needs further evaluation and closer monitoring. You should follow up with your doctor to discuss further plans prior to worrying. The worrisome finding usually seen on mammograms is calcification in a mass that can be felt or microcalcifications in the breast with no mass present.

Probably not.: A focal asymmetry is one that is seen in 2 views on a mammogram (the top down view and the side to side). "low density" means if is more likely to be benign (not malignant). But it must be further evaluated with additional mammographic views, ultrasound and rarely MRI may be required. A six month follow up mammogram may be recommended if the work up determines that it is 97% likely to be benign.

Asymmetry: Can't tell at this point. An asymmetry is not a mass, by definition it doesn't have well defined margins(or else it would be a mass). It sounds like it needs further evaluation: additional mammographic views, and possibly ultrasound. If these studies do not clear things up, it may need a needle biopsy for a definitive diagnosis.These usually turn out benign, but not always, so please see your doc