Welcome to Health care magic.
1.Lump in the axillary region - probable cause is
lymph nodal enlargement.
2.Lymph nodal enlargement is seen in presence of local / systemic inflammation and infection, presence of malignancy / cancer.
3.Your doctor has examined the breast and did not find any lump - but probably he want to rule out the possible pathologies / cancer / malignancy with out lump/mass.
4.Like tiny micro calcifications are not palpated and not seen on the
ultrasound - only seen on
mammogram ( probably doctor want to rule out).
5.An ultrasound is done in correlation with the mammogram, small lesions which are hard to assess on mammogram can be identified on the ultrasound ( ducts dilatation, inflammatory changes ).
Only after imaging one can come to conclude, definitive will be FNAC - fine needle aspiration cytology /
BIOPSY.
Hope it helps you. Wish you a good health.
Anything to ask ? do not hesitate. Thank you.