What Causes Milky Discharge After Mammary Glands Removal?

my sister is 59 yr old. she had a hysterectomy (total) at age 28. she had her mammary glands removed (bilateral) 6 yrs ago. several times since she has had a milky discharge from her breasts, that she can express manually. she saw her pcp and was dx'd as "lactating" symptoms. she was to not touch her breasts for 2 months. ????