What exactly is atypical lobular hyperplasia?

ALH. Atypical lobular hyperplasia (alh) is an overgrowth of the cells lining the lobules which are the sacks at the ends of the breast ducts and the cells look different from the normal lobular cells. The finding of atypia (alh or ADH (vasopressin) - atypical ductal hyperplasia) is a risk marker for future breast cancer. Depending on how the alh was found further biopsy may be needed to r/o early cancer changes.
A proliferation. Of the cells in the lobules of the breast. It is a risk factor, but a nonobligatory precursor for the subsequent development of breast cancer. It is usually multicentric and can be bilateral in some women. It is usually not associated with mammographic abnormalities.