Human breast adenosis, light micrograph. Adenosis is a benign (non-cancerous) change consisting of an enlargement of the lobules with an increased number of ductules, or acini, within them. Here lobules are occupied by the tubular duct lobular unit (TDLU), with a hyperplasia of terminal ducts, which is characteristic of adenosis. Intralobular stroma is rich in collagen fibres (fibrosis).