General features of usual ductal hyperplasia of the breast:
(1) thickening of the epithelial layer
(2) absence of atypical or malignant features
(3) nucleoli are absent or inconspicuous (exception: apocrine metaplasia)
(4) nuclear chromatin is uniform and nuclear membranes are thin
(5) nuclear size normal or only slightly increased
(6) nuclear spacing is uneven with variable crowding
(7) mitoses are rare and regular
(8) cytoplasmic borders are inconspicuous
(9) necrosis may be present but should lack a histiocytic response and microcalifications
Parameters used for grading:
(1) thickness of the epithelium
(2) histologic patterns
(3) duct size
(4) other findings
Mild ductal hyperplasia shows:
(1) epithelial layer: 3 to 4 cells thick (excluding myoepithelial layer)
(2) patterns: flat, papillary
(3) duct size: normal
Moderate hyperplasia shows:
(1) epithelial layer: >= 5 cells thick (excluding myoepithelial layer)
(2) patterns: flat, papillary, micropapillary, bridging, streaming, squamous metaplasia, fenestrated, aporcrine metaplasia
(3) duct size: normal or slightly increased
(4) microcalcifications may be present
Severe/florid hyperplasia shows features of moderate hyperplasia plus:
(1) lumina almost or completely filled with epithelial cells
(2) duct size: increased
(3) tends to involve a gaggle of ducts
Fibrocystic mastopathy with mild hyperplasia is termed non-proliferative.
Fibrocystic mastopathy with moderate and florid hyperplasia is termed proliferative.
