1995 Volume 34 Issue 4 Pages 603-607
We conducted a morphological investigation of the Papanicolaou staining (Pap.) of myoepithelial cells (MEC) in the normal lactiferous duct system and mammary gland benign tumors. For the normal lactiferous duct system, extirpated breast tissue from 5 mammary carcinoma cases was employed, and the MEC was sampled from mammary large ducts and peripheral lactiferous ducts. After Pap. staining photography, decoloring was performed, and the enzyme antibody method was used to stain smooth muscle actin (SMA), and the SMA positive cells and Pap. staining results were compared. The same procedure, with aspiration cytology, was used for the comparison of 31 cases of fibroadenoma and 7 cases of intraductal papilloma, the latter of which had been diagnosed histologically. In the study of the normal lactiferous duct system, the N/C ratio of the MEC of the mammary large duct type was very low, and the cells had abundant cytoplasm readily stained light green in fibrous fashion. The MEC of the peripheral lactiferous ducts on the edges of the epithelial cell clusters or above them appeared as spindle-shaped to oval-type naked nuclear cells with unclear cytoplasm. MEC of the fibroadenoma showed denselystained spindle-to-oval-shaped naked nuclear cells with granular chromatin. In the round nuclei, we observed epithelioid MEC with lace-like cytoplasm stained light green. Localization appeared in the form of cell clusters on the outermost layer and above the cell grouping. In the intraductal papilloma, the MEC resembled the naked nuclear-type originating in peripheral lactiferous ducts, or looked like the MEC with clear cytoplasm having a microfibrillar appearance that stained light green or, in some cases stained darkly and originated in mammary large ducts. Based on the findings of the present investigation, mammary gland MEC, both in the normal lactiferous duct system and benign lesions of the mammary gland, can be divided into two types, mammary large duct and peripheral lactiferous duct types, each with markedly different Pap. staining.
