Oestrogen and progesterone receptors in feline fibroadenomatous change: An immunohistochemical study

The distribution of oestrogen and progesterone receptors was analysed in 18 cases of feline fibroadenomatous change (FFAC) using commercially available specific monoclonal antibodies and the Avidin-biotin peroxidase complex technique on formalin-fixed, paraffin-embedded tissue. In all cases of FFAC, progesterone receptors were detected either in epithelial cells (mostly suprabasal) or in epithelial and stromal cells. Oestrogen receptors were detected in approximately half of these cases, in suprabasal or luminal epithelial cells exclusively. Myoepithelial cells lacked both oestrogen and progesterone receptors. The techniques used have identified the specific cellular distribution of steroid hormones receptors in this hormone-dependent lesion of the feline mammary gland. The results confirm those of previous biochemical analyses with respect to progesterone receptors and add new data concerning the possible involvement of oestrogen receptors and stromal fibroblasts in the hormonal control and development of the lesion.