Fibroepithelial hyperplasia in an entire male cat: cytologic and histopathological features.

Fibroepithelial hyperplasia (FEH) of the mammary glands in cats (also known as fibroadenomatosis or feline mammary hyperplasia) was first described in 1973 (1). The syndrome involves the usually reversible, rapid, non-neoplastic enlargement of one or more mammary complexes (4) and is not uncommon in female cats. There is no milk production. Around 20% of all feline mammary masses are non-neoplastic in origin and most of these are FEH (7). The majority of affected cats are young (under 2 years of age), intact females (22). In this group, FEH can occur spontaneously before the first oestrus (7), some weeks after oestrus, or during pregnancy or pseudopregnancy (8, 9). The syndrome can also oc cur subsequent to treatment with progesterone or synthetic gestagens (13). There are few reports in the literature of FEH in male cats, in the majority of these cases FEH occurred after gestagen treatment.