Erosive adenomatosis of the nipple (also called florid papillomatosis of the nipple ducts) is an uncommon disease since only 358 cases have been published. We observed 10 cases in 10 years, corresponding to 1 case in 8,500 skin biopsies. One of these cases concerned a male patient and is the 13th of this kind in the literature. In our series the mean duration of symptoms was 15 months, as against 25 months in the 121 published cases where duration was clearly specified. In 8 of our 10 cases the patients consulted for oozing erosion or discharge of the nipple. Physical examination showed a palpable nodule in 2 cases, a small pediculate tumour in 1 case and nipple enlargement in 50 p. 100 of the cases. The patients were followed up for as much as 7 years. The outcome was always favourable. Recurrence was observed in only one patient, 7 months after limited excision; 6 years after a second excision no relapse was noted. Histological examination showed a papillomatous lesion in 5 cases, an adenomatous lesion in 2 cases and a mixed lesion in 3 cases. Myoepithelial cells were found in all cases, but they were doubtful or discreet in 4 cases. The apical pole of columnar cells was labelled by the ACE antibody, but labelling was very weak and partial in 4 cases. The columnar cell cytoplasm was constantly and strongly labelled by the KL1 anti-keratin antibody. The apical pole of parietal cells was strongly labelled by the antiepithelial membrane antigen antibody (EMA) in all cases.(ABSTRACT TRUNCATED AT 250 WORDS)