SUMMARY
The purpose was to determine and classify the histological changes that occur on primary acquired nasolacrimal duct obstruction. It was made a prospective study of 51 specimens biopsed during external dacryocystorrinostomy in 50 cases of primary acquired nasolacrimal duct obstruction. The ducts were classified on three histopathological patterns: inflammatory in chronification (9.8%), inflammatory chronic without fibrous obliteration (58.8%) and inflammatory chronic with fibrous obliteration (31.4%>).
There was a positive association between the third pattern and the absence of luminal epithelium.
The three histopathological patterns didn't show difference when compared in relation to the evolution period of the symptoms.