Study of alkaline phosphatase activity and DNA content of pterygium tissue showing its degenerative character

A prospective, non-randomised, interventional case series study was designed among 127 specimens obtained from 100 consecutive patients presenting with primary pterygium attending the outpatient department of a teaching hospital in Kolkata, West Bengal between September 2009 and August 2010. After harvesting the pterygium it was transported in 10% formol saline for staining, fixing and embedding prior to evaluation of tissue alkaline phosphatase level and estimation of DNA content in nucleus of cells in pterygium tissue. The main outcome was to measure alkaline phosphatase activity and DNA content in pterygium tissue and normal bulbar conjunctiva along with histopathological staining and to see if any correlation exists between alkaline phosphatase activity and DNA content of pterygium tissue in different stages of evolution as suggested by histological staining. The elastic proliferation and hyaline degeneration are prominent in well developed pterygium. The alkaline phosphatase activity in all cases of pterygium is maximum and the DNA content of the cells of the pterygium tissue is diminished as compared to normal bulbar conjunctiva. Histopathological changes as evident from epithelial cell changes from cylindrical to flat cells with cyst formation in basal layers, the disappearance of nuclei in the submucosa coupled with increase in hyaline content of the tissue all point towards degenerative changes. Biochemically too there is a decrease in DNA content in the nuclei of the cells in pterygium, histochemically there is an increase in the alkaline phosphatase activity, all these changes point to pterygium being a degenerative tissue.