Immunohistochemical staining of lipid droplets with adipophilin in paraffin-embedded glioma tissue identifies an association between lipid droplets and tumour grade

Background: Cytoplasmic lipid droplets are important in cancer metabolism and a clear relationship has been established between their accumulation and increased tumour grade in glioma. The development of the novel immunohistochemical marker adipophilin has proven to be a useful method of detecting lipid droplets in paraffin embedded tissue from many diseases. Our aim was to assess the distribution of adipophilin stained lipid droplets in paraffin embedded glioma tissue and to evaluate whether it is a useful indicator of lipid droplets in brain tumours. Methods: Immunohistochemical staining for adipophilin was undertaken in a tissue microarray containing 65 paraffin embedded gliomas of varying grade. The number of tumour cells containing adipophilin positive lipid droplets was then quantified and statistically analysed. Results: We found a statistically significant accumulation of lipid droplets in high grade glioblastoma compared to low grade astrocytomas when we quantified the percentage of tumour cells containing adipophilin-positive lipid droplets (p<0.001). A significant positive correlation (rs=0.83) was detected between increasing tumour grade and the percentage of tumour cells containing lipid droplets, p=0.0001. Conclusions: We have determined that adipophilin is a useful immunohistochemical marker of lipid droplets in brain tumours. The ability to detect lipid droplets within paraffin embedded gliomas will greatly facilitate the evaluation of this tumour characteristic which is related to grade and prognosis.