Hibernoma : Microscopic Features
Microscopic Features: In a classic hibernoma, greater than 70% of the tumor resembles brown fat. It shows an admixture of: 1) large polygonal, round or ovoid cells with abundant granular eosinophilic cytoplasm, distinct cytoplasmic borders, and round centrally-placed nuclei with prominent nucleoli; 2) multivacuolated large adipocytes with central nuclei; and 3) variable numbers of mature univacuolated adipocytes (white fat). All three cell types are seen in this image. There is no cytologic atypia and mitotic activity is not increased.