A rare case of non-cystic osteitis fibrosa in a twelve week-old male Wistar rat

A case of non-cystic osteitis fibrosa was observed as a spontaneous lesion in a twelve week-old male Wistar rat from a repeated dose toxicity study. The rat did not show abnormal clinical signs, changes in food consumption and body weight gain throughout the study period. No abnormalities were noticed for haemato-biochemical parameters. The bone marrow cytology of the rat showed no pathological alterations. Histopathological examination of femur showed moderate fibrosis along with mononuclear cell infiltration, increased multinucleated osteoclastic activity and few osteoblasts. Other organs of the rat did not reveal any abnormalities. These findings were suggestive of osteitis fibrosa with no cyst formation.